Washington Street West watershed - City of Champaign

Draft ReportWest Washington Street Watershed Master Planreduce stormwater pollution. Implementing this type of design in the West WashingtonStreet watershed would be consistent with recommendations in the Copper SloughWatershed Master Plan prepared for the City of Champaign, and would also help theCity demonstrate its continued compliance with its NPDES municipal stormwaterpermit.4.6 STATUS OF THE COPPER SLOUGHWater pollution control programs are designed to protect the “designated uses” of the waterresources of the state. Each state has the responsibility to set water quality standards that protectthese designated uses, which include aquatic life, wildlife, agricultural use, primary contact (e.g.swimming, water skiing), secondary contact (e.g. boating, fishing), industrial use, drinking water,food-processing water supply, and aesthetic quality.Section 303(d) of the federal Clean Water Act (CWA) requires states to identify waters that donot meet applicable water quality standards or do not fully support their designated uses. Statesare required to submit a prioritized list of impaired waters, known as the 303(d) List, to theUSEPA for review and approval.The CWA also requires that a Total Maximum Daily Load (TMDL) be developed for eachpollutant of an impaired waterbody. The establishment of a TMDL sets the pollutant reductiongoal necessary to improve impaired waters.The Copper Slough is currently not listed as a 303(d) impaired stream. There is no evidence toidentify the West Washington Street watershed as a possible source of stormwater contaminants;however, stormwater runoff in the West Washington Street watershed will contribute urbanrunoff to the Copper Slough, which typically carries known pollutants, such as nutrients (nitrogenand phosphorus), heavy metals (lead and copper) and bacteria (fecal coliform) from animal waste.The Copper Slough does not currently have TMDLs established for the downstream reach andthere is no timetable for TMDL development for this watershed. However, the IllinoisEnvironmental Protection Agency (IEPA) may choose to add the Copper Slough to their TMDLWatershed List in the future. At this time, there is no indication when (and if) that will occur.As part of the City’s NPDES municipal stormwater permit (ILR40), the City is expected toaddress stormwater quality to receiving streams. Where possible, BMPs should be implementedin new and existing developed areas to reduce the pollution potential from urban runoff. As theCopper Slough is not listed as an impaired stream, the West Washington Street watershed wouldbe an ideal location in which to practice measures aimed at reducing pollution throughstormwater BMPs as a proactive measure.4.7 West Washington Street Watershed BaseflowThere is significant baseflow within the West Washington Street trunk storm sewer during dryweather, sometimes flowing a third full a week after a precipitation event. There are no identifiedsources of this baseflow, although possible water main leaks, groundwater infiltration and othersources are all being considered by the City. Sewer televising has not produced any clear sourcesof storm sewer inflows, although the City will continue to investigate the sewers in this watershedin order to reduce the baseflow in the West Washington Street trunk sewer.September 20094-6Clark Dietz, Inc.