Comprehensive wastewater treatment planning is an integral part of maintaining the quality of our region's waters. Although significant accomplishments in wastewater planning have improved the quality of our surface waters, many of the region's urban streams and rivers and many of its lakes still do not meet the goals of the Clean Water Act" (NIPC, 34) requiring fishable and swimmable" conditions" (NIPC 2000). This is due to numerous causes, from both point source and nonpoint source pollution. The U.S. Environmental Protection Agency (USEPA) established the National Pollution Discharge Elimination System (NPDES) to help achieve the goals of the Clean Water Act. The NPDES program was designed to control "water pollution sources by regulating point sources that discharge pollutants into waters of the United States" USEPA, Office of Wastewater Management).
Point Source Pollution
The USEPA has delegated authority to the Illinois Environmental Protection Agency [IEPA] to administer the NPDES permit system program in our state. As of 2003, Northeastern Illinois Planning Commission (NIPC) records indicate that there were 108 NPDES permits from public wastewater treatment plants in northeastern Illinois, with an additional 379 NPDES permits from other sources. Despite these efforts to control point sources, most of the region's surface waters are still degraded and incapable of attaining primary contact status.* Because they are degraded, "urban waterways are unable to dilute even highly treated discharges, resulting in problems like low dissolved oxygen levels that are damaging to aquatic life" (NIPC 2000, 61). Small treatment plants that discharge into low flow and/or high quality streams are of particular concern as they may not provide consistent levels of treatment. Please refer to the Conservation Design and Stormwater Best Management Practice strategy paper (coming soon) for a more thorough discussion.
Combined Sewer Overflows and Sanitary Sewer Overflows
Exacerbating the impacts of point source pollution, overflows from combined sewers (CSOs) and sanitary sewers (SSOs) further degrade our region's waterbodies by discharging untreated or poorly treated wastewater and stormwater into area surface waters. Many older communities throughout northeastern Illinois have combined sewers for both sanitary wastewater and stormwater runoff. While there are no isolated figures for northeastern Illinois, the USEPA estimates that the volume of combined sewer overflows nationwide is 850 billion gallons per year (American Society of Civil Engineers).
Combined sewer overflows, which occur after wet weather events, are as much a result of poor stormwater management as they are insufficient treatment capacity at the wastewater treatment facility. CSOs can be prevented through improving infrastructure such as separating stormwater and sewer lines. However, these solutions can be very costly. Better stormwater management, which keeps stormwater onsite and construction of sufficient retention capacity, can alleviate CSOs, making it more cost effective.
Sanitary sewer overflows often result from insufficient sewer capacity, infiltration of stormwater, inflow from unknown connections, blockage or other infrastructure problems. Infrastructure planning and maintenance can prevent many SSOs.
Non-point Source Pollution
While impacts from point sources are significant, nonpoint sources of pollution also adversely impact water quality throughout northeastern Illinois. Primary causes of nonpoint source pollution include stormwater runoff from impervious surfaces and construction sites, channel modification, urban runoff, and draining and filling of wetlands. Effective control of such sources is an indispensable component of a comprehensive strategy for preventing impairment of the region's waterways.
*Primary contact status, according to Illinois Water Quality Standards, means "any recreational or other water use in which there is prolonged and intimate contact with the water involving considerable risk of ingesting water in quantities sufficient to pose a significant health hazard such as swimming and water skiing" (35 Ill. Adm. Code 301.355).