Author(s): Charles S. Melching
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Keywords: Water quality modeling; Dissolved oxygen; Combined sewer overflows; Water quality management
Abstract: The Metropolitan Water Reclamation District of Greater Chicago is allowed to divert an annual average flow of 7. 65 m3/s from Lake Michigan to improve water quality in the Chicago Area Waterways System (CAWS). A modeling study was done to determine if compliance with dissolved oxygen (DO) standards could be improved on the North Shore Channel (NSC) without adversely affecting compliance with the DO standards anywhere else in the CAWS while staying within the discretionary diversion limit. The DUFLOW modeling system developed in the Netherlands has been adapted to simulate water quality in the CAWS. This model was applied to evaluate the reallocation of discretionary diversion from Lake Michigan for three representative water years, a wet year (2008), dry year (2003), and medium year (2001). It was found that by reallocating the discretionary diversion within the CAWS full compliance with the DO standards could be achieved at Simpson Street and Main Street on the NSC during dry weather. Compliance over the entire year from 95. 8 to 97. 0% at Simpson Street and from 92. 0 to 96. 7% at Main Street could be achieved without negatively affecting compliance anywhere else in the CAWS, as opposed to 66. 9 to 78. 0% and 70. 0 to 89. 8% compliance at Simpson Street and Main Street, respectively, for the actual discretionary diversion taken in WYs 2001, 2003, and 2008.
Year: 2013