DuPage County Stormwater Permits

Some municipalities (complete waiver communities) choose to review and process all aspects of the stormwater permit, while others (non-waiver and partial waiver communities) review all aspects except for development in Special Management Areas. It is important to contact your municipality to determine their status and preference for processing stormwater permits. Applicants for developments in unincorporated DuPage County may apply for stormwater permit directly through DuPage County.

SPECIAL MANAGEMENT AREAS

Special Management Areas (SMAs) include wetlands and wetland buffers, riparian areas and regulatory flood plain.

Wetlands are protected by both federal and local regulations, governed by the U.S. Army Corps of Engineers and DuPage County. Proposed development plans must first attempt to avoid and then minimize direct or indirect impacts to a wetland. A direct impact is defined as the removal of vegetation, compaction or mixing of soils, change of grade, dredge, or fill in a wetland. An indirect impact is defined as causing a change in water levels or sediment deposits that may cause a change in the existing plant community type; ie: wet prairie to emergent. Avoidance and minimization of direct impacts may involve reconfiguring the site, and/or reducing the number of lots or building space. Avoidance of indirect impacts may involve moving grading or structures out of the tributary area of a wetland or an analysis of the stormwater runoff entering a wetland to ensure that the elevation and duration of saturation or standing water is not altered. If avoidance is impracticable (see the DuPage Countywide Stormwater and Floodplain Ordinance), the loss of the wetland and buffer must be mitigated, or replaced. Documentation that impacts to a wetland cannot be avoided by the proposed development must be well documented in a Stormwater Permit Submittal.

Wetlands less than 0.10 Acre
As of January, 2004, documentation of avoidance and minimization of wetland impacts is not necessary when the total area of wetland, including Water of DuPage, measures less than 0.10 acre. A Stormwater Permit and wetland mitigation are still required for impacts less than 0.10 acre.

Mitigation
If impacts to an SMA are approved, mitigation is often required to replace or restore the benefits of a resource. Wetland mitigation is the creation of a wetland in an upland (non-wetland) area in the same watershed. Mitigation credit is determined by multiplying the actual acreage of wetland impact by the appropriate replacement ratio. Replacement ratios differ between the two categories of wetlands which are listed in the Ordinance as Critical (high quality) or Regulatory. Regulatory wetland impacts are replaced at 1.5:1 and critical wetland impacts are replaced at 3:1.

Wetland mitigation is the responsibility of the applicant. When designing a site plan that will require wetland impact, the applicant should plan for onsite or offsite mitigation. The created wetland should have a naturalized buffer of at least 50 feet that is entirely contained on the applicant's property. The creation of a successful wetland mitigation facility requires careful planning with the help of an environmental specialist and a civil engineer. Some of the required documentation for wetland mitigation includes a hydroperiod analysis, a planting plan, and a management and monitoring plan with performance standards and an implementation schedule that must be followed by the applicant in order to achieve sign off from DuPage County EDP.

If the applicant can show that onsite or offsite mitigation is not practicable, payment into an approved wetland bank is sometimes an option. A wetland bank is a large wetland creation project (usually greater than 10 acres) that offers to sell created wetland acreage to satisfy permit requirements. In exchange for a fee, the banker takes the responsibility of maintaining and monitoring the mitigation site. Like onsite and offsite mitigation, creation of wetland must take place in the same watershed as the impact.

If there are no credits available in local wetland banks at the time of permit submittal, the applicant may be able to pay into DuPage County's Fee in Lieu of Wetland Mitigation Banking Fund. This fund was set up to accommodate requests for credit and may be utilized only if there are no suitable wetland banks available and the area of wetland impact falls below the mitigation threshold set by the Army Corps of Engineers, Chicago District (applies to jurisdictional wetlands). The cost wetland banking varies by project, but the cost of the Fee in Lieu of Wetland Mitigation Banking fund is set by ordinance at $175,000 per acre.

Example mitigation cost calculation
Area of impact = 0.10 acre
Type of wetland is regulatory ---> mitigation ratio = 1.5:1
Cost of mitigation = $175,000 per acre*

0.10 X 1.5 = 0.15 acres of mitigation credit required

0.15 X $175,000 = $26,250 is the cost of mitigation

* This example uses the cost of DuPage County Fee in Lieu of Wetland Mitigation Banking Fund

WETLAND BUFFER AND RIPARIAN

Wetland Buffers are areas surrounding wetlands that help to protect and support the functions of the wetland. All wetlands in DuPage County have a regulated buffer of 50 to 100 feet depending on the quality of the wetland. Buffers provide habitat for wildlife that depend on the wetlands for survival. The buffer vegetation also helps to slow down storm water runoff, helping to cleanse the water by filtering out pollutants, such as fertilizer, pesticides, and sediment. The buffers around wetlands sometimes even allow the wetland to expand without entering into developed areas during flood events.

A riparian environment, as regulated by DuPage County, is the vegetated area within the regulatory floodplain that provides habitat for vegetation and/or wildlife dependent on the proximity to water. Riparian areas in DuPage County are often dominated by tree and shrub species.

If the proposed development must impact a buffer or riparian area, the applicant must mitigate the functions of the vegetation and soils by replacing them in kind. For example, a wooded area that may provide shading to reduce water temperature in a stream, shelter and food for wildlife, and infiltration of stormwater, would require a planting plan featuring the types of native vegetation that would best replace all of the functions identified. Documenting proper buffer and riparian mitigation in the stormwater submittal involves providing a native planting plan featuring a management and monitoring plan.

FEDERAL, STATE, AND REGIONAL

Impacts to certain areas may require permits and/or approvals directly from Federal agencies such as the U.S. Army Corps of Engineers, U.S. Fish and Wildlife, and U.S. Environmental Protection Agency. Approvals may also be required from state agencies such as Illinois Department of Natural Resources, Illinois Environmental Protection Agency, and Illinois Historic Preservation Agency.
Please contact Kane/DuPage Soil and Water Conservation District for more information about proper sediment and erosion control during construction.

For more information about DuPage County regulations in Special Management areas or to set up a pre-application meeting, please call (630) 407-6700 or click here to view the Stormwater Permitting Information Page.