Impact/Purpose:

Develop sampling protocols and a comprehensive database to field test developmental, predictive TMDL models. These protocols and models will then be applied for calculating TMDLs.

Description:

Recent trends in current and evolving environmental regulatory strategies dictate that EPA will have to rely more heavily on predictive modeling technologies in carrying-out the increasingly complex array of exposure and risk assessments necessary to develop scientifically defensible regulations (GPRA Goal 8.1.1). Under 303(d) of the CWA, each State must produce and provide EPA with a list of waters where water quality standards are not being attained, prioritize the development of Total Maximum Daily Loads (TMDLs) for the waterbodies that will result in attainment of the standards, and then develop and implement the TMDLs. In the event a State fails to develop the list or to develop TMDLs, EPA is obligated to do so. A TMDL is an estimate of the maximum pollutant loading both from point and nonpoint sources that receiving waters can accept without exceeding water quality standards. EPA's Office of Research and Development, National Exposure Research Laboratory, Ecosystems Research Division (ERD) in Athens, GA, together with the Agency's Region 4 Science and Ecosystem Support and Water Management Divisions, designed and developed a sampling plan for a field research study in the South Fork Broad River (SFBR) of the Broad River Watershed located in the Savannah River Basin. In 1998, the State of Georgia listed the South Fork Broad River Watershed as biologically impaired, but the source of contamination was unknown. This study involves the collection of storm event samples at six instrumented stream sites for the analysis of bedload and suspended sediment, nutrients (nitrate, ammonia, total nitrogen, phosphorus), organic carbon and pathogens (fecal coliforms, E. coli, and enterococci). There is a pressing need in the Agency for a comprehensive data set for use in developing sampling protocols and predictive pollutant loading and fate and transport models, and to field test these models with actual field data.

Record Details:

Record Type:PROJECT

Start Date:10/01/2001

Completion Date:09/30/2004

OMB Category:Other

Record ID: 56092

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Project Information:

Progress :Six stream sites have been instrumented with specialized monitoring equipment (ISCO automatic samplers, YSI multi-probes, and 3-sites with cableway systems) for collecting data before, during and after storm events, measuring depth, turbidity, specific conductance, pH, DO, ORP, and temperature. About three hundred stream cross-sectional sites have been located, surveyed and sampling/analysis is ongoing for stream bed characterization. About 90 stream cross-sectional sites have been sampled, and analysis completed for stream bed characterization. Extensive background data have been collected for the SFBR watershed. Rain events tracked and sampled through 2002 have not produced extensive run-off and sediment loads due to the project area being in its fourth year of a severe drought condition, with stream levels at their lowest in many years. Sampling teams have been formed to conduct the rain-event field study in the SFBR watershed, most of the necessary equipment has been purchased, and all supporting extramural vehicles have been implemented or developed for implementation: e.g., an IAG with USGS to develop stage-discharge rating curves at the six ERD sampling stations in the SFBR and at a real-time station at the watershed outlet; an IAG with the US Army Corps of Engineers for database development; and a task order under EPA Region 4 contract to survey stream cross-sections, develop elevations at these cross-sectional stream sites using bridge benchmarks, and to provide the necessary staff to collect bedload, depth integrated and pathogen samples during storm events at four high priority stream sites in the SFBR watershed.

More rainfall (number of events and the amount) occurred during 2003 than any other year since the beginning of the field research project. A large rain event was predicted to occur during early April 2003 that produced a week of sampling 4-days of intensive sampling. This rain event was not as intensive as expected relative to producing heavy run-off but did produce a low intensity rain over several days. Unfortunately, during this sampling event, two sites with Rickly Hydrological Company cableway systems malfunctioned, became inoperable and unsafe, and, therefore, eliminated further rain event sampling until replacement winches could be installed. After many discussions with the Rickly Company president, the company finally agreed to replace both winch systems (without additional cost) the week of November 17th, 2003. The cableway system problems has caused unexpected delays in obtaining the required data during a period of greater rainfall. Current funding for the contract field sampling support during rain events is sufficient for only two additional sampling days.

The focus of the stream cross-sectional sampling plan has been changed to assess the contribution of stream channel bed and stream bank erosion to in-stream sediment loads at 24 stream cross-sections (4-sites above each of the six primary stream sampling sties) with repeated sampling after high rainfall events. At each stream cross section, stream profile and ground photographs are taken, and samples collected from stream bed, bank and floodplain areas. Repeated sampling at these sites after large rain events will be conducted to identify areas where serious stream cross-section changes are occurring, and to develop relationships between watershed characteristics and changes in stream channel cross-section profiles. The repeated measures will indicate the rate of sediment deposition or sediment erosion that is occurring on the stream channel bed and channel banks at each cross-section. Within each stream cross-section, particle size distribution of sediments collected from stream bottom areas will be compared to sediments collected from channel banks and the surface horizon of the adjacent floodplain.

Relevance :TMDL research is an important component of emerging multimedia modeling technology required to carry-out the increasingly complex array of exposure and risk assessments necessary to develop scientifically defensible regulations (TMDL, GPRA Goal 8..1.1). This program will directly support the mandates under the Clean Water Act, section 303.(d).

Clients :Region 4 (Jim Greenfield, Bill Bokey)

Project IDs:

ID Code :12556

Project type :OMIS