Many people do not realize that there are two separate sewer systems running underneath Ashland Streets – sanitary sewer and storm sewer. The sanitary system collects human wastewater from toilets, sinks, baths and showers and delivers it to the city’s wastewater plant for treatment. The storm system collects precipitation and delivers it to streams, usually without any treatment at all.
The inlets you see along curbs and the catchbasins you see in parking lots DO NOT send water to a treatment plant. Their primary purpose is to capture rainwater runoff to alleviate flooding, and they generally discharge stormwater directly into the nearest stream. This runoff may be carrying pollutants including mud, fertilizer, pet waste, trash and a variety of substances generated by vehicles including asbestos, rubber, oil, brake and power steering fluid and antifreeze. In summer, stormwater flowing off hot pavement causes thermal pollution by increasing stream temperatures that may already be dangerously warm for native coldwater species, especially salmon and trout. Stormwater is referred to as “non-point source” pollution, because it comes from “everywhere”, instead of out of a single pipe like pollution from an industrial plant.
The Clean Water Act of 1972 has been successful in limiting point source pollution in the US. However, over the past few decades it has become evident that - as point sources are eliminated or cleaned up - non-point source pollution has become a larger part of the remaining problem. Although harder to regulate, both the federal Environmental Protection Agency and the state Department of Environmental Quality exercise control over stormwater, primarily through the Total Maximum Daily Load (TMDL) program and the National Pollution Discharge Elimination System Phase II Stormwater Program. City of Ashland is regulated by both programs, and is an active participant in regional efforts to meet compliance standards. For more information about the TMDL and Phase II programs, please explore the following links.
NPDES Phase II program: