Interpreting and Using Existing Data to Identify

Pollution Causes and Sources

Confirm impairments and identify pollutants

Compare available monitoring data to wqs:• Document magnitude of impairment• Document seasonal/temporal patterns• Document spatial distribution

Spatial Analysis

• Isolate critical subwatersheds• Combine with land use/land cover data

Flow Relationships

• Point vs. Nonpoint

Flow Relationships

• Point vs. Nonpoint

Temporal Analysis

• Seasonality• Stratify data by potential source activities

– Tillage– Crop canopy development– Manure/fertilizer applications– Grazing season– Logging– Construction projects– Street cleaning

Other tools:

• Stakeholder knowledge• Direct observation (streamwalk)• Specialized tools, e.g., microbial source

tracking, ground water aging

Supplementing available data

– Windshield surveys– Interviews with residents– Volunteer monitoring– Bioassessment– Targeted sampling– Chemical/biological sampling

Helps lay the groundwork for implementation!

Examples

St. Albans Bay VT RCWP

• Known WQ impairment due to eutrophication– Obvious algae blooms & macrophyte growth– Declining State Park visits, beach closures– State DEC P monitoring

• Excessive P loads to Bay• 75% point source/25% nps

• NRCS knowledge about current status of animal waste management, milkhouse waste, cropland erosion

St. Albans Bay VT RCWP

Lake Pittsfield IL

• Lake Pittsfield is a 220 ac lake located near the city of Pittsfield in the 25,393 ac Blue Creek watershed in Pike County, western Illinois

• Constructed in 1961 as a flood control reservoir.

• Sediment deposition the dominant water quality problem

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Lake Pittsfield IL

• 1979 vegetative practices on agricultural land slowed sedimentation rate

• Lake sedimentation still higher than desired• Additional practices needed – WASCOBs and

sediment retention basins

Lake Pittsfield IL

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WASCOBs installedConstruction of 12 rock riffles (Newbury Weirs)Station D annual sediment yield (tons/acre)Station C annual sediment yield (tons/acre)Station D yield/discharge (tons/ac-ft)Station C yield/discharge (tons/ac-ft)

1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004

VT 319 NMP

04-Jan-9512-Apr-95

19-Jul-9530-Oct-95

07-Feb-9615-May-96

19-Aug-9616-Dec-96

31-Mar-9702-Jul-97

06-Oct-9721-Jan-98

29-Apr-9829-Jul-98

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E. Coli Counts 1995 - 1998Lake Champlain Basin Ag Watersheds NMP Project

VT 319 NMP

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Instantaneous Streamflow (ft3/sec)

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Streamflow and E. Coli CountsWS 2 1995 - 1998

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VT 319 NMP

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Lake Champlain Basin Ag Watersheds NMP Project

VT 319 NMP

VT 319 NMP

Identification of stressors

• Where causes of biological impairment are unknown, use characterization data to help identify stressors

Stressor Identification

Stressor Identification

Resources:• USEPA Stressor Identification Guidance Document

www.epa.gov/waterscience/biocriteria/stressors/stressors.html

• USEPA Causal Analysis/Diagnosis Decision Information System (CADDIS) http://cfpub.epa.gov/caddis/home.cfm