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A look at the trends for water resources in teh Coon Creek watershed in Anoka County, MN. This is part of our 10-year planning process.
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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