Working Cooperatively to Investigate, Assess, and Monitor Wetlands
Hydrogeology, geomorphology, biology, botany, and pedology are all needed to investigate, assess, and monitor wetland areas. To obtain expertise in all of these areas, ISGS scientists work cooperatively with the Illinois Natural History Survey (INHS), Illinois State Water Survey (ISWS), Illinois Department of Transportation (IDOT), and Illinois Department of Natural Resources (IDNR).
IDOT provides program funding to ISGS and INHS scientists to help IDOT meet the regulatory requirements for wetland creation, mitigation, and restoration as part of the state transportation construction program. The state realizes the importance of wetland areas: they help to purify run-off water, provide run-off buffers that mitigate urban flooding, and support diverse plant and animal life. If natural wetlands are damaged or destroyed through roadway construction, they must be restored or created elsewhere in the impacted drainage basin.
ISGS hydrogeologists examine IDOT sites throughout the state for their potential as wetland compensation areas (or "banks") where wetlands can be created or restored. ISGS hydrogeologists are currently studying large (hundreds of acres) wetland bank sites in the Chicago Metro area, St. Louis Metro East area, Fayette County, and Illinois River floodplain sites in Grundy County near Morris and in Brown County near Meredosia. Some currently think these larger sites can provide a more sustainable environment for a wider variety of plant and animal species. Smaller (tens of acres) IDOT sites, however, have also met with success, as shown by the following examples.
Van Patten Woods Forest Preserve, Lake County
The selected compensation site was adjacent to a sedge meadow and marsh wetland, which requires both a wet season and a drier season to function. ISGS hydrogeologists investigated the hydrology of the compensation site and compared it with the adjacent wetland.
They evaluated differences between the sites and recommended shallow (50 cm) excavation to match the existing sedge meadow. Excavation resulted in an area where water fluctuates seasonally, mimicking the existing wetland and allowing the sedge to reproduce. Water-level data for the first five years after construction of the wetland in 1995 show that the entire excavated basin satisfies the wetland hydrology criteria of the U.S. Army Corps of Engineers.
Hickory Grove Highlands Conservation District Site, McHenry County
In 1993, the McHenry County Conservation District offered a site for attempting fen-wetland restoration. ISGS and INHS scientists identified the drainage alterations—underground field tiles and excavated ditches—that had drained part of the fen, the peat mound, and adjacent non-wetland areas.
These drainage changes also allowed several encroaching woody species to invade and dominate the former wetland area. After IDOT and the McHenry County Conservation District removed the hydrologic alterations and the woody vegetation, portions of the site were replanted with native fen, wetland, and prairie plant species.
Although some of the area does not meet the criteria for a wetland, recovery is expected to progress as groundwater flows are reestablished.
The Nature Preserve Commission of IDNR funds a second ISGS wetland program, which was set up to assist the Nature Preserve staff in monitoring the effects of groundwater contamination or flow modification from surrounding land use or development on selected sites. The program also advises regional site staff on how to best maintain site hydrology to support preserve goals.
Lake in the Hills Fen Nature Preserve, McHenry County
ISGS and ISWS hydrogeologists in this program worked together with IDNR staff to assess the potential threats to the preserve and to design an action agenda with the goal of minimizing short- and long-term groundwater impacts to the nature preserve. Gravel pit development adjacent to the preserve was thought to have changed groundwater discharge patterns and chemistry.
Also, a municipal center was being planned for construction within the preserve's recharge area. Partially as a result of this assessment, IDNR purchased 70 acres of unmined land within a critical recharge area, pre-mining conditions near one fen are being restored, and the village of Lake in the Hills is seeking an alternate location for its municipal center.
Updated 05/18/2011 SLD