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The County of DuPage
Wheaton, Illinois

Deep Overwintering Pool

The goal of this project was to provide a deep pool water habitat as an element of a system of restored and created marsh/ wetland complex supporting and connected to the river. This supports a greater diversity and abundance of game and non-game fisheries while providing high water quality input to the river.

The project is located on the Roy C. Blackwell Forest Preserve in DuPage County, IL. The project created a deep-water pool habitat ranging from 10 to 15 feet in depth. Aspects of the pool and channel, such as the littoral shelf, limestone slabs, and downed snags, did not previously exist at the project site location. A littoral zone (wetland shelf) within the pool provides deep emergent habitat and structure as a fish nursery for species such as golden shiners, fathead minnows, mosquito fish, central mudminnows, blackstripe topminnows, pumpkinseeds, and green sunfish; native aquatic plant species were planted within this zone. Additional shallow wetlands are located around the pool perimeter, creating microhabitats and seasonally inundated flats, affording a full complement of aquatic and semi-aquatic transition to the surrounding landscape.

The pool is connected to the river by a channel 10 to 30 feet wide, using natural rock and vegetation for stabilization. Pool excavation and construction activities were coordinated with remedial activities at the adjacent Kerr-McGee Superfund site (the bed and banks of a stretch of the river). Hydric soil was harvested from the site for habitat mitigation activities following removal of contaminated sediments. DuPage County also used removed sediments and woody materials for habitat restoration activities in other county Forest Preserves.

To eliminate large non-desirable fish species and allow the pool community assemblage to develop, for the first few years fish access from the river to the pool is somewhat blocked by an in-stream flow-through boulder structure. Additional habitat variation is found in limestone slabs and overhangs along portions of the pool and channel side slopes; the built-in habitat structures were designed to maximize sheltering and spawning opportunities for fish. Pool water sources include groundwater, overland flow, and floodwaters from the river. Native plants were planted in the fall of 2007 and replanted as needed in the spring of 2008.

Monitoring includes fish species, turbidity, pH, DO, and plants diversity. In 2008, in coordination with the Illinois DNR, non-game fish (State T&E as well as species in need of conservation) from other Illinois locations were introduced into the pool. A 5 year monitoring and maintenance plan is underway at the project site.

Deep Pool During Construction

Deep Pool Construction

Deep Pool Post Construction

Deep Pool Final