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...
In 1999, the Detroit Water and Sewerage Department (DWSD) implemented a Detroit River water quality monitoring program to establish a basis for determining the effectiveness of three pilot combined sewer overflow (CSO) facilities and to help define what other CSO controls should be undertaken as part of the Long Term CSO Control Plan. In addition to protecting public health and eliminating raw sewage, a major concern of the Michigan Department of Environmental Quality (MDEQ) was whether CSOs along the Detroit River are causing a depression of the dissolved oxygen (DO) in the river to below the state's cold water fishery standard of 7 milligrams per liter (mg/l) (MDEQ 1994).The key issues identified by the Long-Term CSO Control Plan's Water Quality Work Group (WQWG) that this paper focuses on are: § The presence and extent of dissolved oxygen (DO) levels that are below the cold water fisheries standard and that can be attributed to upstream CSOs on the Detroit River. § The extent of aesthetic impairments, if any, directly resulting from CSOs. § The extent of other use impairments, if any, directly resulting from CSOs (recreational water contact, water supply, etc.). § The ecological impacts of untreated and treated CSO discharges on aquatic communities, especially benthic macroinvertebrates. § The extent of the CSO discharge plumes.Specific water quality monitoring and survey activities were developed and have been implemented to investigate these issues. The collection of water quality data began several years before construction of the first pilot CSO control facility was completed, and will continue until 2 years after the third pilot facility is completed.The monitoring performed since 1999 has shown DWSD's CSO discharges are not causing DO in the Detroit River to fall below the standard, indicating that future controls for Detroit River CSOs may not need to be designed to reduce suspended solids and biochemical oxygen demand. This could allow the use of screening and disinfection facilities instead of retention treatment basins, resulting in considerable capital, as well as O&M cost savings and using much less of the valuable shoreline property. Collecting water quality data before the construction of these pilot facilities has provided the opportunity to demonstrate whether the receiving water's baseline conditions and capacity for assimilating oxygen-demanding material require the additional capture that CSO basins provide. DWSD will need to gain the acceptance of MDEQ for future proposed levels of CSO control and treatment technologies.
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