Surface Water Hydrology and Hydraulics - Watersheds, Illinois State Water Survey

Surface Water Hydrology and Hydraulics

Johnson County

Installation of Newbury Riffles in the Cache River to Stabilize the Streambed and Enhance Habitat

Principal Investigators: William P. White

Project Staff: John Beardsley, Jon Rodsater, Long Duong

Sponsor: Illinois Department of Natural Resources

Project Period: June 2003 - December 2004

The Cache River Watershed in southern Illinois is unique and listed as a “Wetland of International Importance.” Channelization of the Cache River along with other alterations to the natural hydrology, habitat fragmentation and excessive erosion and water pollution have been issues that local, state, and federal interests have been trying to collectively combat for years. The State Water Survey in the Office of Scientific Research and Analysis was asked to design and install structures to counteract the negative effects of channel down-cutting in an effort to save the precious wetlands. The ISWS/Surface Water Hydrology and Hydraulics section modified designs of riffle/pool structures, sited the structures and supervised the construction of the riffle/pool structures in the Cache River. Further research on the effects is planned.

Findings to Date:

Twenty five (25) riffle/pool structures were installed over that last two years utilizing 29,000 tons of rock. The structures are working as intended to naturalize stream flow and prevent erosion of the channel bed which further protects the adjacent and highly rich wetlands from being drained. The effort also provided pools behind the riffles which dissipate energy and decrease the amount of sediment and overall water pollution being contributed from stream erosion. The riffles also provide habitat for macroinvertebrates and other aquatic species and oxygenates the water to help further improve overall water quality. Implementation of these and other restoration efforts in recent years has helped guarantee that this great natural resource can be preserved for generations to come.

Project Publications:

Letter Report

Looking into the depths of Heron Pond, a natural resource protected by the riffle structures.
A completed riffle structure in the Cache River, the large boulders average 4’ in diameter.
Excavator working on the downstream backface of a riffle structure in the Cache River.
A riffle structure subjected to flooding in the Cache River.
Project staff inspecting a riffle structure in the Cache River.

Illinois State Water Survey

2204 Griffith Dr
Champaign, IL 61820-7463

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