Emiquon Preserve water control structure, Fulton County, Illinois

Project Summary

Hanson provided engineering design services for a reinforced concrete water control structure with non-metallic gates and support services for the design of a pump station and elevated control building for The Nature Conservancy (TNC) on a major project at the ecologically significant Emiquon Preserve. The 5,000-acre preserve is on the right descending bank of the Illinois River immediately northwest of Havana, Illinois, and approximately 40 miles southwest of Peoria, Illinois.

Emiquon is one of the largest and most recognized bottomland lakes in the Illinois River Valley. The river valley was renowned for its waterfowl hunting, and the Illinois River was the most productive inland commercial fishery with the most productive mussel stream per mile in North America until it was overharvested and polluted. 

Prior to its isolation from the river in 1920, when levee construction was completed, the Emiquon project area was hydraulically connected to the river and provided premier habitat for diverse aquatic species. The project area was drained for agricultural production and served as productive farmland for more than 80 years. In 2000, TNC announced it had purchased the project area along with additional adjacent lands. The project area continued to be farmed while a restoration plan was developed; in 2006, TNC signed a Wetland Reserve Program (WRP) agreement with the USDA-Natural Resources Conservation Service. In 2007, in cooperation with the WRP agreement, TNC halted pumping and the water levels began to rise, restoring fishery and wetland habitat in this backwater area. However, recent restoration efforts at nearby Hennepin and Hopper lakes were found to be ineffective at promoting ecosystem diversity with unmanaged water levels. Disturbance to the system occurred because of the high concentration of common and grass carp varieties of fish. TNC determined that, without a reliable way to manage water levels at Emiquon, the ecosystem would substantially degrade over time.

"We choose to work with Hanson because of their expertise/experience and relationship." - Doug Blodgett, director of river conservation, The Nature Conservancy

With the objective of managing water levels in 6,000 acres of flooded wetlands, Hanson designed a double-box culvert consisting of two 8-foot-by-8-foot boxes through the levee, with a concrete riser structure and sluice gate on the Illinois River side to accommodate sampling and monitoring of water and biota. The riser structure also functions as the discharge point for a new 60,000 gallons-per-minute pumping station located on the Emiquon Preserve side of the levee.

The project team collaborated with TNC to develop concepts for managing the water levels and ecosystem within Emiquon and to refine alternatives that incorporated innovative access points into the system for water quality monitoring, sampling and field tests to identify aquatic plants and animals, including invasive species. The result was a multi-purpose facility that not only met the stated project requirements for wetlands restoration, a water control structure and a pumping station, but that also incorporated scientific and monitoring goals as functional elements supporting biological and fish monitoring programs. Hanson’s 3-D renderings of the water control structure and pump station were incorporated into TNC’s website and presentations, aiding in the search for donors to fund construction.

A significant aspect of the project was coordination with government organizations including the Illinois Historic Preservation Agency; Illinois Department of Natural Resources-Office of Water Resources; Illinois Department of Natural Resources, Endangered Species; Illinois Environmental Protection Agency; the U.S. Department of Agriculture-Natural Resources Conservation Service; the U.S. Fish and Wildlife Service; and the U.S. Army Corps of Engineers.

Maurer-Stutz and Hanson won an Honor Award from the American Council of Engineering Companies (ACEC-IL) and the Carl V. Anderson Conservation Project of the Year Award from the Association of Conservation Engineers in recognition of the project. Read more about Emiquon here.