WATER QUALITY TRENDS IN THE ROUGE RIVER WATERSHED
Abstract:The Rouge River basin is an urban/suburban watershed of 48 communities that drains 466 square miles of southeastern Michigan and discharges into the Detroit River. The Rouge suffers from typical urban watershed stressors including discharges from combined sewer overflows (CSOs), sanitary sewer overflows (SSOs), non-point sources, limited industrial discharges, contaminated sediments and high flow variability. These factors have resulted in public health advisories for fish consumption and water recreation, poor biotic communities, impoundment eutrophication, and damage to the stream channel morphology.
The Rouge River National Wet Weather Demonstration Project (Rouge Project), funded by the United States Environmental Protection Agency (USEPA) through Wayne County's Department of Environment, was initiated in 1992 to address these impairments. The project implemented an intensive monitoring program to assess existing conditions, identify primary pollution sources, and track long-term trends. Components of the program include continuous monitoring of dissolved oxygen (DO), water temperature, stream flow, and rainfall; intermittent dry and wet weather water quality sampling; and periodic assessments of the trophic status of major impoundments, stream geomorphology, sediment quality, and macro-invertebrate populations. After ten years, the sampling program has generated over 15 million records of data.
Sampling conducted during the first few years of the project showed that E. coli bacteria concentrations were well above the Michigan Department of Environmental Quality (MDEQ) water quality standards for both full and partial body contact recreation. DO deficiencies were prevalent particularly downstream of CSO areas and in river reaches with low stream flow. Nutrient concentrations were high particularly in impoundments, and one of the impoundments was contaminated by Poly-chlorinated biphenyls (PCBs). The Rouge Project implemented several watershed management activities to address these concerns, including construction of ten CSO retention treatment basins, sewer separation in six communities, participation of all 48 communities in a watershed-wide storm water management permit program, and several local remediation projects including the dredging of the PCB-contaminated impoundment, reconnection of an oxbow to a channelized portion of the river, and community illicit discharge detection programs.
To evaluate the effectiveness of watershed management activities, DO and E. coli bacteria data collected from 1994 to 2002 were assessed using two different trend analysis techniques, linear regression and Seasonal Kendall analysis. At all locations with representative data substantial improvements in DO have been observed during both wet and dry weather conditions. In 2002, seven of the eight continuously monitored DO locations met the State DO standard more than 80 percent of the time.
E. coli bacteria concentrations are also improving, particularly downstream of now controlled CSO outfalls. However, most locations are still not meeting State water quality standards and a number of locations in the headwaters and downstream of still uncontrolled CSO outfalls are showing potentially degrading trends. Although these results clearly demonstrate that implemented watershed management activities have been successful, it is evident that continued diligence in addressing remaining water quality pollution sources is necessary and should lead to continued improvement.
Document Type: Research Article
Publication date: January 1, 2004
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