Reducing erosion in ravine

will improve Lake Michigan

Curbing storm water runoff and reducing erosion in a ravine near Chicago will keep hundreds of tons of sediment from washing into Lake Michigan.

Description

A ravine that slices through the Village of Lake Bluff is one of about three dozen ravines along the western Lake Michigan shoreline, from Chicago to the Wisconsin border. The ravines naturally collect storm water runoff and snowmelt from the surrounding landscape and transport it to Lake Michigan. The construction of homes, roads and shopping centers along the Lake Michigan coast in recent years covered vast areas of the landscape with concrete and other impervious surfaces. Communities along the shoreline also pipe storm water into some of the ravines. The result: Flash floods in the ravines that have caused severe erosion of the stream channel and adjacent stream banks.  The erosion has resulted in the loss of property along several ravines, including the Lake Bluff Ravine. That erosion sends tons of excess sediment into Lake Michigan every year, where it fouls water quality and harms fish and wildlife habitat. Erosion has been a problem in the Lake Bluff Ravine for more than two decades, to the extent that it threatened to consume parts of two local roads. The village tried to stem erosion in a small section of the 3,500-foot-long ravine in the early 1990s, but lacked the funds to completely solve the problem. Armed with a grant from the Great Lakes Restoration Initiative, the Village of Lake Bluff in 2011 took another stab at halting excessive erosion in the ravine. Crews removed trees and other debris from the stream at the bottom of the ravine, restored its natural channel and armored 1,600 feet of eroding stream banks with stone and vegetation. Storm sewer outfalls were repaired to reduce erosion in the ravine, and several small check dams were placed in the stream to slow the flow of water, thereby reducing erosion. Completed in 2013, the project is expected to reduce the amount of sediment washing into Lake Michigan from the Lake Bluff Ravine by 302 tons annually. In addition to reducing erosion, the Lake Bluff project enhanced recreational opportunities in and around the ravine, which is already home to popular hiking and biking trails.

Resource Challenges Addressed

  • Flash flooding
  • Severe stream bank erosion
  • Loss of fish and wildlife habitat
  • Excess sediment into Lake Michigan

LAKE BLUFF RAVINE RESTORATION

Beach looking out over Lake Michigan

Ravine ecosystems like the one pictured above provide habitat for specialized plants in northern Illinois. Credit: Illinois-Indiana Sea Grant.

Results and Accomplishments

The project stabilized eroding stream banks along nearly half of the 3,500-feet long ravine, restored the stream’s natural channel and repaired storm drains that exacerbated erosion in the ravine. The project is expected to reduce the amount of sediment washing into Lake Michigan from the ravine by 302 tons annually, which will improve water quality and fish habitat.