Cache River (Illinois) - Drainage and Diversion

Drainage and Diversion

After most of the accessible timber was cut, local industry shifted to agriculture, and a program of diversion and draining began. The landscape changed dramatically, largely due to a diversion channel that was cut to connect the Cache and the nearby Ohio River. Constructed in 1912-1915, the Post Creek Cutoff divided the Cache into two watersheds; the Upper Cache, which drains down the diversion channel to the Ohio; and the Lower Cache, which drains to the original outlet on the Mississippi River. In 1952, the Karnak levee was constructed, further cementing the division between the two rivers.

In 1950, about 11 miles (18 km) north of the Cache’s natural mouth at the Ohio River, a diversion channel was created to connect the Cache and Mississippi rivers. Those last 11 miles (18 km) of the Cache continue to drain into the Ohio through the original channel.

In 2002, the levee dividing the Post Creek Cutoff and the Lower Cache suffered a catastrophic failure during the spring flood season. The failure of the levee has resulted in dropping water levels in the Lower Cache. An interesting effect of this diversion is that in times of high water direction of flow on the lower Cache reverses, flowing east to the diversion channel. When the water level in the lower Cache drops below the diversion channel level, flow resumes its westerly travel to the Mississippi. Also, because of the breach, this section of the Cache is exposed to increased risk from flooding.

The future of the levee, however, remains uncertain. Management of the levee falls to Big Creek Drainage District No. 2. The U.S. Army Corps of Engineers no longer considers the levee in its programs, making it ineligible for federal funding.

The Cache River Wetlands Joint Venture Partnership – composed of Ducks Unlimited, Illinois Department of Natural Resources, Natural Resources Conservation Service, The Nature Conservancy and U.S. Fish and Wildlife Service — is considering a restoration project that could repair the levee as part of its efforts to restore low water flow. To date, two reports on this subject, created by the Center for Watershed Science at the Illinois State Water Survey, are publicly available.