Challenges with Defining Fisheries Targets in Large Urban Systems – The Chicago Area Waterway System
Aquatic systems provide a wide array of essential services, and these systems are particularly vulnerable to adverse affects when located within dense urban populations. Although many studies have examined the variety of water quality and habitat-altering stressors affecting biota within
urban systems, few have examined these adverse effects within large urban waterways. Determining patterns of ecological condition in the fisheries is difficult in least-impacted large systems, and urban effects such as stormwater runoff and impoundments can further obscure condition assessments
and the development of targets for fisheries management. This study describes the challenges encountered and approaches used in defining fisheries targets within a large, urban, constructed, and heavily regulated system that was constructed for conveying wastewater and urban drainage and navigational
The Chicago Area Waterway System (CAWS) is a man-made system designed and managed for urban stormwater and wastewater conveyance, and navigation. In 1889, the Illinois State Legislature created the Chicago Sanitary District (now the Metropolitan Water Reclamation District of Greater
Chicago [the District]) to provide flood control and wastewater management for the Chicago area to protect the public drinking water supply in Lake Michigan and to connect the Great Lakes with the Mississippi River to promote expansion of regional commerce. The approach adopted by the Sanitary
District at that time was to construct canals, locks, and connecting channels to reverse the flow away from Lake Michigan to the Mississippi River. Construction of this system was completed in the early 1900's, resulting in approximately 78 miles of large, constructed, heavily modified
and hydrologically managed channels. Since its construction, the District has constructed and operated numerous facilities along the CAWS, including water reclamation plants, several flow control works and pumping stations, navigational locks, and in-stream and side-stream aeration stations.
The wastewater treatment plants that discharge to the CAWS include the Calumet, Lemont, North Side, and Stickney water reclamation plants, with the flow contribution from these facilities accounting for approximately 70% of the annual system flow. As technologies for water treatment have been
employed, water quality within the CAWS has improved.
In 2007, the Illinois EPA proposed new water quality standards for the CAWS that included designations for aquatic life uses in an effort to respond to water quality improvements. If adopted as proposed, these uses would require a massive
investment by the District to provide additional supplemental instream technologies to improve flow and dissolved oxygen, with associated adverse environmental and aesthetic impacts, including increases in greenhouse gas emissions. The District was concerned that the proposed designations
were based primarily on water quality (without understanding the resultant improvement in fisheries) and that they did not consider the potentially limiting habitat or adverse effects of navigation within this man- made system. An extensive assessment of habitat and habitat improvement potential
was recently completed by the District to inform the development of appropriate designated uses. This study, along with other biological, engineering, and water quality assessments, suggests that establishing a biotic target for the CAWS should be unique. This is because the historic and existing
uses within the system will likely continue to limit the biotic potential, and the habitat within the CAWS is limited and unnatural. Reasonable and achievable goals for this unique system require a rethinking of how terms like “restoration,” “rehabilitation,” or “improvement”
are used in the management and regulation of these man-made systems.
This paper will document the approach used by the District and other stakeholders to establish reasonable management goals for the CAWS so that attainable Clean Water Act uses are ultimately established. These goals, though
possibly falling short of “restoring” natural habitat, seek to improve ecological functions in the CAWS.
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