Construction of vegetated settling ponds to reduce sediment loading and non-point source pollution in Lake Michigan
Northeastern Illinois University
Basin Program Funds:
Urbanization along many of the shores of Great Lakes has led to increased levels of nonpoint source pollutants entering the lakes through actively eroding wooded ravines.
A recent demonstration project restoring natural streambed armor in ravines (Shabica, 1998) has shown that stormwater erodes more than 3,000 tons of sediment annually from 11 miles of Highland Park, Illinois ravines. Five years of monitoring showed that restoration of streambed armor is a cost-effective, environmentally sound method for reducing ravine bank and ravine bed erosion and consequent nonpoint source sediment loading into the Great Lakes. However, after 5 years, sediments from upstream sources began bypassing the system as the section of the ravine with new streambed armor filled with sediment. We feel that construction of a broad pond in the lower reaches of a ravine, with its greater storage capacity will provide a long-term and effective system for reducing sediment and pollutant loading to the lake.
This project represents a collaborative effort between Great Lakes Shore & Beach Preservation Association and Northeastern Illinois University (NEIU) with students from New Trier High School to implement and monitor methods for reducing nonpoint source sediment loading to Lake Michigan.
The intent of this demonstration project is to test a method for reduction of sediment loading through construction of vegetated settling basins "beaver ponds" in a Glencoe, Illinois ravine.
We propose to construct a check dam near the base of the ravine, re-grade eroding banks as necessary and plant shade tolerant species along the banks of the newly created pond. Ravines are primary conduits for water born pollutants entering Lake Michigan. The retention ponds will help reduce ravine stream bank and stream bed erosion and non-point source pollutants flowing into the Lake. Monitoring will be carried out by measuring the rate of build-up and amount of sediment trapped in the newly constructed settling pond. Information will be disseminated through class reports by the high school and university students. Two workshops will be held where the students, researchers and members of the community can meet and discuss project goals and objectives and monitoring results.
Installation of two retention ponds in the lower reaches of a Glencoe, Illinois ravine that flows directly into Lake Michigan was completed. Following the installation of the dams and ponds, shade tolerant native species were planted along the banks of the settling ponds in spring 2004. Buchanan Consulting, Inc. (BCI) supplied and installed three native seed mixes designed for the three community types present at the project site: shaded streamside, upland wooded slope, and sandy-clay upper beach.
After seed installation a light-weight erosion control fabric was placed on both stream banks to further stabilize the stream bank slopes and promote successful seed germination. Following seed and erosion control blanket installation, BCI installed approximately 200 live plant plugs along the streamside to achieve an immediate cover and stabilization benefit. The survivability of the installed seed and plants was monitored. Seedlings were observed and the stream banks appear to be filling in with vegetation nicely. The tree canopy on the south slope of the ravine was thinned by removing non-native trees to promote growth of surface vegetation.
Sedimentation rate monitoring of the ponds was continued from the previous reporting period. Measurements of accumulated sediment were recorded adjacent to steel monitoring rods installed into the ravine bed in the settling ponds. Measurements were made using a stadia rod and recorded to the tenth of a foot. A detailed post construction topographic survey of the project site was conducted on December 2, 2004 by Terrapin Geomatics Consultants.
Contact: Mr. Jason Meshberg, 847-446-1436