Special Management Areas Regulations for Development
DuPage County Stormwater and Floodplain Ordinance Page
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 a
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 County-wide 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.
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 on-site or off-site 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 hydro-period 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
If the applicant can show that on-site or off-site 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 on-site and off-site 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 Illinois Regulations,
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.
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.
Report a violation in a special management area
What is a Special Management Area (SMA)?
Any area containing regulatory flood plain, riparian environment, wetland or wetland buffer areas are considered to be an SMA and need additional documentation before a building permit will be granted.
How do I know if I have an SMA on my property?
Before you plan to build, you will need to determine if you have a one of the above mentioned areas on the property or nearby. It is possible that development on your property will negatively impact an adjoining water ecosystem, and therefore, the impact
would need to be minimized. Floodplain and wetland indicator maps are available at DuPage County for public use, although not all areas have been mapped. These maps are only an indicator that wetlands may be present. Therefore, an environmental specialist
is needed to delineate the location and exact boundaries of any SMA on the property.
For proposed building projects, the DuPage County-wide Stormwater and Floodplain Ordinance states that a wetland delineation, along with a stormwater permit application, must be submitted and approved before a building permit will be granted for new structures.
What are the regulations regarding wetlands?
Wetlands are protected by both federal and local regulations, governed by the US Army Corps of Engineers and DuPage County. Any activity that will impact a wetland or a wetland buffer area must be avoided. If avoidance is impracticable (see the DuPage
County-wide Stormwater and Floodplain Ordinance), the loss of the wetland and buffer must be mitigated, or replaced.
As of January 2004, if the development impact to a regulatory wetland area is less than 0.10 acre, though a Stormwater Permit will be required, documentation of avoidance and minimization of wetland impacts is not necessary.
What are the regulations regarding wetland buffers and riparian areas?
Impacts to wetland buffer and riparian areas can be mitigated by documenting the functions provided by the existing vegetation and replacing those functions 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 the functions identified.). Replacement involves providing a management and monitoring
plan featuring a native planting plan with performance standards.
What is avoidance and minimization of impact?
Any proposed development in or near an SMA must show that no practicable alternatives exist to avoid impact to a wetland or floodplain area. Applicants must first attempt to avoid and then minimize direct impacts (which could include removing vegetation,
filling with soil or other materials or pumping water out of the area) or indirect impacts (such as causing a change in water levels that impact the existing community type).
Avoidance and minimization of direct impacts may involve reconfiguring the site and/or reducing building space or the number of lots. Avoidance of indirect impacts may involve moving grading or structures out of the tributary area of a wetland or floodplain
or an analysis of the stormwater entering the area to ensure that the elevation and duration of saturation is not altered. However, if avoidance or minimization of impacts is not practicable, the reasons for the impacts and plans for mitigation should
be documented in the stormwater permit application.
My building application shows that I am unable to avoid wetland impacts. What is included in the mitigation process?
Mitigation is the replacement of wetland acreage or buffer/riparian functions in the same watershed after proposed impacts have been approved. Wetland mitigation is the responsibility of the applicant. In DuPage County, the replacement ratio for regulatory
wetlands is 1.5:1 while the ratio for critical, or high-quality, wetlands is 3:1.
There are two types of mitigation. The first includes on-site or off-site mitigation. When designing a site plan that will require wetland impacts, the applicant should plan for on-site mitigation. This means that a sustainable wetland system large enough
to fulfill the replacement requirements for the proposed impacts must be created on the same site as the proposed development. If this is not an option, mitigation can occur at an off-site location.
The created wetland should have at least a 50 foot buffer, planted with native vegetation, and the edge of the wetland must be at least 50 feet from the property line, structures, or pavement. On-site mitigation requires a planting plan and schedule with
a management and monitoring plan showing anticipated maintenance of the wetland for at least 5 years from the date of planting. Performance standards to measure planting success in both the created wetland and buffer must be submitted before DuPage
County will release the mitigation site from further maintenance obligations.
The last option for mitigation is wetland banking. If an applicant can show that on-site or off-site mitigation is not practicable, payment into an approved wetland bank is sometimes available. A wetland bank is the creation of a large wetland (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. DuPage County creates wetland banks
as a service to applicants. Like on-site and off-site mitigation, creation of wetlands and purchase of mitigation acres must take place in the same watershed.