7 14-2010 cp resource assessment

Coon Creek Watershed District

Water Resource Assessment &

IssuesJuly 14, 2010

Agenda (7/14/10)

1. Introductions

2. Review from 3/30/10 Meeting3. Review of Stated Issues & Concerns

4. Changes in Resource Conditions5. Demands for Resource Uses

6. Water Management Issues

3/30 Meeting ReviewApproach & Process

2010 2011

Q1 Q2 Q3 Q4 Q1Review Requirements & Issues

*

Resource Trends & Implications

- *

Issues & Concerns *Implementation:

Goals & Measures*

Agency Review *

Local Agency AttendanceInvites 3/30 7/14

ACD * *

Anoka County * *

Andover * *

Blaine * *

Columbus

Coon Rapids *

CLAA * *

Ham Lake * *

State Agency AttendanceInvites 3/30 7/14

BWSR * *

DNR * *

Met Council * *

PCA * *

DOT -

DA-agriculture

DH -health

March Meetings

3. Review of Stated Issues & Concerns

CCWD Board Issues & Concerns 3/8/10

Issue ConcernEnforcement Effective and quick

enforcement

Getting ahead of increasing water quality concerns

Water quantity vs. quality conflicts

Working through with State Agencies

Groundwater-Surface Water Connection

Many physical resource needs may be beyond our control

Planning Advisory Group Issues & Concerns 3/30/10

1. Water Quality- TMDLs: City Involvement

2. Lake Management Plans for other lakes

3. Earth Friendly Ditch Management – Multiple Use

4. Buffer Strips

5. Infiltration - groundwater effect

6. Credit for ponds that infiltrate

7. Coordination of monitoring for state/other permit reports

8. Wetland Functions & Values assessment

9. Document collaboration with I&E efforts

10. Document District Retrofit efforts

11. Effect of Mining/dewatering on wetlands – subwatershed

12. Groundwater Modeling standards

BWSR Initial Issues & Concerns

Issue/Concern NotesStatus of Progress –

What has been completed?

Public Involvement Process City environmental committees,

Neighborhood Assoc.

O&M & Capital Prioritization

General Schedule

For use in grant applications

Detailed Water Monitoring Program

Include budget; key water bodies, party collecting data; type of data collected; Trends

Goals & Objectives Reasonable & Measurable

MPCA Initial Issues & Concerns

1. LID/MID Principles 6. Wetland Regs. consistent w/ MR 7050

2. Impaired waters goals 7. Monitoring Program

3. Stormwater runoff goals and standards

4. Implementation schedule & responsibilities

5. Wetland Functions & Values

Summary18 issues raised:

7 Physical Resources

11 Managerial/Compliance

Physical Resource IssuesGroundwater Groundwater x Surface water

Effects of dewatering

Effect of infiltration on GW Quality

Lakes Comprehensive Plans

Water Quality Quality vs Quantity tradeoffs

General Water Quality

Wetlands Functional Assessment

Managerial IssuesPerformance & Document Measures

Goals & Objectives

Schedule

Involvement/Coordination Comp Plan, TMDL

Modeling Standard approach

Enforcement & Regulation Coordination

Principles (LID/MID &7050)

Credits

Policy & Planning Naturalized Ditch Design

Values Benefits & Priorities

Online: www.cooncreekwd.org

ReviewsCurrent Plan2000-2009 Changes & TrendsImplications of Changes & Trends2020 Management Expectations

4. Changes in Resource Conditions

PrecipitationLess annual precipitation

Greater occurrence of larger events over smaller areas

Annual Precipitation (Last Decade)

y = -0.4053x + 33.5350.00

5.00

10.00

15.00

20.00

25.00

30.00

35.00

40.00

45.00

1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009

Pre

cip

(in

.)

Annual (Last decade) Linear (Annual (Last decade))

CCWD 2010

PrecipitationFrequency of occurrence remains the same

Rainfall Frequency Spectrum

0

0.5

1

1.5

2

2.5

3

3.5

4

4.5

5

0 10 20 30 40 50 60 70 80 90 95 100

Percentile (%)

Rai

nfa

ll D

epth

(in

ches

)

CCWD 2010

EvapotranspirationLess Excess Precipitation

= Less Natural RechargeThornthwaite

y = -0.5259x + 9.0047

-2

0

2

4

6

8

10

12

14

16

18

2000 2001 2002 2003 2004 2005 2006 2007 2008 2009

Year

Exc

ess

Pre

cip

(in

)

Yearly Thornthwaite Excess Period of Record AvgLinear (Yearly Thornthwaite Excess)

CCWD 2010

Surficial Groundwater LandscapesRiver Terrace Lake Deposits

Generalized Profile(Upper 120 ft)

800

810

820

830

840

850

860

870

880

890

900

910

920

Round

Lk Bld

Hanso

n

Univer

sity

Centra

l

Lexin

gton

MPCA 1997

River Terrace Lake Deposits

Water Table

Sand

Clay

Direction of Flow

Surficial Groundwater Used Elevation change 1978 to 2008

CCWD 2010

Surficial Groundwater

1.Effective ground watershed is slightly larger than surface watershed

2.Less groundwater available

3.More difficult to maintain surface water resources driven by groundwater

4.More differentiation across the watershed

Surface Water

Ponding/ Rate control is working

Flashy lower portion of the watershed remains (Coon Rapids)

Montgomery-Watson 1999Wenck & Assoc 2009

Lakes

Declines in water levels in Lakes and wetlands

Water quality has significantly improved from 1983 to 2009Secchi transparency has an improving trend since 1993 Total phosphorus and chlorophyll-a are statistically unchanged

ACD 2009Met Council 2009

Crooked Lake

859.0

860.0

861.0

862.0

863.0

1/1/

05

7/1/

05

1/1/

06

7/1/

06

1/1/

07

7/1/

07

1/1/

08

7/1/

08

1/1/

09

7/1/

09

1/1/

10

Ele

va

tio

n (

ft)

OHW = 862.1

Water QualityImpaired for Biota TMDL=(TSS + DO)

Exceeding standards for Turbidity

Total Suspended Solids

Phosphorus

Lower (older) portion of the watershed lacks infrastructure needed for water quality

ACD 2009

WetlandsProbable loss of 52% of wetland stock

Met Council 2009

WildlifeNeed to model Habitat needs for critical natural elements (E,T, & SC species &

communities)Fishery potentially stressed with lower lake levels

Native Vegetation

5a. Direct DemandsPeople

LandTransportationMining

DrainageAgricultureDewatering

WaterIrrigationAesthetics

Population Trends2010 2020 Change

Andover 24,048 27,006 12%

Blaine 39,597 50,987 29%

Columbus 508 623 23%

Coon Rapids 44,479 44,005 -1%

Ham Lake 15,017 16,686 11%

Total 123,649 139,307 12%

Change 22% 13% 13%

1.3% average annual growth

Land

7,500 acre decrease in agricultural land

Estimated 7,800 acre increase in impervious surface - mostly in headwaters

DrainageDemand decreases

Water – Surficial AquiferEstimated 2.8 BGY average over last 22 years

0.0

200.0

400.0

600.0

800.0

1000.0

1200.0

2004 2005 2006 2007 2008

Year

MG

Y

Nursery

Agriculture

Landscaping

Golf Course

Ditches and groundwater could become an increasing source of water for commercial uses

Transportation

More aggressive winter maintenance (salt & sand = Chlorides & TSS)

More impervious area

Mining/Dewatering

Decrease in Groundwater Supplies

Changes in Wetlands, Trees and Parks

Land Subsidence

Recreation

Increased interest in navigation of the Creek

Increased evaluation of ditch corridors for trail purposes

Public Land

19.7% of land tax exempt

Contribution to loadings and associated costs becomes an issue

Increased need for SWPPPs/SAMPs

Flood Control

Groundwater Recharge

Water Quality

5b. Indirect Demands

Flood ControlMore “localized” Regional flood events

Storms outside the “normal” distributionHigher HighsLower Lows

Groundwater Recharge

Only way to influence surficial groundwater

Need 15 to 20,000 AFPY for 10 Years to return to 1988 elevations (CCWD)

Water Quality & Stormwater

Parameter Action Factor

Turbidity Reduce 3

TSS Reduce 8

Phosphorus Reduce 2.5

Dissolved Oxygen Maintain

Volume Maintain

Biota Develop TMDL

7. Water Management Issues

Temporal IssuesThinking about the next 10 years

Precipitation30” per yr

+ 2”

Continue to Decline< 28” per yr

(40%)

Return to Normal30” +2(40%)

Increase>33” per yr

(20%)

Get Drier Stays Dry Gets Wet

Key IssuesIssue Need

Water Quality Volume Retain some of the load by capturing amount or volume

Groundwater Recharge Infiltrate to predevelopment Soil Hydro group

Channel Protection Reduce erosive velocities & unstable conditions

Overbank Flood Protection Control post development peak to predevelopment rate

Extreme Storm Evaluate 100 yr event

Rainfall Frequency Spectrum

0

0.5

1

1.5

2

2.5

3

3.5

4

4.5

5

0 10 20 30 40 50 60 70 80 90 95 100

Percentile (%)

Rai

nfa

ll D

epth

(in

ches

)

Management Issues

Which rainfall event or runoff volume should be the basis for computing water quality volume:

Option Rainfall Amt WQ Volume90% Annual Rainfall

1.15” 2.6 ac-ft

95% Annual Rainfall

1.5” 3.4 ac-ft

Pitt Method 1.25” 3.0 ac-ft

1 Yr-24 hr Storm 2.3” 6.2 ac-ft

Obvious Issues & ConcernsFrom Resource Assessment

Obvious Issues Supply & Capacity

Thornthwaite

y = -0.5259x + 9.0047

-2

0

2

4

6

8

10

12

14

16

18

2000 2001 2002 2003 2004 2005 2006 2007 2008 2009

Year

Exc

ess

Pre

cip

(in

)

Yearly Thornthwaite Excess Period of Record AvgLinear (Yearly Thornthwaite Excess)

PrecipitationLess annual precipitationGreater occurrence of larger precipitation events over

smaller areasLess Excess Precipitation = Less Natural Recharge

Annual Precipitation (Last Decade)

y = -0.4053x + 33.5350.00

5.00

10.00

15.00

20.00

25.00

30.00

35.00

40.00

45.00

1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009

Pre

cip

(in

.)

Annual (Last decade) Linear (Annual (Last decade))

Obvious Issues Supply & Capacity

GroundwaterLess groundwater available

More difficult to maintain surface water resources

Lakes & WetlandsDeclines in water levels in Lakes and wetlands

Probable loss of 52% of wetlands

Obvious Issues Supply & Capacity

Surface WaterFlashy lower portion of

the watershed

Short bursts of high volume/high velocity runoff events on sandy substrates and impervious surfaces

Obvious Issues Direct-Demand & Utilization

Land7,800 acre increase in impervious surface mostly in

headwaters

Drainage7,500 acre decrease in agricultural land

Water SourceDitches and groundwater become an increasing source

of water for commercial uses

Obvious Issues Indirect Demand

Flood ControlMore “localized” Regional flood events (Andover x Ham

Lake)

Groundwater RechargeNeed approximately 15 to 20,000 AFPY for 10 Years to

return to 1988 elevations

Water QualityBiotaTurbidity, TSS, Phosphorus

Issue ChainDecline in

Precipitation

Decrease in Groundwater Recharge

Decline in Surficial Groundwater Levels

Decline in Lake levels, Wetlands

Increased Need to Irrigate

Decreased NeedTo Drain

Further Decline inGroundwater Levels

Increased Stress on Fishery & Wildlife

Decrease in Recreational Use

Increase in “dry”Marginal Land

Higher IntensityRainfall Events

Increased Volume & Rate of Runoff

Increased PotentialFor Local Flooding

Increased ErosionTSS & Turbidity

Increased Stress onFishery & Biota

More Involved Site Assessments

Increased Water Harvesting

Increased PotentialFor Local Flooding

Increase inDewatering

Increased Evaporative Loss thru Lakes