This document discusses linking water quality at Great Lakes beaches to land use in the surrounding watershed. It presents initial models that relate levels of E. coli bacteria at a beach in Racine, WI to rainfall, river discharge levels, and estimated bacterial loads from the nearby Root River watershed. The models explain around 40% of the variation in bacteria levels and include factors like wave height, water clarity, and seasonal effects. Future work is aimed at refining the watershed loading estimates and validating the linked beach-watershed modeling framework.
Stormwater regulations and their relationship to tmd ls
Linking Great Lakes Beach Water Quality to Land Use
1. Linking Great Lakes Beach Water-
Quality to Land Use
Adam C. Mednick
Wisconsin Dept. of Natural Resources
WAFSCM Conference, 11/4/10, Wisconsin Dells
2. Outline
I. Problem/ Background
II. Beach Water-Quality “Nowcasts”
III. From Beach to Watershed
IV. Modeling/ Decision-Support Framework
3. I. The Problem
Elevated fecal indicator bacteria
in nearshore recreational waters
Public health impacts
Escherichia coli
Economic impacts
In WI 2003-2009:
3,737 Swim Advisories
912 Beach Closures
4. Difficult to ID/ Mitigate Sources
Sources, pathways, and contributing
factors vary from beach to beach
Source: NOAA GLERL
5. Monitoring Challenges
Standard methods take 18-24 hours
Collect/ transport water quality samples
Lab analysis
Quanti-tray enumeration
6. Monitoring Errors (Type I) .
Wisconsin 2003-2009:
63% of closings reflected false exceedances
of state closure guideline (1,000 CFU/100 mL)
42% of advisories reflected false
exceedances of the EPA freshwater standard
(235 CFU/ 100 mL)
7. Monitoring Errors (Type II)
Wisconsin 2003-2009:
3% of non-advisory days with water quality
samples exceeded the state guideline
(1,000 CFU); i.e. should have been closed
9%… exceeded the EPA standard (235 CFU);
i.e., should have been posted
14. X6 = Nearshore Current
Grand River Plume (4/20/10)
Grand Haven State Park, Michigan
Source: NOAA GLERL
15. X6 = Nearshore Current
Grand River Plume (4/20/10)
Grand Haven State Park, Michigan
Source: NOAA GLERL
16. X6 = Nearshore Current
Grand River Plume (4/20/10)
Grand Haven State Park, Michigan
Source: NOAA GLERL
17. X7 = FIB loading
Grand River Plume (4/20/10)
Grand Haven State Park, Michigan
Source: NOAA GLERL
18. First Operational “Nowcast” in WI
Port Washington, 2009-2010
Explanatory Variables:
48-hour Rainfall
Turbidity (NTU)
24-hr Stream Flow (total discharge)
Wave Height
Water Temperature
Air Temperature
“Third Qtr” of Beach Season (Y/N)
20. First Operational “Nowcast” in WI
Sample date/time E. Coli E. Coli Units
(Model) (Lab)
Tues. 7/13/2010 8:30 4 23 MPN/ 100ml
Wed. 7/14/2010 8:30 24 24 MPN/ 100ml
Thurs. 7/15/2010 9:00 3,432 2,419 MPN/ 100ml
Friday 7/16/2010 8:50 166 127 MPN/ 100ml
21. Expanded “Nowcast” Modeling
Federal Great Lakes
Restoration Initiative
From 1 operational
nowcast to 20 by 2013
59 candidate beaches Pt. Washington
Adequate data
Study Area
High-priority and/or
impaired
23. Root River, Racine
Beach/Waterfront economically important
Veryhigh number of closures and swim
advisories prior to 2006
Inter-agency effort to address problem:
City Public Health Dept., Engineering Dept.,
Planning Dept.
26. Watershed Conditions
Post-mitigation,
contamination events
primarily associated with major storm
events/ Root River discharge
Riverplumes often
associated with
elevated FIB at Great
Lakes beaches, as well
as Marine beaches
(e.g. He & He 2008) Grand River at Grand Haven, MI
Source: NOAA
30. Samples vs. Flow Conditions
Flow Duration Curve (daily data 1963-2009)
Wet Conditions Dry Conditions
10000
All Dates 1962-2009
1000 Sample Dates (N~75)
Log of flow (cfs)
100
10
1
0 10 20 30 40 50 60 70 80 90 100
0.1
0.01
Percent of time flow rate exceeded
31. Applied-Research Questions
Can we develop a modeling framework
that links nearshore FIB concentrations to
watershed conditions?
Land Use
Development Practices (LID)
Ifso, can we translate this into a usable
Planning-Support Tool?
Nowcasts for Public Health officials
Impact Assessment for Planners
32. Limited Research to date
Kay and colleagues (2005) modeled real-
time FIB fluxes for a coastal watershed
discharging near recreational waters on
the Irish Sea.
Export coefficients based on percentages
of different land uses
Did
not link outputs to nearshore FIB
concentrations
33. IV. Modeling/ Decision-Support
Framework
Watershed modeling component
Rainfall
Beach “nowcast” component
Land Use Soils
Rainfall Waves Wind Turbidity Current
Runoff
NPS Nearshore
E. coli E. coli
34. Watershed Component
Based on Long-Term Hydrologic Impact
Assessment (“L-THIA”)
Spatially-distributed automation of rainfall-runoff
Curve Number (CN) method + event mean
concentration (EMC) coefficients
Simple model
Similar to PLOAD
Basis for runoff/NPS in the PSS software “INDEX”
Enables Web application
37. Beach Component
U.S.
EPA’s “Virtual Beach”:
Model-building/ decision-support tool
Walks beach managers through the
process of building
and operating
statistical models to
predict real-time FIB
concentrations
38. Initial Watershed Models
Distributed
CN’s based on 30m land use
(NLCD 2001) and soils (SSURGO)
Daily rainfall (2007-10) from Racine Airport
CN’sadjusted for Antecedent Soil
Moisture based on previous 5 days
Daily direct runoff estimates per 30m cell
39. Root River
Watershed
2010 Land Use (NLCD)
Open Water
Developed, Open Space
Developed, Low Intensity
Developed, Medium Intensit
Developed, High Intensity
Barren Land
Deciduous Forest
Evergreen Forest
Mixed Forest
Shrub/Scrub
Grassland/Herbaceous
Pasture/Hay
Cultivated Crops
Woody Wetlands
Emergent Wetlands
0 5 Kilometers
43. E. coli Coefficients
For each land use, 4 different sets of
EMC coefficients for total coliforms,
adjusted (EC = 0.625 * TC):
1. L-THIA default EMCs
2. WMM EMCs (Rouge River Natl. Wet
Weather Demonstration Project 1998)
3. PLOAD EMCs (U.S. EPA 2001)
4. NSQD median values (Pitt el al. 2009)
47. Forthcoming
Watershed-specificEMC coefficients
estimated Root River data
Data partitioned by flow regime and season
Substitute lot-level land use for NLCD
Calibrate curve numbers
Validate E. coli estimates against sampling
LID-adjusted curve numbers
48. Linking Great Lakes Beach Water-
Quality to Land Use
Adam C. Mednick
Wisconsin Dept. of Natural Resources
WAFSCM Conference, 11/4/10, Wisconsin Dells