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U.S. Army Corps of Engineers South Pacific Division Los Angeles District SANTA CRUZ R IVER W ATERSHED MANAGEMENT STUDY P IMA COUNTY, ARIZONA Appendix C1 Historic Flood Damages August 2001

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Page 1: SANTA CRUZ RIVER WATERSHED MANAGEMENT STUDYwebcms.pima.gov/UserFiles/Servers/Server_6/File... · Santa Cruz River Watershed Management Study Final Feasibility Report and Appendices

U.S. Army Corps of Engineers South Pacific Division Los Angeles District

SANTA CRUZ RIVER WATERSHED MANAGEMENT STUDY

PIMA COUNTY, ARIZONA

Appendix C1 Historic Flood Damages

August 2001

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U.S. Army Corps of Engineers South Pacific Division Los Angeles District

SANTA CRUZ RIVER WATERSHED

MANAGEMENT STUDY

PIMA COUNTY, ARIZONA

Appendix C2 Economic Assessment

August 2001

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Appendix C2- Economic Assessment Page C2-1 August 2001

TABLE OF CONTENTS

INTRODUCTION ........................................................................................................................3 STUDY AUTHORITY..................................................................................................................3 ECONOMIC ASSESSMENT STUDY AREA ...............................................................................4 DAMAGE CATEGORIES............................................................................................................4

Inundation Damages...............................................................................................................4 Infrastructure Damages ..........................................................................................................4 Erosion Damage .....................................................................................................................5 Emergency Costs ...................................................................................................................5

DAMAGE ASSESSMENT METHODOLOGY..............................................................................5 Data Collection .......................................................................................................................5 Structural/Content Inundation Damage Methodology..............................................................6 Agricultural Damage Methodology ..........................................................................................8

Cotton Production Damage .................................................................................................8 Agricultural Irrigation and Production Land Damage............................................................9

Emergency Costs .................................................................................................................11 FEMA – Temporary Rental Assistance/Funds for Minor Emergency Home Repairs..........11 FEMA – Public Assistance Program..................................................................................11 Clean-up Costs .................................................................................................................13 Erosion Damage ...............................................................................................................14

REACH 1 DAMAGES ...............................................................................................................14 REACH 2 DAMAGES ...............................................................................................................14

Agricultural Damages............................................................................................................15 Public Infrastructure Damage................................................................................................15 Railroad Damage..................................................................................................................15 Reach 2 Damage Summary..................................................................................................16

REACH 3 DAMAGES ...............................................................................................................16 REACH 4 DAMAGES ...............................................................................................................16 REACH 5 DAMAGES ...............................................................................................................17 REACH 6 DAMAGES ...............................................................................................................18

Agricultural Damages............................................................................................................18 Public Infrastructure Damage................................................................................................18 Structural and Content Inundation Damage ..........................................................................19 Clean-up Costs .....................................................................................................................20 Emergency Costs .................................................................................................................20 Reach 6 Damage Summary..................................................................................................20

SANTA CRUZ RIVER WATERSHED FLOOD DAMAGE SUMMARY .......................................21

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Appendix C2- Economic Assessment Page C2-2 August 2001

LIST OF TABLES Table 1 - FEMA Damage Percentages .......................................................................................6 Table 2 - Reach 6 Water Surface Profiles...................................................................................8 Table 3 - Cotton Farm Budget...................................................................................................10 Table 4 - FEMA Disaster Relief.................................................................................................12 Table 5 - TRA - Average Per Claim Expenditure.......................................................................12 Table 6 - Public Assistance to TRA Expenditures .....................................................................13 Table 7 - Reach 1 Agricultural Damages...................................................................................14 Table 8 - Reach 2 Agricultural Damages...................................................................................15 Table 9 - Reach 2 Public Infrastructure Damage.......................................................................15 Table 10 - Reach 2 Damage Summary.....................................................................................16 Table 11 - University of Arizona Study’s Erosion Inventory .......................................................17 Table 12 - Reach 4 Eroison Damages ......................................................................................17 Table 13 - Reach 6 Agricultural Damages.................................................................................18 Table 14 - Reach Public Infrastructure Damage........................................................................19 Table 15 - Reach 6 Structure Inventory ....................................................................................19 Table 16 – Reach 6 Inundation Damages.................................................................................19 Table 17 - Reach 6 Clean-up Costs..........................................................................................20 Table 18 - Reach 6 Emergency Costs ......................................................................................20 Table 19 - Reach 6 Damage Summary.....................................................................................20 Table 20 – Watershed Summary - Damages by Reach ............................................................21 Table 21 – Watershed Summary - Categorical Damages .........................................................21

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Appendix C2- Economic Assessment Page C2-3 August 2001

INTRODUCTION

Flood inundation and streambank erosion are significant hazards to property adjacent to the Santa Cruz River in Pima County, Arizona. Numerous past floods have caused severe damage to agricultural crops, private property, and public infrastructure. Streambank erosion, although controlled in many places, continues be a threat to private and public facilities. This erosion threat is readily apparent in the vicinity of the University of Arizona’s West Campus Agricultural Center [WCAC] (Reach 4 of the study area) where erosion not only threatens this renowned agricultural genetic and research center but also is a danger to Interstate 10. The following economic assessment examines the potential economic damages from a 100-year flood event, as designated by the Federal Emergency Management Agency’s (FEMA) floodplain mapping, along the Santa Cruz River. Further, the assessment examines the damage associated with continued streambank erosion in the vicinity of the West Campus Agricultural Center. This economic assessment diverges from traditional USACE economic studies, in that the examination of a single event precludes the traditional estimation of expected annual damages of USACE economic analyses and only a general overall potential damage is presented. Traditional USACE economic studies examine multiple flood events to arrive at expected annual damages. With the exception of Reach 4, this assessment evaluates only a single event, the 100-year flood, and thus only reflects the potential damages from that event. However, the evaluation of damages for this assessment is constructed to be consistent with the methodologies and in general compliance with ER 1105-2-100 given its restriction of a single event evaluation.

STUDY AUTHORITY

This economic assessment has been conducted under two separate authorities provided by Congress. The first and most recent authority is provided by House Resolution 2425 (HR 2425), dated May 17, 1994. HR 2425 states:

"... the Secretary of the Army is requested to review reports of the Chief of Engineers on the State of Arizona...in the interest of flood damage reduction, environmental protection and restoration and related purposes."

The second authority is given in Public Law 761, Seventy-fifth Congress, and known as Section 6 of the Flood Control Act of 1938. This authority, dated June 28, 1938, states:

“… the Secretary of War (now Secretary of the Army) is hereby authorized and directed to cause preliminary examinations and surveys … at the following localities: … Gila River and tributaries, Arizona …”

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Appendix C2- Economic Assessment Page C2-4 August 2001

ECONOMIC ASSESSMENT STUDY AREA

The economic assessment study area is the FEMA 100-year floodplain along the Santa Cruz River throughout Pima County, as shown in Figure 1A in the main report. This area has been divided into six (6) reaches corresponding to those of the main report and is shown in Figures 11B through 11C. As the figures indicate, significant urbanization of the floodplain occurs principally in Reach 4 and in the southern portion of Reach 5. Residential development is located in the northern portion of Reach 1 continuing into the southern area of Reach 2; however, this development is outside of the FEMA floodplain. Agricultural production is present in Reaches 1, 2, 5, and 6, with rural residential development being present within the floodplain in Reach 6.

DAMAGE CATEGORIES

The damage categories and potential National Economic Development (NED) benefit categories associated with the control of floodwaters within the Santa Cruz River Watershed are inundation damages to structures, contents, and agricultural crops; the prevention of infrastructure losses to agricultural enterprises and public facilities; erosion damages to lands and structures; and public and private cleanup and emergency costs. Overviews of each of these damage categories and potential NED benefit categories are presented below.

Inundation Damages

Inundation damage to residential, commercial, and public structures is measured by taking the existing structural stock and contents and applying the estimated 100-year water surface profile, at the structure’s location. This information is then used in conjunction with FEMA depth-damage functions to derive inundation damages to structures and their contents. Agricultural crop inundation damages and their associated NED agricultural damage reduction benefits are measured by the change in net income, as measured by farm budget analysis. These income changes may result from decreased crop yields and increased production costs.

Infrastructure Damages

Floodwaters can have devastating impacts on public facilities such as roads and bridges. In the Santa Cruz River Watershed study area, numerous bridges have been identified as having a high likelihood of failure under the 100-year flood event. The cost to replace these structures can represent a significant budgetary impact to local governments, especially if this cost can be avoided. In addition to the vehicular bridges identified, several railroad bridges have also been identified as candidates for failure under the 100-year flood event. Besides the cost to replace these railroad bridges, there exists an additional cost of rerouting commerce. Without the

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Appendix C2- Economic Assessment Page C2-5 August 2001

mainline Tucson to Nogales railroad route, traffic would have to be diverted approximately 500 miles through Mexico to continue operations. Agricultural damages would not be limited to crops from a 100-year flood event. Irrigation systems and the land itself would suffer considerable damage. The concrete irrigation channels would fracture and be destroyed under the forces of the 100-year event. Land scour and sediment deposition would drastically alter the laser leveled agricultural lands of the watershed.

Erosion Damage

Erosion, although not tied to a single event, is a serious problem not only for the destruction it can do to structures and land, but for the potential damage it could cause to current and future agricultural and genetic research at WCAC. The loss of current agricultural and genetic research crops could represent the loss of years of experimentation and data. Continued erosion at the WCAC could result in a permanent halt to agricultural and genetic research at this highly respected center, especially if new lands are not available.

Emergency Costs

Emergency costs include those expenses resulting from a flood that would not otherwise be incurred, such as the costs of evacuation and reoccupation, flood fighting, cleanup including hazardous and toxic waste cleanup, and disaster relief; increased costs of normal operations during the flood; and increased costs of police, fire, or military patrol.

DAMAGE ASSESSMENT METHODOLOGY

The collection of data and assessment of damages for this study have been designed to conform to the standards and principals set forth in ER 1105-2-100.

Data Collection

Existing development within the study area was estimated through The First American Corporation’s FASTWeb online data services. This service provides access to county assessor parcel records and includes a variety of data such as parcel number, ownership, size of parcel, land use, type and value of improvements, structure age, and structure size, as examples. A field survey of structures was conducted to determine average first floor elevation of improvements and confirm structure sizes and types for a sample of the existing structures. Agricultural crop acreage by reach was computed using the Pima County Department of Transportation Technical Services - GIS Database Services. Farm budget analysis data for upland cotton was acquired from the online data services of the Arizona Cooperative Extension,

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Appendix C2- Economic Assessment Page C2-6 August 2001

Department of Agricultural and Resource Economics, University of Arizona for 1998, the latest data available. Construction costs for non-railroad bridges were obtained the Pima County Flood Control District – Capital Improvements Projects online database. This database provides the construction year and cost of these improvements. Union Pacific Railroad’s Engineering Department provided current replacement costs for the two railroad bridges subject to damage located in Reach 1 of the study area.

Structural/Content Inundation Damage Methodology

Structural unit counts were obtained as described above using FASTWeb. First floor living area from the FASTWeb service was incorporated and cross-checked through spot field observations. Average structure base elevation was determined through a field survey. Depreciated replacement structure value was estimated using Marshall & Swift valuation service and is at an October 1999 price level. Content to structure value was set at 55% for residential and 75% for agribusiness, based upon ratios developed for prior Los Angeles District studies. FEMA 1998 depth-damage functions were employed for the calculation of inundation damages to structures and contents, as shown below in Table 1.

Table 1 - FEMA Damage Percentages

FEMA – Flood Insurance Rate Review – 1998 Structure Damage Content Damage Depth Consolidated Mobile Home Residential Mobile Home Commercial

-1 0 0 0 0 0 0 17.40 10.04 12.15 3.38 10.46 1 16.33 43.97 24.05 26.65 17.59 2 24.69 62.77 32.73 49.13 23.71 3 27.72 72.72 34.74 64.05 29.51 4 29.64 77.93 36.99 70.33 35.28

Water surface profiles were derived from the continuous hydrology model as developed by Pima County and as described in the Hydrology, Hydraulics and Sedimentation Appendix. Figure 1 shows the water surface cross-sections for Reach 6 and the water surface profile for the 100-year flood at each cross section is shown in Table 2. Reach 6 is the only reach within the current study effort that showed significant development within the floodplain to warrant analysis.

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Appendix C2- Economic Assessment Page C2-7 August 2001

Figure 1 - Reach 6 Cross Sections

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Appendix C2- Economic Assessment Page C2-8 August 2001

Table 2 - Reach 6 Water Surface Profiles

Left Overbank Right Overbank

River Sta

Q100 (cfs)

Water Surface Elevation

(ft)

Elevation (ft)

Depth (ft)

Velocity (ft/s)

Elevation (ft)

Depth (ft)

Velocity (ft/s)

0.00 70000 1861.5 na na 8.25 1862.0 na na 1.61 70000 1883.2 na na 1.47 1880.0 3.2 0.96

2.56 70000 1892.1 1888.0 4.1 2.36 1890.0 2.1 2.08

3.31 70000 1899.4 1895.5 3.9 2.07 1895.5 3.9 1.90

3.88 70000 1905.3 1901.5 3.8 2.76 1903.0 2.3 1.64

4.55 70000 1911.3 1909.0 2.9 1.99 1909.0 2.3 1.58

5.49 70000 1925.1 1920.0 5.1 1.81 1922.0 3.1 1.63

6.25 70000 1936.6 1934.0 2.6 1.19 1935.0 1.6 0.84

7.10 70000 1947.3 1946.0 1.3 1.84 1946.0 1.3 2.01

7.86 70000 1959.0 1953.0 6.0 1.61 1959.0 0.0 1.37

8.81 70000 1970.0 1971.5 na 2.04 1969.0 1.0 1.52

Agricultural Damage Methodology

Cotton Production Damage

Agricultural crop damages are based on the farm budget analysis methodology. For this methodology a late summer, pre-harvest, flood event is assumed. The agricultural damage analysis assumes that cotton is grown on all acres in agricultural production in the study area. This assumption will introduce some error to the assessment; however, this error should be minimal given that over 70% of the crop acreage reported in the U.S. Department of Agriculture’s 1997 Census of Agriculture is in cotton production. The farm budget for cotton based on the data of the Arizona Cooperative Extension is shown in Table 3. The three-year average production yield for Pima County cotton production is:

Lint: 1,009 pounds

Cottonseed: 0.88 tons The FY 2000 Normalized Prices for Arizona cotton lint and cottonseed are $0.675/lb. for lint and $135.08/ton for cottonseed. Total revenue per acre of cotton production is $799.95. Per acre net income for cotton production is $108.33. Assuming a late summer/early fall storm, similar to the storm of 1983, destruction of the cotton crop would occur just prior to harvesting. Direct production investment (DPI) in the cotton crop equals all production expenses, except for harvest and post harvest, overhead, and

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Appendix C2- Economic Assessment Page C2-9 August 2001

management expenses. The potential per acre DPI loss would equal $507.27. Total per acre loss would equal $615.60, net income plus DPI loss.

Agricultural Irrigation and Production Land Damage

Previous Corps studies on the Santa Cruz River in Pinal County serve as a useful source of information and a guide to the impacts that a large magnitude flood may have on agricultural infrastructure. The Feasibility Study on the Lower Santa Cruz River in Pinal County examined the impact that the 1983 flood had on production land. Flood magnitudes of this type contain the energy and force to significantly alter laser leveled production land through erosion and deposition. The study concluded, through the use of ASCS historical records on the 1983 flood, that the effect of floodwater on production land required releveling at a cost of $320 per acre for land flooded in excess of one foot. In that the general practice of agricultural production in the study area employs laser leveling, this damage value is assumed for the analysis of damages to agricultural production land. These previous Corps studies also examined the impacts of large flood events on irrigation systems. These studies through consultation with the ASCS Office, Soil Conservation Service, Cooperative Extension and industry operators concluded that all farm irrigation systems in the coming years would be equipped with high flow turnout systems. The conversion would be the result of the need imposed by increasing water costs, regulations reducing water allotments and the efficiency gains of the high flow turnouts. Employing the analysis of these studies, the general layout of the farmland is 60 percent of the land will be able to irrigate using 1320-ft. runs; while the remainder will utilize 660-ft. runs. Assuming a 15 percent depreciation factor, the capital investment in these layouts per section is: 1320' run system: $204,210 660' run system: $329,445 Using the 60/40 ratio, the weighted average for irrigation systems is $423.84 per production acre. Employing the depth/damage function of the Lower Santa Cruz River Feasibility Study and assuming an average depth of two feet, the damage to irrigation systems is $259.09 per acre.

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Table 3 - Cotton Farm Budget

Item Budgeted/Acre Total/Acre LAND PREPARATION AND GROWING EXPENSES

Paid Labor 62.28

Tractor 40.44 Hand 6.49

Irrigation 15.35

Chemical and Custom Applications 139.50 Fertilizer 33.90

Insecticide 55.58

Herbicide 31.65 Other Chemicals 18.37

Farm Machinery and Vehicles 52.62

Diesel Fuel 17.56

Repairs and Maintenance 35.06 Irrigation Water 105.00

Other Purchased Inputs 15.07

Seed/Transplants 9.07 Other Services and Rentals 6.00

Total Land Preparation and Growing Expenses 374.47 HARVEST AND POST HARVEST EXPENSES

Paid Labor 9.80

Tractor 4.57 Other/Contract 5.23

Chemical and Custom Applications 21.38

Other Chemicals 21.38 Farm Machinery and Vehicles 54.21

Diesel Fuel 5.65

Repairs and Maintenance 48.56

Custom Harvest/Post Harvest 8.47 Cotton Ginning 81.61

Crop Assessment 7.21

Other Materials 1.67

Total Harvest and Post Harvest Expense 184.35

Operating Overhead (Pickup use) 14.82 Total Operating Expenses 573.64

OVERHEAD EXPENSES

Taxes, Housing & Insurance, Machinery 26.20 General & Office Overhead (5% of TOE) 28.68

General Farm Maintenance (3% of TOE) 17.21

Total Overhead Expenses 72.09 MANAGEMENT SERVICES (8% of TOE) 45.89

TOTAL COST 691.62

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Emergency Costs

ER 1105-2-100 states, “Flood damages are classified as physical damages or losses, income losses, and emergency costs”. The ER then defines emergency costs as “those expenses resulting from a flood that would not otherwise be incurred”. The ER further requires that emergency costs should not be estimated by applying an arbitrary percentage to the physical damage estimates. As with all flood damage estimates and especially in the case of emergency costs, the potentials to double count damages are a distinct possibility and must be guarded against.

FEMA – Temporary Rental Assistance/Funds for Minor Emergency Home Repairs

The Federal Emergency Management Agency (FEMA) provides grants to assist individuals and families to find suitable housing when they are displaced in cases of federally declared disasters. This assistance being directly attributable to the disaster and being an expenditure that would not be undertaken except for the disaster falls clearly under the emergency costs guidance of ER 1105-2-100. Therefore, funds expended by FEMA for Temporary Rental Assistance or Funds for Minor Emergency Home Repairs (TRA) in the event of flooding are NED flood damages. Complying with the ER, an Internet database search of FEMA (www.fema.gov) disaster reports for flood and storm damage was performed. Table 4 shows a compilation of FEMA reports related to various floods and storms. Table 5 shows the average per claim expenditure by FEMA for TRA ranged from $583 to $2,034 with an overall average expenditure of $1,537 per claim. The standard deviation of the average per claim expenditures is $411. For analysis purposes it is assumed that TRA per claim expenditure is $1,537.

FEMA – Public Assistance Program

FEMA will reimburse local and state governments and certain nonprofits up to 75 percent of eligible disaster response costs through the public assistance program. It includes all or parts of the following:

• Debris removal • Emergency protective measures • Road systems and bridges • Water control facilities • Public buildings and contents • Public utilities • Parks, recreational and other activities of a governmental nature

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Table 4 - FEMA Disaster Relief

Location Date Temporary Rental

Assistance Unemployment

Assistance Public

Assistance SBA Disaster

Recovery Loans

Grants for Needs Unmet by Other Government or

Voluntary Agencies

Andrew, Iron etc., MO Apr-99 328,233 384,877

Madison County, MO Apr-99 374,000

Kansas Jan-99 3,380,199 1,196,242 11,676,800 2,459,248

Kansas & Missouri Oct-98 3,335,504 1,806,700 1,140,378

Kansas City, MO Oct-98 4,981,549

Linn Co., MO Oct-98 116,762

South, Central and Southeast Texas

Oct-98 28,047,095 427,324 11,406,977 88,443,500 34,842,781

Washington Oct-98 1,600,000

Southeast Texas Sep-98 4,190,165 23,413 5,267,342 5,555,100 2,209,979

Southwest Texas Aug-98 2,156,601 65,817 4,874,795 6,450,000 5,349,805

Wisconsin Aug-98 7,000,173 3,508,400 693,299

St. Louis City & County, MO Jul-98 1,300,000 212,200 440,491

Massachusetts Jun-98 5,400,000 274,500

Oregon Jun-98 215,294 185,000

North Carolina Jan-98 1,213,285 7,187,159 929,900 306,987

North Dakota Apr-97 180,033,700

California 1998 22,000,000 37,000,000

Georgia 1998 3,100,000 29,300,000 23,500,000 1,800,000

Total 81,666,549 516,554 245,964,526 179,916,100 49,627,845

Table 5 - TRA - Average Per Claim Expenditure

Location Date TRA Funds TRA Claims $ per Claim

Andrew, Iron etc., MO Apr-99 328,233 341 963

Kansas Jan-99 3,380,199 2,388 1,415

Kansas & Missouri Oct-98 3,335,504 3,762 887

South, Central and Southeast Texas Oct-98 28,047,095 13,786 2,034

Southeast Texas Sep-98 4,190,165 2,159 1,941

Southwest Texas Aug-98 2,156,601 1,445 1,492

Wisconsin Aug-98 7,000,173 5,221 1,341

St. Louis City & County, MO Jul-98 1,300,000 2,231 583

Massachusetts Jun-98 5,400,000 3,527 1,531

Oregon Jun-98 215,294 132 1,631

North Carolina Jan-98 1,213,285 703 1,726

California 1998 22,000,000 15,000 1,467

Georgia 1998 3,100,000 2,455 1,263

Total 81,666,549 53,150 1,537

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These costs, as well as the 25 percent contribution by local and state governments and the nonprofits, are eligible NED emergency costs under ER 1105-2-100. Again, care must be exercised to make sure double counting does not occur between public assistance expenditures and structural or other damage categories. Table 6 presents FEMA expenditures on Public Assistance (PA) to TRA expenditures. Total Public Assistance expenditures are 3.01 times the expenditures on TRA. On an individual disaster basis, PA expenditures range from zero to an unknown factor based on the FEMA reports, with the highest reported factor of 9.45.

Table 6 - Public Assistance to TRA Expenditures

Location Date Public Assistance TRA TRA Claims PA/TRA

Andrew, Iron etc., MO Apr-99 328,233 341 0.00

Kansas Jan-99 1,196,242 3,380,199 2,388 0.35

Kansas & Missouri Oct-98 3,335,504 3,762 0.00

Kansas City, MO Oct-98 4,981,549 -

Linn Co., MO Oct-98 116,762 -

South, Central and Southeast Texas Oct-98 11,406,977 28,047,095 13,786 0.41

Washington Oct-98 1,600,000 -

Southeast Texas Sep-98 5,267,342 4,190,165 2,159 1.26

Southwest Texas Aug-98 4,874,795 2,156,601 1,445 2.26

Wisconsin Aug-98 7,000,173 5,221 0.00

St. Louis City & County, MO Jul-98 1,300,000 2,231 0.00

Massachusetts Jun-98 5,400,000 3,527 0.00

Oregon Jun-98 215,294 132 0.00

North Carolina Jan-98 7,187,159 1,213,285 703 5.92

North Dakota Apr-97 180,033,700 -

California 1998 22,000,000 15,000 0.00

Georgia 1998 29,300,000 3,100,000 2,455 9.45

Total 245,964,526 81,666,549 3.01

Clean-up Costs

Clean-up cost estimates are based on studies of the South Pacific Division’s Los Angeles District and North Pacific Division’s, Seattle District.1 The cost on a square foot basis for the extraction of floodwaters, dry-out, and decontamination ranges from $1 to $4.75 based on these prior studies. The current analysis assumes a clean-up cost of $3.65 per square foot.

1 City of Huntington Beach, Infrastructure Restoration Study, Special Study Report, On the Water and Drainage System

Infrastructure, Los Angeles District, August 1998. DRAFT Skagit River, Washington, Flood Damage Reduction Study, Seattle District, 1999.

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Erosion Damage

Erosion, as previously discussed, is mainly a concern in the area around WCAC. Erosion damage potential is principally a long-term process, unlike flood damage. The long-term damage process of erosion is beyond the scope of this study, in that the analysis is related to a single major flood event. However, a recent analysis for the University of Arizona on the erosion problem at WCAC is useful in the identification of the potential erosion problem. This study is reprinted in Appendix A. It should be noted that this study was conducted prior to the current analysis of the frequency/discharge relationship on the Santa Cruz River; and that the relationship employed in the University’s study varies from the current relationship when conclusions drawn from this study are presented.

REACH 1 DAMAGES

Aerial photographic examination of Reach 1 indicates that the only damage category of significant relevance is agriculture. Applying the methodology used for previous reaches on the 620 agricultural acres of Reach 1, yields the following damages.

Table 7 - Reach 1 Agricultural Damages

Cotton Crop Damage $381,669 Irrigation System Damage $160,638 Laser Leveling Costs $198,400

Total Agricultural Damages $740,707

REACH 2 DAMAGES

Reach 2 stretches from approximately the Pima Mine Road Bridge in the north to Continental Road in the south. In this reach two small enclaves of structures, the first at Sahuarita Road east of the river and the second at Duval Mine Road, are located within the FEMA 100-year flood plain. These enclaves were not assessed for economic damages because of their size, approximately 10 to 20 structures each, and the corresponding potential for damages. Agricultural lands comprise much of the acreage of the flood plain. In addition to the agricultural land, several vehicle and railroad bridges cross the river and are subject to erosion and inundation damage. The sections below detail the assessments made for agriculture and the various bridges.

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Agricultural Damages

Reach 2 agricultural lands are estimated at 3,945 acres based on the aerial photographic information (see Figure 11C in the Main Report). Applying the agricultural damage factors defined previously,

Cotton Crop Damage $615.60 Irrigation System Damage $259.09 Laser Leveling Costs $320.00

agricultural damages in Reach 2 for the FEMA 100-year flood are:

Table 8 - Reach 2 Agricultural Damages

Cotton Crop Damage $2,428,524 Irrigation System Damage $1,022,123 Laser Leveling Costs $1,262,400

Total Agricultural Damages $4,713,047

Public Infrastructure Damage

In Reach 2 three vehicular bridges have been identified as likely candidates for failure in the FEMA 100-year flood. These bridges are Pima Mine Road, Sahuarita Road, and Duval Mine Road. Erosion and inundation are the principal factors leading to their probable failures under this event. Estimates of their replacement costs are,

Table 9 - Reach 2 Public Infrastructure Damage

Pima Mine Road $1,650,000 Sahuarita Road $1,650,000 Duval Mine Road $1,750,000

Total Public Infrastructure Damage

$5,050,000

Railroad Damage

Union Pacific Railroad (UPRR) operates a railroad line between Phoenix and Nogales that runs throughout the study area. This railroad line has two bridge crossings of the Santa Cruz River in Reach 2. In past floods these bridges have experienced damage; in the 1983 flood two spans of one bridge were washed out. Current assessments of these bridges indicate that they are incapable of withstanding the FEMA 100-year flood. In consultation with the Engineering Department of Union Pacific Railroad, the estimated replacement cost of these two crossings is $720,000 per crossing.

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The loss of the bridges is not the only cost that would be incurred by UPRR. Disruption of rail traffic from and to Nogales will be a major cost. Annual UPRR rail traffic between Nogales and Tucson consists of approximately 5 million gross tons of freight. The movement of this freight requires between 2 to 4 trains a day in both directions. If the line between Tucson and Nogales is washed out, UPRR has no other direct link between these cities. To maintain operations from Nogales, UPRR will have to redirect rail traffic south into Mexico, provided an agreement with Mexico can be obtained. Rail traffic that used to come through Tucson to Nogales will be rerouted depending upon its origination direction. Traffic from the west would be rerouted to Calaexio, CA and then south, on Mexican rail lines, into the interior of Mexico before turning north to travel to Nogales, Mexico before crossing the border to Nogales. Traffic from the east would be diverted into Mexico at El Paso, TX and work its way into the interior before heading north to Nogales. The diversions and rerouting through a foreign carrier to maintain operations would cost in excess of $100,000 per day. Restoration of normal operations after a FEMA 100-year flood could easily exceed 3 weeks. Assuming a 3-week restoration period, the additional cost of rail transportation would equal $2.1 million.

Reach 2 Damage Summary

Table 10 summarizes the damages and costs expected to be incurred from the FEMA 100-year flood.

Table 10 - Reach 2 Damage Summary

Category Damage/Cost Total Agricultural Damages $4,713,047 Total Public Infrastructure Damage

$5,050,000

Total Railroad Damage $3,540,000

Total Flood Damages $13,303,047

REACH 3 DAMAGES

The San Xavier Indian Reservation encompasses the land area of Reach 3. Analysis of aerial photographs of this reach suggests that the potential for damages is quite limited. As a result of this preliminary assessment, no further examination of the area was conducted.

REACH 4 DAMAGES

In Reach 4 erosion is the principal cause of damage. Unlike flooding, erosion is a long-term process. Employing a single event to measure the damage from erosion, like the FEMA 100-

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year flood, would not present an accurate portrayal of the true damage potential of erosion. The necessary detailed analysis to examine and characterize the erosion process in Reach 4 is beyond the scope of the current investigation; however, a previous study (Attachment 1) for the University of Arizona (UA) on a limited portion of Reach 4 provides some insight to the significance of erosion in this reach. A direct comparison of damages between the UA study and the current study’s approach is impossible, as erosion damages involve a time component. UA erosion damages are expressed in terms of expected annual averages whereas this study expresses damages in absolute terms. The UA study, notwithstanding the incompatibility, does offer insight into the potential magnitude of erosion damage for a selected portion of the erosion problem in Reach 4. The inventory subject to erosion damage in the UA study is:

Table 11 - University of Arizona Study’s Erosion Inventory

Miracle Mile Bridge $6,200,000 Interstate 10 $1,400,000 Oil & Natural Gas Pipelines $6,000,000 University Facilities & Contents $21,100,000 University Land 700,000 Annual Research & Development Funding $4,400,000

Total $39,800,000

The UA study employed a probabilistic model that tracked the annual movement of the bank towards damageable property over a fifty-year period and converted each future expectant damage to a net present value before annualization. The study found that the net present loss values (for a 50-year period) and average annual erosion damage values to be:

Table 12 - Reach 4 Eroison Damages

Category Net Present Loss Value Average Annual Erosion Damage

Value Physical Property $3,310,128 $236,067 Land $75,908 $5,414 Research & Development $13,871,460 $989,268

Total $17,257,496 $1,230,749

REACH 5 DAMAGES

Until recently, the 100-year floodplain in Reach 5 affected primarily agricultural lands. With the completion of the Lower Santa Cruz Levee Project (Figure 11F – Main Report) in the summer of

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2000, these lands are now protected from flows on the Santa Cruz River (but may still be susceptible to flooding from the Tortolita Fan). With no other identified flood damage categories, total damage in Reach 5 from a 100-year event on the Santa Cruz River is effectively zero.

REACH 6 DAMAGES

Reach 6 is the northern most reach of the study area bordering Pinal County. The reach is composed of agricultural lands and residential development. Residential development in this reach appeared sufficiently large to warrant the analysis of potential structural inundation damages. Two bridges, Trico Road and Trico-Marana Road, cross the Santa Cruz River and have been determined to be susceptible to failure in the FEMA 100-year flood. Based on the methodologies previously presented damages are as follows.

Agricultural Damages

Based on the aerial photographic information of Figure 11G (Main Report), agricultural production acreage is estimated at 4,039 acres. Applying the per acre damage values of:

Cotton Crop Damage $615.60 Irrigation System Damage $259.09 Laser Leveling Costs $320.00

agricultural damages for the FEMA 100-year flood are:

Table 13 - Reach 6 Agricultural Damages

Cotton Crop Damage $2,486,390 Irrigation System Damage $1,046,478 Laser Leveling Costs $1,292,480

Total Agricultural Damages $4,825,348

Public Infrastructure Damage

Assuming the failure of Trico Road and Trico-Marana Road bridges under the FEMA 100-year flood and applying current cost-adjusted comparable bridge construction costs, with the base construction costs derived from the Pima County Flood Control District - Capital Improvement Projects web page (http://www.dot.co.pima.az.us/flood/cip/), public infrastructure damage is:

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Table 14 - Reach Public Infrastructure Damage

Trico Road Bridge $2,350,000 Trico-Marana Road Bridge $2,490,000

Total Public Infrastructure Damage $4,840,000

Structural and Content Inundation Damage

In Reach 6 there are approximately 201 structures. Residential dwellings account for 195 of these structures with the remaining 6 structures being nonresidential. Sixty-seven of the residential structures are construction classified as single-family units with the remaining 128 units construction classified as manufactured housing. The average single-family unit is approximately 1,426 sq.ft. Average depreciated replacement cost per single-family structure is $71,457, with a content value of $39,419. The average manufactured housing unit has depreciated replacement values of $32,623 and $17,943 for structure and contents, respectively. A summary of the structure inventory found in Reach 6 is presented below in Table 15.

Table 15 - Reach 6 Structure Inventory

Total Average

Value Value Type Units Square

feet Structure Content Structure Content

Single-family 67 95,510 $4,801,932 $2,641,063 $71,457 $39,419

Manufactured 128 159,744 $4,175,708 $2,296,639 $32,623 $17,943

Nonresidential 6 45,970 $579,084 $434,313 $96,514 $72,386

Total 201 301,224 $9,556,724 $5,372,015

Inundation damages from the FEMA 100-year flood are (after applying the water surface profiles of Table 2 along with the average first floor elevation derived through the survey work in conjunction with FEMA depth-damage relationships) as follows.

Table 16 – Reach 6 Inundation Damages

Structure Content Total

Single-family housing $784,155 $635,176 $1,419,331

Manufactured housing $419,241 $77,626 $496,868

Nonresidential $118,770 $89,686 $208,456

Total Inundation Damage $1,322,167 $802,488 $2,124,654

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Clean-up Costs

Clean-up costs in Reach 6, based on an average of $3.65 per square foot, are summarized in Table 17.

Table 17 - Reach 6 Clean-up Costs

Clean-up Costs

Single-family housing $348,610 Manufactured housing $583,066 Nonresidential $167,791

Total Clean-up Costs $1,099,467

Emergency Costs

With the extent of the FEMA 100-year flood plain and the duration of the flood, it is expected that all inhabitants of the residential units in Reach 6 will require some temporary relocation. Based on the previous TRA analysis, this cost is anticipated to be in the range of $300,000. The public assistance component of emergency costs is expected to be approximately $1,203,000, including both Federal and non-federal costs at this level of TRA cost.

Table 18 - Reach 6 Emergency Costs

Emergency Costs

Temporary Relocation Assistance $300,000 Public Assistance $1,203,000

Total Emergency Costs $1,503,000

Reach 6 Damage Summary

Table 19 summarizes the damages and costs expected to be incurred from the FEMA 100-year flood.

Table 19 - Reach 6 Damage Summary

Category Damage/Cost

Total Agricultural Damages $4,825,348 Total Public Infrastructure Damage $4,840,000

Total Inundation Damage $2,124,654 Total Clean-up Costs $1,099,467 Total Emergency Costs $1,503,000

Total Flood Damages $14,392,469

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SANTA CRUZ RIVER WATERSHED FLOOD DAMAGE SUMMARY

The previous sections outlined the potential damages from a FEMA 100-year flood by reach. In the following tables these damages have been aggregated by reach and by category for the entire watershed.

Table 20 – Watershed Summary - Damages by Reach

Reach Total Damage

Reach 1 $740,707 Reach 2 $13,303,047 Reach 3 $0 Reach 4 $17,257,496 Reach 5 $0 Reach 6 $14,392,469

Total $45,693,719.00

Table 21 – Watershed Summary - Categorical Damages

Category Damages

Agricultural Damages $10,279,102

Public Infrastructure Damages $9,890,000

Structural Inundation Damages $2,124,654

Clean-up Costs $1,099,467

Emergency Costs $1,503,000

Erosion Damages $17,257,496

Railroad Damages $3,540,000

Total $45,693,719.00

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UNIVERSITY OF ARIZONA

SANTA CRUZ RIVER AT THE WEST CAMPUS AGRICULTURAL CENTER

ECONOMIC ASSESSMENT REPORT

Prepared by:

Simons, Li & Associates, Inc. 3150 Bristol Street, Suite 500

Costa Mesa, CA 92626

January 1999

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UNIVERSITY OF ARIZONA SANTA CRUZ RIVER AT THE WEST CAMPUS AGRICULTURAL CENTER

Table of Contents 1. STUDY PURPOSE AND SCOPE..........................................................................................................................................1

A. BACKGROUND .......................................................................................................................................................................1 B. STUDY PURPOSE AND SCOPE .............................................................................................................................................1 C. STUDY AREA .........................................................................................................................................................................1 D. PRIOR STUDIES AND REPORTS...........................................................................................................................................2

II. ECONOMIC REVIEW OF PREVIOUS REPORTS ...........................................................................................................4

A. ACOE DRAFT RECONNAISSANCE REPORT ......................................................................................................................4 1. Erosion..............................................................................................................................................................................4 2. Economics.........................................................................................................................................................................6

B. PIMA COUNTY - BENEFIT /COST FOLLOW-UP REPORT .................................................................................................7

III. ECONOMIC ANALYSIS.......................................................................................................................................................8

A. METHODOLOGY AND ASSUMPTIONS ...............................................................................................................................8 1. Risk Model........................................................................................................................................................................9 2. The Value of Research & Development.....................................................................................................................10

B. STRUCTURE INVENTORY, LAND, AND GRANTS.............................................................................................................11 1. Structure Inventory.......................................................................................................................................................11 2. Land.................................................................................................................................................................................13 3. WCAC Grants.................................................................................................................................................................13

C. WITHOUT -PROJECT EROSION DAMAGES........................................................................................................................14 1. Structural and Content Damage................................................................................................................................14 2. Land Damage.................................................................................................................................................................16 3. Research & Development Loss ...................................................................................................................................17 4. Without-Project Damage Summary............................................................................................................................18

D. PROJECT JUSTIFICATION...................................................................................................................................................20

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UNIVERSITY OF ARIZONA - ECONOMIC ASSESSMENT REPORT 1

1. STUDY PURPOSE AND SCOPE

A. Background The U.S. Army Corps of Engineers (ACOE) within its Continuing Authorities Program and under the authority of Section 205 of the Flood Control Act of 1948 (PL 80-858), as amended (Flood control), initiated a reconnaissance study of the Santa Cruz River at University of Arizona in 1993. The goal of the study was to examine the Federal interest in the provision of erosion control on the Santa Cruz River between the Grant Road Bridge and the Fort Lowell Bridge, northwest of downtown Tucson. The Section 205 study initiation was in response to a joint request by the University of Arizona and Pima County and the results of a 1991 ACOE Section 14 (Emergency Streambank Protection) study. The Section 14 study could not identify a technically feasible solution of erosion control without causing a downstream translation of the problem. In addition, the streambank protection authority limitation of Section 14 projects could not address the full scope of the problem, which included flood inundation from overbank flows. ACOE did not formally complete the Section 205 reconnaissance study. However, the draft report suggests that no feasible alternative is identifiable. Further, the report indicates that this is the case whether or not the Santa Cruz River hydrology issue between ACOE and Pima County is resolved, (as described in Section II. A). In response to ACOE’s draft report, Pima County Flood Control District prepared a Benefit/Cost Follow-Up report (reproduced in Appendix A) asserting there is an understatement of the economic damages by ACOE and that, perhaps, viable alternatives exist. The current report, therefore, provides additional economic investigation related to the identification of viable alternatives.

B. Study Purpose and Scope The purpose of this Economic Assessment Report is twofold. The first is to reexamine the methodologies and results of the ACOE Section 205 draft report and the Pima County Follow-Up report for validity under current conditions. The second is to reassess the economic viability of erosion control on a National Economic Development (NED) basis. To these ends, the scope of the economic assessment is based on the hydrologic and cost engineering data of the ACOE draft report and the performance of economic field investigations, modeling, and data verification.

C. Study Area The Santa Cruz River is a tributary to the Gila River, which is in itself a tributary of the Colorado River, the largest watercourse in the southwestern United States (Figure 1). The drainage area of

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the Santa Cruz River at Tucson encompasses an area of approximately 2,200 square miles. The headwaters of the Santa Cruz River are located in the Patagonia Mountains to the east and the Huachuca Mountains to the south. The river basin is generally a broad valley interrupted by low hills. The stream gradient of the river in the Tucson area is approximately 18 feet per mile (0.0034). The Santa Cruz River is ephemeral, being dry for long periods of time during the year. Watershed land use consists principally of grazing, irrigated agriculture, and open space. However, in the immediate vicinity of the study area the land is heavily urbanized. Vegetation is sparse in the watershed. It consists mainly of desert flora, creosote, sagebrush, cacti, and palo verde. At higher elevations, pine, fir, juniper and pinyon forest predominate. Soils in the watershed are highly varied. The mountains consist of weathered parent rock, while the valleys consist principally of a heavy cover of gravel, sand, silt, and clays derived from the parent rock. The Santa Cruz River at the West Campus Agricultural Center (WCAC) is a broad meandering channel with high, earthen, vertically-walled banks. WCAC is located on the east bank and is being undercut and eroded away by river flows. Other unprotected properties adjacent to the river in the study area include the Arizona Department of Transportation (ADOT) maintenance facilities, the KTKT radio station, an industrial park, a City park, and a number of utility lines.

D. Prior Studies and Reports The Los Angeles District of ACOE, as previously referenced, initiated a Section 205 Reconnaissance Study of the Santa Cruz River at University of Arizona - Pima County, Arizona in 1993. A final report was not prepared for the reconnaissance study phase, but a draft report was produced (March 1994). In general, the draft report did not identify an economically feasible alternative.

Figure 1 Tucson Vicinity Map

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In response to ACOE’s draft report, Pima County Flood Control District produced a staff report, Section 205 Reconnaissance Report: BENEFIT/COST FOLLOW-UP, Santa Cruz River at University of Arizona, Pima County, Arizona, in December of 1994 that investigated ACOE’s determination of no economically viable alternative. ACOE developed the hydrology for the lower Santa Cruz River in a June 1990 report entitled Hydrologic Documentation for Feasibility Studies, Lower Santa Cruz River, Pinal County, Arizona. This current report, as well as the draft report, utilizes the discharge-frequency relationships developed during the feasibility study. The Federal Emergency Management Agency (FEMA) published a Flood Insurance Study (FIS) on the City of Tucson, which was revised on September 28, 1990. This report contains information on the extent of 100-year flood inundation, flood depths, and methodologies used in its preparation. In developing its material for the study area, FEMA employed a regulatory discharge of 60,000 cfs for the 100-year flood. The United State Geological Survey (USGS) prepared a water supply paper for the region in 1970, and prepared an open file report entitled Channel Change on the Santa Cruz River, Pima County, Arizona, 1936 - 86, in 1993. The open file report contains an analysis of geomorphic changes along the Santa Cruz River. Simons, Li and Associates prepared a Management Plan for the River for the Pima County Department of Transportation and Flood Control in 1986. This report contains geomorphic and hydraulic analyses for the study area.

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II. ECONOMIC REVIEW OF PREVIOUS REPORTS

A. ACOE Draft Reconnaissance Report The ACOE report highlighted a significant difference between the Corps and Pima County’s analysis of the hydrology of the Santa Cruz River. The Corps determined that the 100-year discharge is 33,000 cfs and Pima County determined it to be 60,000 cfs. The report suggests that this difference is immaterial, as the economic results did not support a project under either hydrologic scenario. This conclusion may be unwarranted for two reasons: (1) the implied annual erosion rates shown in Figures 9 through 16 of Appendix B in comparison to the historically observed rates and (2) the economic conclusions of the ACOE draft report do not match the reported data. These reasons are further discussed below.

1. Erosion

In the study area, it is generally agreed that existing long-term erosion processes can be benchmarked to the completion of Interstate10 in 1960. Employing the ACOE methodology as used in the studies of Norco Bluffs, Rillito River, and Tanque Verde Creek; the annual erosion rate is the quotient of the present extent of erosion from the benchmark year over the length of time. Most observers agree that little, if any, erosion occurred between the years 1960 and 1977. If this is indeed the case, the lateral extent of erosion can be assumed to be the sum of the erosion event data presented in Table 2 of the ACOE report. The base year for the ACOE study was 1994, making the time frame 34 years. Reach J of Table 3 of Appendix B reports total erosion of 302 feet which would yield an average annual erosion rate of 8.88 feet. The appropriateness of the erosion-frequency function of Reach J (Figure 10 of Appendix B) can be verified by integration of the function. The result of the integration should yield a figure close to 8.88 if the function is representative of the process. Direct integration of the erosion-frequency function is not possible without the formula to the function. However, an approximation of the integration can be calculated using HEC’s EAD model and frequency-erosion pairs from Figure 10 of Appendix B. The expected annual rate of erosion that was calculated by the EAD model is 3.45 feet, using 10 pairs of erosion-frequency data from the above figure. The significant discrepancy between observed and the erosion-frequency function relates to ACOE’s pair references. A simple rotational shift of the erosion-frequency function, as shown in Figure 2 below, reflecting Pima County’s suggestion that the ACOE’s 500-year erosion is really the 100-year level, produces a significantly different outcome. Using the same frequency points, but with new erosion levels based on the Pima County rotation, the HEC EAD model produces an estimate of annual erosion of 8.74 feet. Table 2.1, below, shows the historical erosion rate and the EAD

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computation based on the ACOE functions, as well as the Pima County rotational shift.

Table 2.1 Annual Erosion Rates (in feet)

Reach Historical Rate ACOE EAD Rate Pima County EAD Rate

I 9.65 6.06 10.38

J 8.88 3.45 8.78

K 8.41 3.48 8.85

M 6.47 2.76 7.37

N 6.06 2.68 7.13

P 4.47 0.50 0.99

II 12.47 1.53 3.82

JJ 14.41 1.59 3.53

The Pima County annual erosion rates correlate with the historical rates more accurately through Reach N. Both ACOE and Pima County coincide poorly with the historical process between Reaches P and JJ. Examination of Figure 7 of the Appendix B may give some insight into why ACOE and Pima County’s rates correlate so poorly in this area. Reach P is one of the outermost points of an inward bend of the river as it transitions to an outward bend in Reaches II and JJ. This transition area could be a factor in the poor estimate of Reach P. However, as Reaches II and JJ are just mirror opposites of the inward bending reaches, the poor performance in these reaches could possibly be a function of their basic derivation. An error in the basic derivation of the erosion-frequency function would translate into the Pima function without correction, since the Pima County function is just a rotational shift of the ACOE function. In summary, the implied erosion rates of Figures 9 through 16 of the ACOE report appear to underestimate what has been historically observed. Further, the simple rotational shift based on Pima County’s version of the frequency-discharge relationship produces a tighter fit with the historical data, except for the transition area.

2. Economics

The documentation presented in the ACOE report does not allow for a full audit trail of the methodology and process by which economic damages were assessed. However, the information presented suggests an error in the economic analysis. Table 5 of the Economic Analysis of the ACOE report presents damages associated with a given event from the current bank position. From the Economic Analysis’ text and Figure 6 of the ACOE report, the following frequency-damage function is derived:

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Table 2.2 ACOE Frequency-Damage Function

20-year 29-year 50-year 100-year 200-year 500-year

$0 $1,600,000 $1,614,619 $6,690,850 $7,283,833 $10,811,003

The equivalent annual damage for the above function is $149,920. This equivalent annual damage is for a static process. The bank does not gradually erode. Damage is only counted when a flood event sufficient to erode all the distance from the bank to the structure in a single event occurs for a given structure. In comparison, the ACOE reports that its model of random continuous erosion yields an expected annual erosion damage of $130,675. This cannot be correct since a singular event-based result cannot be greater than the result for the continuous erosion model. It is impossible to explain why the ACOE economic model is in error because a full description of the economic model is typically not included in this type of report. It is sufficient however, just to note that any findings based on the ACOE economics are misleading.

B. Pima County - Benefit/Cost Follow-Up Report The Benefit/Cost Follow-Up Report by Pima County states that the ACOE did an inadequate analysis on the measurement of values, and that the ACOE methodology in assessing the value of the University’s research and development (R&D) does not fully reflect the NED value of the R&D. In a memorandum by the Chief Appraiser for the Pima County Real Property Division (Attachment 1 of the Pima County report) it is suggested that the “true” NED value of land in the study area is $11,000 per acre, rather than the ACOE’s reported value of $4,000. The ACOE economic analysis does not state how its land value was derived. However, the analysis does suggest that land was treated as agricultural land since the R&D crops of the University were handled as simple commercial crops. Typical agricultural land in the general area of the study may have a value near the ACOE’s estimate, but the study area is not located in an agricultural area. Its zoning as stated by the Chief Appraiser, is residential with the City of Tucson’s Santa Cruz Area Plan showing the future conversion to commercial/industrial. It is reasonable to conclude that the NED value of the land, given its present and potential future zoning, would be more in-line with Pima County’s valuation. The Pima County report also indicates that the ACOE’s evaluation of the R&D crops by a commercial net income valuation of $400 per acre incorrectly characterizes the nature of these crops. Pima County’s contention that ACOE’s valuation and methodology are inaccurate has some value, since these crops are not produced for the market, but are produced for a national high-value research effort.

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III. ECONOMIC ANALYSIS

A. Methodology and Assumptions The following economic assessment is based on the Risk & Uncertainty Methodology for erosion as presented in the ACOE report for Tanque Verde Creek, Arizona. The derivation of the cumulative probability density function is based on the rotational shift of the frequency-discharge function. This function has the general form of:

And having the specific form of:

Table 3.1 Reach Cumulative Probability Density Function

Reach min max Cumulative Probability (erosion in feet)

0.5 0.60 0.7 0.8 0.9 0.95 0.98 0.99 0.998

I 0 407.0 .00001 0.25 .78 2.40 10.0 35.0 150 370 370

J 0 341.0 .00001 0.23 .58 1.75 8.5 30.0 130 310 310

K 0 352.0 .00001 0.25 .60 1.90 8.5 30.0 125 320 320

M 0 275.0 .00001 0.27 .62 1.70 8.0 28.0 105 250 250

N & JJJ 0 264.0 .00001 0.24 .60 1.60 8.0 26.0 105 240 240

P 0 24.2 .00001 0.20 .32 .75 2.1 4.7 12 22 22

II 0 126.5 .00001 0.24 .53 1.45 5.3 15.5 54 115 115

JJ 0 121.0 .00001 0.23 .50 1.30 4.9 14.5 47 110 110

Applying the specific forms shown above in an Excel spreadsheet with a @RISK add-in, a 20,000 iteration simulation of each of the cumulative probability density functions produced the following mean and standard deviation for each reach.

CUMUL(min,max,{ ,..., },{ ,..., })x x p pn n1 1

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Table 3.2 Mean Erosion Rate and Standard Deviation by Reach

(in feet)

Reach Mean Standard Deviation

Reach I 11.228 49.223

Reach J 9.498 41.492

Reach K 9.556 42.329

Reach M 7.954 33.572

Reach N 7.704 32.432

Reach P 1.054 3.208

Reach II 4.102 15.836

Reach JJ 3.800 14.876

1. Risk Model

The Risk Model was constructed as follows: a. The base distance of a structure from the river’s bank was measured from

scaled aerial photos and assigned to the appropriate Reach. a. The depreciated value of the structure was determined through the use of

Marshall & Swift Evaluation System, with data supplied by the University of Arizona, the Arizona Department of Transportation (ADOT), or other sources.

b. Content value was assessed through data supplied by the University of Arizona

or by interview with the structure’s owner. c. A condemnation zone was determined thereby designating where the loss of the

use of the structure will occur and where contents are not subject to loss. d. An annual reach erosion spreadsheet based on the probability density function

calculated the year at which erosion damage occurs for a Net Present Value (NPV) determination of developed structures in a given Reach by tracking the incremental and cumulative erosion over a fifty-year life-cycle.

e. The base year for the NPV analysis was 2001 and the current ACOE discount

rate of 6? percent was employed. f. The mean NPV of erosion damage by Reach was determined by simulating

each Reach’s annual erosion spreadsheet 10,000 times. Erosion damage for land, pipelines, Interstate I-10, and utilities were determined in a similar manner as structures.

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2. The Value of Research & Development

ACOE’s engineering regulation ER 1105-2-100 [31 Oct 97], Section 5-8 b. (1) (b) states: “Beneficial effects in the NED account are increases in the economic value of the

national output of goods and services from a plan; the value of output resulting from external economies caused by a plan; and the value associated with the use of otherwise unemployed or under-employed labor resources.”

In Section 5-8 b. (2) Goods and services: General measurement standard, the ER defines the measurement standard as: “The general measurement standard of the value of goods and services is defined

as the willingness of users to pay for each increment of output from a plan. Such a value would be obtained if the “seller” of the output were able to apply a variable unit price and charge each user an individual price to capture the full value of the output to the user.”

The R&D of the University of Arizona is not a traditional market good. The “goods” of R&D are not normally subject to the economic forces of supply and demand insofar as they’re seeking a market-clearing price. R&D deals primarily with a single output contracted between a buyer and seller. Through the give-and-take of negotiations, the negotiated price of R&D funding is more likely to capture the full value from the user. In addition to its nonmarket nature, R&D is not readily transferable to another institution or site. Much of the R&D work at the University of Arizona involves long-term studies that cannot be transferred without experiencing sizable and potentially insurmountable time delays and costs, notwithstanding the need to acquire key research staff members from the University of Arizona. The R&D work at the University of Arizona appears to satisfy ACOE’s guidance on a unique non-transferable product. Therefore, the change in NED benefit can be estimated by comparing the net present value of the without- and with-project R&D funding streams.

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B. Structure Inventory, Land, and Grants

1. Structure Inventory

The study area is shown in the aerial photograph of Figure 3. The inventory of structures within the study area is detailed in Table 3.3. As indicated in Table 3.3, structural and content values for the study area are $18,848,100 and $2,284,550, respectively. The values for Miracle Mile Bridge and Interstate - 10 are based on consultations with the Arizona Department of Transportation (ADOT). According to the Bridge Group of ADOT with consideration to the current construction cost for the ADOT Valley Project (Appendix C), the base square footage cost for the Miracle Mile Bridge is $56.78 plus fourteen (14) percent for construction contingencies and engineering. At 95,000 square feet, Miracle Mile Bridge’s replacement cost is approximately $6,150,000. In the case of Interstate - 10, ADOT estimated the replacement cost at $15,148,000 per mile. The potential damage to Interstate - 10 is $1,434,000, as approximately 500 feet of the Interstate is subject to erosion. Kinder Morgan operates and maintains one 8-inch and one 6-inch high pressure refined petroleum product pipelines crossing the Santa Cruz River south of Ft. Lowell Road in the study area. The products conveyed in the pipelines consist of various grades of gasoline, diesel and military jet fuels. The average daily throughput of the 8-inch pipeline is 44,000 barrels per day (bbls/day) and the 6-inch pipeline is 8,000 bbls/day. The 8-inch facility transports various grades of refined petroleum product, which originate from refineries in Texas and New Mexico to the greater Phoenix area. The 6-inch pipeline is used to convey refined products that originate from refineries in the Los Angeles basin to the greater Tucson area. The replacement of the pipeline crossing would be of a directional bore method for 3,000 feet of pipeline at an estimated cost of $1.5 million for each pipeline, for a total cost of $3 million. Southwest Gas maintains two pipelines in the general area as those of Kinder Morgan. It is estimated that the replacement of these pipelines would be similar to those of Kinder Morgan. Therefore, the value of the Southwest Gas pipelines is set at $3 million. The value of the Tucson Electric high tension electric lines was determined to be consistent with the previous ACOE study and is set at $105,000 per electric pole. Data on the structures of the University of Arizona’s West Campus Agricultural Center was prepared by the Tucson Area Agricultural Center (TAAC), (see, Appendix D). The estimates by TAAC for structure values were verified and are generally consistent with depreciated replacement cost estimates developed through the Marshall & Swift Valuation Service. No analysis was made to estimate content values for omitted entries by TAAC, except for residence quarters where the content value was set at 50 percent of the structure value. The omission of these content values was deemed minor and insignificant in potential project justification.

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Table 3.3 Study Area - Structure Inventory

Depreciated Replacement Value

($, 1998)

Reach Structure Identity Distance from Bank (feet) Square Footage Structure Content

I #2321 Residence 170 1,428 101,700 50,850

I Main WCAC Well 220 107,500

I Water Storage/Pumping 110 3,520 329,100

I Waste Pumping Station 140 403,900

I Interstate 10 500 1,430,000

J #2327 Shrimp Virus Lab 120 1,896 110,000

J #2323 AVDL Necropsy Building 350 2,091 339,300 107,000

J #2324 AVDL Building 250 14,040 2,143,000 693,000

J Miracle Mile Bridge 880 95,000 6,150,000

K #2333 AVDL Shop & Storage 110 1,120 77,600

K #2334 Aquaculture Building 200 1,024 70,900

K #2335 Poultry House 240 1,024 70,900 36,000

K #2336 Aquaculture Building 280 1,024 70,900

K New Poultry Building 280 1,200 126,000 18,000

M #2340 Aquaculture Building 210 1,320 91,400 28,000

M Gas Line Network 120 63,000

M Tucson Electric High Tension Lines 110 210,000

M Tucson Electric High Tension Lines 210 210,000

N #2341 WCAC Shop 190 1,455 82,700 31,000

N #2342 WCAC Storage 270 1,007 70,000 42,000

N #2343 Hydrology Storage 480 576 40,000 850,000

P #2346 Domestic Well #2 240 72,000

P Pond Compound 130 25,000 141,500

II #2309 Feed Mill Shop 670 1,174 61,500 7,100

II #2310 Feed Mill 700 5,021 413,400 83,000

II #2312 Hay Storage 700 4,040 62,500 28,000

II #2313 Scales, Pens, Chutes 680 3,400 35,000

II #2314 Feeding Pens 630 31,320 56,000

II #2317 Animal Holding Facility 880 4,280 4,300

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Table 3.3 Study Area - Structure Inventory

Depreciated Replacement Value

($, 1998)

Reach Structure Identity Distance from Bank (feet) Square Footage Structure Content

II KTKT Radio Station 360 5,000 950,000 200,000

JJJ #2305 Residence 600 1,569 107,200 53,600

JJJ #2350 Fishery Laboratory 430 800 55,200 21,000

JJJ #2351 Fishery Storage 320 600 18,000 4,000

JJJ #2352 Fishery Well 370 52,000

JJJ Fishery Compound 330 26,400 21,600 32,000

JJJ Santa Fe Pacific Petroleum Pipeline 25 1,500,000

JJJ Southwest Gas Pipeline 53 3,000,000

TOTAL 18,848,100 2,284,550

2. Land

The WCAC facility contains approximately 64 acres. The value of land employed in the economic analysis was set at $11,000 per acre in accordance with the discussion in the Pima County report. This value consisted of the net loss in land value between non-eroded and eroded (channel bottom) land. Land values eroded outside of the WCAC facility were not considered in the economic analysis nor were potential land intensification gains analyzed for project benefits.

3. WCAC Grants

TAAC has prepared a summary of research, education, and public support activities, which occur at the WCAC (see Appendix D). TAAC reports that current WCAC grants total $14,791,030. Further TAAC estimates the value of grants over the next five years to total $22,164,950, or approximately $4.4 million per year. For the economic analysis of erosion damage, an annual grant value of $4.4 million was assumed to exist provided that WCAC was operational.

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C. Without-Project Erosion Damages

1. Structural and Content Damage

The structures of Table 3.3 were separated by reach, and each structure was subjected to the appropriate reach cumulative probability erosion density function of Table 3.1. The @RISK model tracked the annual movement of the bank toward the structure over the fifty-year period of the analysis. The model calculated the future time period at which erosion damaged each structure, if damage occurred, for each structure in a reach. Each occurrence of future structure damage was then converted to a net present value (NPV), with NPV value for all structures in a reach being totaled. Concurrent with the structural analysis, the model determined if erosion had proceeded close enough to a structure (a condemnation zone - generally 10 to 15 feet) where it was assumed that contents would be removed from the structure and would not be subject to erosion. Contents were assumed to be damaged if the prior bank position was outside of the condemnation zone and the current annual erosion event was estimated to be great enough to have caused structural damage. Content damage was time dated and converted to NPV - like structures. The fifty-year time period of the analysis was repeated 10,000 times for each reach to develop a distribution of the NPV of erosion damage by reach. These distributions are shown in Table 3.4. The mean NPV damage for structures and contents is $3,310,128. Annualizing this mean NPV value yields an average annual erosion damage value of $236,100.

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Table 3.4 NPV Statistics by Reach, Combined Structure and Content Erosion Damage ($, 1998)

REACH I REACH J REACH K REACH M REACH N REACH P REACH II REACH JJJ BRIDGE I-10 PIPELINES RADIO ELECTRIC TOTAL

Minimum 0 0 0 0 0 0 0 0 0 0 0 0 0 0

Maximum 95,158 3,174,082 423,205 170,667 1,107,556 35,023 85,734 331,468 5,037,868 1,338,012 4,210,527 771,687 392,983 17,173,970

Mean 31,365 723,606 109,494 44,939 87,230 63 60 20,373 71,231 151,916 1,945,009 14,033 110,809 3,310,128

Std Deviation 26,778 784,198 105,572 43,222 149,678 834 1,575 36,965 264,124 229,142 1,164,552 48,319 99,052

Skewness 1 1 1 1 18 20 35 29 7 2 0 6 1

Kurtosis 2 4 4 3 75 584 1,405 180 67 8 2 59 3

5% 0 3,466 0 0 0 0 0 0 0 0 0 0 0 3,466

10% 0 8,227 5,001 0 0 0 0 0 0 0 384,411 0 8,078 405,717

15% 4,468 18,270 11,284 4,125 0 0 0 0 0 0 674,430 0 15,705 728,282

20% 6,659 56,576 19,872 7,504 2,606 0 0 0 0 0 888,251 0 23,405 1,004,873

25% 8,688 130,486 27,710 10,529 3,634 0 0 0 0 0 1,057,543 0 31,411 1,270,001

30% 11,335 173,310 36,000 14,096 7,272 0 0 0 0 0 1,220,133 0 39,707 1,501,853

35% 13,837 220,758 44,654 17,779 9,488 0 0 0 0 0 1,378,027 0 48,635 1,733,178

40% 16,891 272,268 53,875 21,726 13,186 0 0 1,420 0 0 1,553,082 0 59,012 1,991,460

45% 20,620 335,040 64,307 26,036 18,758 0 0 1,794 0 48,156 1,697,895 0 69,758 2,282,364

50% 25,172 406,909 75,123 31,119 25,009 0 0 4,341 0 62,829 1,883,599 0 82,418 2,596,519

55% 28,752 504,629 85,852 36,983 31,013 0 0 6,712 0 76,698 2,026,278 0 97,269 2,894,186

60% 32,842 622,285 100,077 42,243 40,619 0 0 10,741 0 100,067 2,157,533 0 111,103 3,217,510

65% 37,513 750,849 118,282 50,427 51,300 0 0 13,853 0 122,157 2,413,661 0 128,029 3,686,071

70% 42,484 909,641 137,196 58,902 64,481 0 0 18,331 0 159,376 2,643,647 0 145,275 4,179,333

75% 48,942 1,095,469 162,464 67,280 111,297 0 0 23,785 0 207,935 2,825,398 0 165,571 4,708,141

80% 55,903 1,337,299 190,562 79,412 146,576 0 0 30,954 0 271,289 3,019,644 0 189,119 5,320,758

85% 63,854 1,632,514 232,393 93,813 195,629 0 0 44,651 0 353,946 3,326,321 0 220,329 6,163,450

90% 72,936 1,992,899 279,708 114,523 269,622 0 0 63,142 236,562 461,787 3,686,245 47,676 263,704 7,488,804

95% 83,309 2,471,057 346,675 139,804 397,481 0 0 96,278 459,945 643,906 3,939,674 86,733 321,918 8,986,780

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2. Land Damage

The assessment of land damage from erosion utilized the cumulative probability erosion density functions of Table 3.1 and aerial photographic measurements of the width of each reach. The net value loss of land from erosion was assumed to be proportional at all levels, that is, each square foot of lost land was valued at $0.2525. This land value is based on the residual land value of the Pima County Report ($11,000 per acre). The model generated a stream of the annual land lost and its value and converted the annual value stream to a net present value over the fifty-year analysis period. This process was repeated 10,000 times to produce the estimated annual value of land loss due to erosion from the Santa Cruz River. The result of this process is shown in Table 3.5.

Table 3.5 NPV Statistics for Land Loss

Value of Land Loss ($, 1998)

Minimum 22,233

Maximum 189,220

Mean 75,908

Std Deviation 23,951

Skewness 1

Kurtosis 3

5% 42,120

10% 46,980

15% 51,622

20% 55,157

25% 58,333

30% 61,508

35% 64,100

40% 66,941

45% 69,903

50% 72,983

55% 76,261

60% 79,224

65% 82,734

70% 86,930

75% 91,044

80% 95,306

85% 100,688

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Table 3.5 NPV Statistics for Land Loss

Value of Land Loss ($, 1998)

90% 108,255

95% 119,243

3. Research & Development Loss

As documented in Section III.A.2, the unique nature of R&D at the University of Arizona affords the economic analysis the ability to measure the NED loss through the examination of future research funding by the comparison of the without-project annual stream to a non-erosion with-project condition. The NED loss is the change in value of the willingness to pay on a net present value basis between these conditions.1 Current R&D grants at WCAC total $14,791,030 and the 5-year projected grant value is $22,164,950 according to TAAC. If it is assumed that this level of funding continues throughout time, the average annual grant value, hence the willingness to pay, is approximately $4.4 million. In consultation with TAAC, it was determined that continued erosion of 200 feet at the southern end of WCAC would be sufficient to destroy the waste pumping station, main WCAC well, the water storage/pumping facility, and about half of WCAC structures, and would effectively end R&D activity at WCAC. The R&U analysis considers this 200-foot marker as the point where funding ceases, and the change in NPV between the erosion and non-erosion condition at WCAC is shown in Table 3.6, “R&D NED Loss - Erosion at WCAC”, below. The analysis indicates the mean net present value R&D NED loss is $13,871,460. The R&U analysis also indicates that there is a 21.77% chance that there would be no R&D NED loss.

1

Analytically the R&U model considers the probability that the WCAC is rendered inoperable prior to the construction of a possible solution and the NPV of the stream of funding in the without erosion condition has been adjusted to reflect this possibility.

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Table 3.6 R&D NED Loss - Erosion at WCAC

($, 1998) Erosion Non-erosion NED Loss1

Minimum 0 0 0

Maximum 61,983,390 61,983,390 57,866,430

Mean 45,062,350 58,933,810 13,871,460

Std Deviation 18,667,370 13,406,100 15,917,020

Skewness (1) (4) 1

Kurtosis 3 18 3

5% 4,116,959 61,983,390 0

10% 11,573,410 61,983,390 0

15% 21,053,950 61,983,390 0

20% 28,820,080 61,983,390 0

25% 35,181,830 61,983,390 614,423

30% 40,393,150 61,983,390 1,652,044

35% 43,332,600 61,983,390 2,769,815

40% 47,069,980 61,983,390 4,228,149

45% 50,131,520 61,983,390 5,606,708

50% 52,639,420 61,983,390 7,289,591

55% 54,693,800 61,983,390 9,343,977

60% 56,376,680 61,983,390 11,851,880

65% 57,755,240 61,983,390 14,913,410

70% 59,213,580 61,983,390 18,650,790

75% 60,331,350 61,983,390 21,590,240

80% 61,368,970 61,983,390 26,801,570

85% 61,983,390 61,983,390 33,163,310

90% 61,983,390 61,983,390 40,929,440

95% 61,983,390 61,983,390 50,409,980 1 Note: The NED loss is not the difference between the percentile figures. The interpretation of the Table is there is a

50% chance that the NPV future grants will be less than $52.6 million in the erosion case, a 5% chance the NPV will be less than $4.1 million in the erosion case, and so on. The R&U analysis indicates that there is a 4.92% chance that the WCAC will be destroyed prior to the potential construction of a project. This can be observed through the comparison of the mean and maximum NPV values of the non-erosion case.

4. Without-Project Damage Summary

Table 3.7, Summary of NED Damages, summarizes the damages of Tables 3.4 through 3.6. The mean NPV NED loss from erosion in the study area is $17,257,496. Amortizing this value over 50-years at the ACOE Federal discount rate of 6? percent yields an annual value of $1,230,749.

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Table 3.7 Summary of NED Damages

($, 1998) Structures Land Grant Total

Minimum 0 22,233 0 22,233

Maximum 17,173,970 189,220 57,866,430 75,229,620

Mean 3,310,128 75,908 13,871,460 17,257,496

5% 3,466 42,120 0 45,586

10% 405,717 46,980 0 452,697

15% 728,282 51,622 0 779,904

20% 1,004,873 55,157 0 1,060,030

25% 1,270,001 58,333 614,423 1,942,757

30% 1,501,853 61,508 1,652,044 3,215,405

35% 1,733,178 64,100 2,769,815 4,567,093

40% 1,991,460 66,941 4,228,149 6,286,550

45% 2,282,364 69,903 5,606,708 7,958,975

50% 2,596,519 72,983 7,289,591 9,959,093

55% 2,894,186 76,261 9,343,977 12,314,424

60% 3,217,510 79,224 11,851,880 15,148,614

65% 3,686,071 82,734 14,913,410 18,682,215

70% 4,179,333 86,930 18,650,790 22,917,053

75% 4,708,141 91,044 21,590,240 26,389,425

80% 5,320,758 95,306 26,801,570 32,217,634

85% 6,163,450 100,688 33,163,310 39,427,448

90% 7,488,804 108,255 40,929,440 48,526,499

95% 8,986,780 119,243 50,409,980 59,516,003

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D. Project Justification The ACOE report indicates that the gross investment cost of providing erosion protection to the study area was $5,856,479 (1994 price level). Amortization of the gross investment at the current ACOE Federal discount rate and 50-year schedule yields an annual charge of $417,665. Inclusion of annual maintenance ($5,000) raises the annual cost to $422,665. The Benefit/Cost ratio is 2.9, with mean annual benefits of $1,230,749 and without updating costs to current levels. Further examination of Table 3.7 indicates a greater than 60% chance that benefits exceed costs.

Table 3.8 B/C Ratio & Net Benefits

Benefits Costs Net Benefits B/C Ratio

$1,230,749 $422,665 $808,084 2.9

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[Appendices intentionally deleted]

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U.S. Army Corps of Engineers South Pacific Division Los Angeles District

SANTA CRUZ RIVER WATERSHED

MANAGEMENT STUDY

PIMA COUNTY, ARIZONA

Appendix C3 Recreation Demand Assessment

August 2001

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Appendix C3 - C3-i August 2001 Recreation Assessment

Table of Contents

List of Tables ............................................................................................................................................ i

Introduction..............................................................................................................................................1

Study Area ..........................................................................................................................................1 Definitions ...........................................................................................................................................3

Proposed Recreational Features..............................................................................................................5

Recreational Demand & Benefits .............................................................................................................7

Recreational Demand ..........................................................................................................................8 Park Demand ..................................................................................................................................8 Multi-Purpose Trail Demand ............................................................................................................9 Park Benefits...................................................................................................................................9 Multi-Purpose Trail Benefits...........................................................................................................10 Total Annual Recreational Benefits................................................................................................11

LIST OF TABLES

Table 1 - Park Demand...............................................................................................................8 Table 2 - Multi-Purpose Trail Capacities .....................................................................................9 Table 3 - Unit Day Values: Parks .............................................................................................10 Table 4 - Unit Day Values: Multi-Purpose Trails.......................................................................11 Table 5 – Multi-Purpose Trail Values ........................................................................................11 Table 6 – Total Annual Recreational Benefits ...........................................................................12

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Appendix C3 - C3-1 August 2001 Recreation Assessment

INTRODUCTION

The Tucson metropolitan area has witnessed increasing population growth over the past few decades. The metropolitan area is expected to continue growing at approximately 2.5 percent annually for the next several years. The Tucson Metropolitan Standard Area (MSA) is estimated by the U.S. Census Department to have a current (1999) population of over 800,000. As the population increases, continuing to provide open space corridors linking parks and recreational facilities will be critical. Pima County Flood Control District has been actively constructing River Parks along the major washes and drainage ways in the watershed for approximately fifteen years. The City of Tucson adopted the first Master Plan for the Santa Cruz River Park in 1976. This Plan was updated in 1982 and again, by Pima County in 1996. Today, much of the metropolitan area’s major watercourses are surrounded by urbanization and development pressures continue to push closer to the watercourses. The existing River Parks system has been designed with an emphasis on the recreational aspects of a linear River Park. Ordinances, regulations and special conditions to preserve and/or mitigate significant vegetation, archaeology and integration of cultural features from surrounding neighborhoods have also assisted in preserving Tucson’s heritage. The result of this effort has been the construction of over twenty miles of public trails and access to other recreational facilities in the Tucson Basin. While several reaches of the Santa Cruz River Park have been constructed, there are critical linkages along the existing river park sections that have not been constructed due to funding, right-of-way, jurisdictional issues or lack of bank protection. The purpose of this assessment is to present an analysis of various components for inclusion into the complete Santa Cruz River Park.

Study Area

The Santa Cruz River is a tributary to the Gila River, which is itself a tributary of the Colorado River, the largest watercourse in the southwestern United States. The drainage area of the Santa Cruz River at Tucson encompasses an area of approximately 2,200 square miles. The headwaters of the Santa Cruz River are located in the Patagonia Mountains to the east and the Huachuca Mountains to the south. The river basin is generally a broad valley interrupted by low hills. The stream gradient of the river in the Tucson area is approximately 18 feet per mile (0.0034). The Santa Cruz River is ephemeral, with flow in the River only following precipitation events. Watershed land use consists principally of grazing, irrigated agriculture, and open space. However, in and around the immediate vicinity of City of Tucson the study area is heavily urbanized. Vegetation is sparse in the watershed. It consists mainly of Sonoran desert

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Appendix C3 - C3-2 August 2001 Recreation Assessment

flora: creosote, sagebrush, cacti, and palo verde. At higher elevations, pine, fir, juniper and pinyon forest predominate. Soils in the watershed are highly varied. The mountains consist of weathered parent rock, while the valleys consist principally of a heavy cover of gravel, sand, silt, and clays derived from the parent rock. Within the scope of this study, the upper reach begins at the Santa Cruz County line and the lower reach ends at the Pinal County line. The portion of the Santa Cruz River on the San Xavier Indian Reservation is not included in this recreation analysis (Reach 3). The study area, for purposes of analysis, is divided along the reach definitions that are described and depicted (Figure 1A) in the Main Report. The upper reach of the Santa Cruz River (Reaches 1 and 2), with the exception of Green Valley and the Town of Sahuarita, is largely agricultural or undeveloped land. There is no major bank stabilization between the Santa Cruz County line and Irvington Road, with the exception of bridges where major roadways cross the Santa Cruz River. The two major land uses adjacent to the Santa Cruz River in the Green Valley area are residential and open space/park/golf course. This upper reach of the Santa Cruz is predominantly rural in character. As indicated above, the Santa Cruz River flows through the San Xavier Indian Reservation in Reach 3 and is not included in this assessment of recreation potential. As the Santa Cruz River winds toward the City of Tucson limits (Reach 4), land uses adjacent to the watercourse begin to exhibit a transitional or suburban character. Between Valencia and Silverlake Road, residential development increases. A portion of the River Park system has already been constructed between Irvington Road and Ajo Way adjacent to the Santa Cruz River. The most developed River Park segment along the Santa Cruz River is between Silverlake Road and Grant Road (Reach 4). This park development entails approximately 3½ miles of linear park development on both sides of the riverbanks. This development has been in place for nearly fifteen years. Surrounding land use patterns are changing between Miracle Mile and Twin Peaks Road (Reaches 4 and 5). Significant residential development has been and is under development in the Continental Ranch area, between Cortaro Farms Road and Twin Peaks Road, as well as in many other areas adjacent to the watercourse. The northern portion of the reach receives effluent discharge from the Roger Road Wastewater Treatment Facility, and typically has a surface flow year round within the channel. Along the lower Santa Cruz River, northern Reach 5 and Reach 6, from Avra Valley Road to the Pinal County line, the adjacent land use is predominantly agricultural. There is no bank stabilization and the river meanders through a wide channel. This reach receives effluent

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Appendix C3 - C3-3 August 2001 Recreation Assessment

discharge from the Roger Road Wastewater Treatment Facility in Reach 4 and the Ina Road Wastewater Treatment facility located in Reach 5, and typically has a surface flow year round within the channel.

Definitions

Three basic classifications have been established for the Pima County River Park System, (Pima County, 1996) which are employed in this analysis. The three categories, from most developed to the least developed are: River Park, River Path and the River Trail, as depicted in Figure 1. According to the Pima County River Park System, there are nine major elements in classifying the degree of development within the park system. The most critical elements are bank stabilization measures, right-of-way ownership and width and extent of trail development. The River Park is the most extensively developed category within the Park system. The ultimate build-out of a River Park section would include sufficient right-of-way to include a minimum of two pathways, one paved (min. 12’ wide), the other decomposed granite, planting areas, restrooms, drinking fountains, and grade separated intersections at roadway crossings. This higher level of development is generally designed for location in central metropolitan Tucson to promote alternative modes of commuter traffic and provide open space/recreational opportunities. The River Path category is the intermediate system. It has been proposed along the fringes of developed urban areas or along less intensively developed urban areas. This classification does not require bank stabilization, although bank stabilization is preferred. A minimum of one 12’ wide path is required; and, depending on the location of the system, the path may be paved or developed with decomposed granite. The River Path is also identified in areas that provide linkages and alternate routes between undevelopable sections along the drainage courses. The least developed category is the River Trails classification. This is proposed in areas where there is no bank stabilization and bank stabilization is not seen within the near future. The areas of River Trails are largely within the rural areas of Pima County. These are areas where there are little cost to benefit returns of developing a more urbanized system.

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Appendix C3 - C3-4 August 2001 Recreation Assessment

Figure 1

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Appendix C3 - C3-5 August 2001 Recreation Assessment

PROPOSED RECREATIONAL FEATURES

The following recreational facilities have been proposed for the Santa Cruz River Park System; which if implemented would establish essential linkages to existing facilities for the unification of the River Park System. The facilities are broken out in terms of potential projects in the Watershed Plan (see Section 11 – Main Report), and by Reach. Floodprone land acquisition (Reaches 1 and 2): Reach 1

• The addition of 10 miles of river trail to the west bank between the Santa Cruz County Line and Continental Road Bridge. This river trail will link up with 6 trails that are part of the Eastern Pima County Trail System Master Plan (EPCTSMP). These include #8-Santa Cruz River, #83-Continental Road, #80-Madera Canyon Wash, #78-Esperanza Wash, #281-Arroyo 17, and #289 -Power Line Loop.

Reach 2

• The addition of 10 miles of river trail to the west bank between Continental Road

Bridge and Pima Mine Road Bridge. The river trail will link up with 6 trails that are part of the EPCTSMP. These include #8-Santa Cruz River, #76-Dawson Road/Helvetia Wash/Jane’s Wash Loop, #83-Continental Road, #86-Madera Canyon Road, #292-Wrest Loop Green Valley/Arroyo 17, and #294-West Toro Trail.

Paseo de Las Iglesias/COT’s Rio Nuevo and Multiple Benefit Water Use Projects (Reach 4)

Reaches 4 and 5

The proposed construction of the Paseo de las Iglesias/City of Tucson’s (COT) Rio Nuevo/COT’s Multiple Benefit Water Use Projects which include: • 1 mile of river trail on the west bank from Los Reales Road to Valencia Road. • 2 miles of river path on both banks from Valencia Road to Irvington Road. • The construction of a 50-acre park with mesquite bosque and on the east bank

between Irvington and Ajo Way. • 1.5 miles of river park on both sides between Ajo Way and Silverlake Blvd with a

potential link to 4-mile long Tucson Diversion Channel bike trail that connects to the Ajo detention basin.

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• A 6-acre downtown gateway water feature park. • The development of a 6.5 miles of seasonal/continuous low flow in mainstem Santa

Cruz from Valencia Road to Saint Mary’s Road. The concept should increase the value of the river parks by introducing riparian vegetation into the river channel. It also includes up to 12 different viewing areas at six different water-release points along the way

Grant to Fort Lowell Bank Protection (Reach 4)

• 1.5 miles of river park on both sides of river between Grant to Fort Lowell with an equestrian staging area developed at Juhan Park on west bank.

Tres Rios del Norte (Reaches 4 and 5)

The proposed Tres Rios del Norte project extends from Reach 4 into Reach 5 and includes the following. • 1.25 miles of river trail on the west bank from Sweetwater Drive to El Camino del

Cerro. This trail would connect with 2 other trails: #26 Roger Wash and #27 Sweet Water Wash. Both would ultimately connect to the Saguaro National Park.

• 1.75 miles of river path on the east bank and 1.5 miles of river trail on the west bank from El Camino del Cerro to Rillito River Confluence. The west bank trail would connect to EPCTSMP #152 (no name). The east bank river path would connect with the Rillito River path.

• 1 mile of river trail on the west bank at Rillito River and Canada del Oro confluence. This trail would connect to EPCTSMP # 137 – South Branch of East Idle Hour Wash with an ultimate connection to the Saguaro National Park.

• 2.75 miles of river path/trail on the east bank and river trail on west bank between CDO confluence and Cortaro Road, with the west bank river trail connecting to # 145-Yuma Mine Trail (and ultimately toSaguaro National Park), and #146-Belmont Road. The east bank path/trail would connect to the #152-Hardy Wash Trail.

Upland Recreation Concept that connects trails, washes, and mountain parks, with river features. This feature applies to all reaches but has the biggest effect on Reaches 5 and 6.

Reach 5

• 3.75 miles of river path on both banks from Cortaro Road to Lambert Lane

alignment. West side path connects with EPCTSMP #25-Picture Rocks Wash, which ultimately connects to Saguaro National Park.

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Appendix C3 - C3-7 August 2001 Recreation Assessment

• 7 miles of river trail on both banks from the Lambert Lane alignment to Sanders Road. Both sides connect with EPCTSMP #16-Avra Valley Road and #3 Central Arizona Project Canal. The northeast bank side of the CAP trail connects to Tortilla Mountain Park.

Reach 6

• 3 miles of river trail on northeast bank from Sanders Road to Trico Marana Road and 8.5 miles of river trail on southwest bank from Sanders Road to Pinal County line.

RECREATIONAL DEMAND & BENEFITS

Benefits from recreation opportunities created by a project are measured in terms of willingness to pay. Benefits for projects (or project features) that increase supply are measured as the willingness to pay for each increment of supply. Benefits for projects (or project features) that alter willingness to pay (e.g., through quality changes) are measured as the difference between the without and with project willingness to pay. Willingness to pay includes entry and use fees actually paid for site use plus any unpaid value (surplus) enjoyed by consumers. The total willingness to pay is represented as the area under the demand curve between the old and new supply. Because most recreation is publicly provided, it is usually not possible to estimate demand directly from observed price-consumption data. An acceptable procedure for the measurement of willingness to pay, as outlined in ER 1105-2-100 (USACE, 2000), is the Unit Day Value method. The unit day value (UDV) method relies on expert or informed opinion and judgment to estimate the average willingness to pay of recreational users. By applying a carefully thought-out and adjusted unit day value to estimated use, an approximation is obtained that may be used as an estimate of project recreation benefits. The use of the unit day value method is, however, constrained by specific conditions. First, total or gross expected use of project facilities, including transfers of use from other sites shall not exceed 750,000 annual visits. Second, the general principle for the recreational analysis is, the more important recreation benefits are in plan formulation and/or plan selection and the more costly recreation components are, the more important is an economically sound and empirically defensible analysis. The arguments for employing the user day approach can be based on two foundations:

(a) Infeasibility for technical reasons or due to study cost considerations;

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Appendix C3 - C3-8 August 2001 Recreation Assessment

(b) Formulation or plan selection not materially affected by willingness to pay value or by expected visitation.

The use of the UDV method is not prohibited for this analysis, given the constraints listed above. First, no recreational element previously listed is anticipated to draw annual visitation in excess of 750,000. Second, the cost and technical requirement necessary to individually isolate each proposed recreational component, given the large number of potential individual project combinations, is beyond normal project study scopes; especially, since plan formulation or plan selection would not be materially affected by either the estimates of willingness to pay or expected visitation.

Recreational Demand

ER 1105-2-100 lists methods of estimating recreational demand either through regional use estimating models or site-specific use estimating models. The preferred site-specific method of estimating use is a use-estimating model (UEM) that relates use per 1,000 of origin population to distance traveled, socioeconomic factors, and characteristics of the site and alternative recreation opportunities. However, if a UEM is not available and cannot be estimated because of data limitations, use may be estimated by the similar project method. This method assumes that recreation demand for a proposed project can be estimated from observations of visitation patterns at one or more existing projects with similar resources, operations, and use characteristics. As an UEM is not available and existing data does not provide the resources necessary to develop such a model, this analysis will employ the similar project method. The Corps of Engineers, on the Rillito River Project, has estimated recreational use for multi-purpose trails. Additionally, Corps studies of San Timoteo and Las Vegas have also analyzed the recreational demands for multi-purpose trails. These Corps studies will serve as the basis for the estimation of annual use at the proposed recreation facilities of this analysis.

Park Demand

Annual gross per capita park visitation for the proposed parks is estimated at 0.9724, based on the above Corps studies. Adjusting this figure to exclude transfers decreases the annual per capita park visitation to 0.7692. The U.S. Census Department projects the Tucson Metropolitan Standard Area as having a population of 803,618, as of 7/1/1999. Annual visitation, therefore, at the two parks proposed in Reach 4 is,

Table 1 - Park Demand 1999

Population Mean Visitation Total

Demand 803,618 * .7692 = 618,143

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Appendix C3 - C3-9 August 2001 Recreation Assessment

Annual carrying capacity of parks has been previously estimated at 17,667 per acre. The two proposed parks have stated sizes of 6 and 50 acres. Given the calculated demand, the smaller park, the 6-acre downtown gateway water feature, would be capacity constrained at a level of 106,000 visitations. The 50-acre Irvington to Ajo Way Park has a carrying capacity of 883,350, and is not constrained.

Multi-Purpose Trail Demand

Based on the previous studies, the adjusted annual per capita multi-purpose trail use is 1.41. The estimated level of participation is 1,133,100, based on the Census data. Annual carrying capacities vary among the proposed levels of trail developments. River Park multi-purpose trails are estimated to have an annual capacity of 27,875 per linear mile. A River Path multi-purpose trail is estimated to have an annual capacity of 22,300 per linear mile, and River Trails have an estimated capacity of 9,760. The proposed multi-purpose trails have estimated carrying capacities of:

Table 2 - Multi-Purpose Trail Capacities Type Proposed Miles Capacity Factor Total Capacity

River Park 6.0 27,875 167,250

River Path 15.5 22,300 345,650

River Trail 53.0 9,760 517,280

Total 74.5 1,030,180 As the above data indicates, demand would exceed the capacity of the proposed trails. In the following analysis of benefits, a uniform reduction is assumed for all levels of multi-purpose trails.

Park Benefits

Park benefits were computed for the two parks identified under the Paseo/Rio Nuevo/Multiple Benefit concept for Reach 4 using the Unit Day Values (UDV) method. UDVs were calculated using values assigned to recreation criteria in Tables 6-29 and 6-30 of ER 1105-2-100. Specific values were selected as shown in Table 3 below.

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Appendix C3 - C3-10 August 2001 Recreation Assessment

Table 3 - Unit Day Values: Parks

Criteria Points Judgement Factors

A. Recreation Experience 12 out of 30 Moderate use, some evidence of other users and occasional interference with use due to crowding

B. Availability of Opportunity 8 out of 18 Limited opportunities within short distance

C. Carrying Capacity 11 out of 14 Optimum facilities to conduct activity at site potential

D. Accessibility 17 out of 18 Good access. High standard road to site

E. Environmental 15 out of 20 High aesthetic quality

Total:

63 out of 100 = user day

dollar value of $6.39

General Recreation

Based on a unit day value of $6.39 per visit, the annual benefits derived from the two proposed parks are:

• 6-acre downtown gateway water feature 106,000 * $6.39 = $677,340

• 50-acre Irvington to Ajo Way Park

618,143 * $6.39 = $3,949,934 Total park benefits to Reach 4 total $4,627,274.

Multi-Purpose Trail Benefits

Applying the UDV method outlined in ER 1105-2-100 yields the following judgments on multi-purpose trails.

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Appendix C3 - C3-11 August 2001 Recreation Assessment

Table 4 - Unit Day Values: Multi-Purpose Trails

River Park & River Path River Trail Criteria

Points Judgement Factors Points Judgement Factors

A. Recreation Experience 10 out of 30

Walking, Jogging, Rollerblading, Biking;

interpretive activities such as bird watching

20 out of 30 Usually little evidence of other users, rarely if ever

crowded

B. Availability of Opportunity 8 out of 18 Limited opportunities within

short distance 3 out of 18 Several within 1 hr. travel time

C. Carrying Capacity 8 out of 14 Facilities will adequately

support required usage 2 out of 14 Minimum facility

development for public health and safety

D. Accessibility 16 out of 18 Good access, high standard road to site 11 out of 18 Good access, good roads

to site

E. Environmental 15 out of 20 High aesthetic quality 3 out of 20 Average aesthetic quality

Totals: 57 out of 100 = user day dollar value of $6.14

General Recreation 39 out of 100 = user day dollar value of $5.00

General Recreation

Annual benefits by proposed multi-purpose trail feature, based on unit day values of $6.14 for River Park and River Path multi-purpose trails and $5.00 for River Trail multi-purpose trails and assuming a proportional use based on trail miles, are as follows.

Table 5 – Multi-Purpose Trail Values Feature/Area Type Miles Attendance Value

Flood prone land acquisition (Reaches 1 and 2) Trail 20.0 195,200 $1,089,664

Trail 1.0 9,760 $54,483

Path 4.0 89,200 $405,490 Paseo/Rio Nuevo/Multiple Benefit projects (Reach 4)

Park 3.0 83,625 $466,820

Grant to Fort Lowell (Reach 4) Park 3.0 83,625 $466,820

Tres Rios area (Reaches 4 and 5) Trail 6.5 63,440 $354,141

Path 4.0 89,200 $405,490

Upland Recreation Concept (Reaches 5 and 6) Trail 25.5 248,880 $760,293

Path 7.5 167,250 $1,389,323

Total 74.5 1,030,180 $5,392,524

Total Annual Recreational Benefits

If the proposed recreational facilities are constructed, total annual recreational benefits from these facilities are estimated as follows.

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Appendix C3 - C3-12 August 2001 Recreation Assessment

Table 6 – Total Annual Recreational Benefits Type Annual Benefits

Parks: Downtown Gateway Park $677,340 Irvington to Ajo Way Park $3,949,934 Multi-Purpose Trails: Flood prone land acquisition (Reaches 1 and 2) $1,089,664 Paseo/Rio Nuevo/Multiple Benefit projects (Reach 4) $926,793 Grant to Fort Lowell (Reach 4) $466,820 Tres Rios area (Reaches 4 and 5) $759,631 Upland Recreation Concept (Reaches 5 and 6) $2,149,616

Total $10,019,798