- Stormwater Management Commission
- For Local Government
- Wetland Determinations
Wetland Determinations (also called Wetland Delineations
Midwest Regional Wetland Plant List
Wetland delineations performed in Lake County, IL, shall use the current version of the National Wetland Plant List (NWPL) for the Midwest Region. The latest version of this document can be found at the US Army Corps of Engineers NWPL home page. Select the appropriate regional list (i.e., Midwest).
If potential wetlands, farmed wetlands, or other water bodies appear to be present on a proposed development site (based on a review of Lake County online GIS maps; see Online Maps), the Lake County Watershed Development Ordinance (WDO) requires that a wetland determination of the site be performed within three (3) years of an initial permit application date. A wetland determination also should be performed if other resources (e.g., aerial photos) suggest the potential for wetlands or water bodies on the property. Wetland determinations are to be performed by, or under the supervision of, a Lake County Certified Wetland Specialist.
Wetland Determinations on Non-Agricultural Land (Non-Cropland)
The presence and extent of wetlands or other water bodies on non-agricultural lands (i.e., non-croplands) is determined using an on-site procedure in accordance with the current Federal wetland delineation methodology, which includes:
- Corps of Engineers Wetland Delineation Manual. Environmental Laboratory, 1987, online version 1992 (PDF)
- Regional Supplement to the Corps of Engineers Wetland Delineation Manual: Midwest Region, Version 2.0, dated August 2010 (PDF)
The WDO requires that the delineated boundaries of wetlands/waters be flagged or staked and surveyed for inclusion on site development plans and eventual permitting purposes. A field boundary verification is recommended before surveying the locations of wetland flags. See the Jurisdictional Determinations link to the left for more information on boundary verifications.
Wetland Determinations on Agricultural Land (Cropland)
If the proposed development site contains agricultural land (i.e., cropland, pasture land, orchards, vineyards, and nurseries, confined feeding operations and equestrian facilities that are farmed currently, or land that has been farmed at least one year in the last five years), an agricultural land wetland determination needs to be performed following the current federal Natural Resource Conservation Service (NRCS) procedures—as clarified in SMC’s Regulatory Guidance Memorandum for Agricultural Land Wetland Determinations, RGM # 2022-01—to determine if “farmed wetlands” are present on the site. The procedure involves an office review of aerial imagery for certain years followed by a field review to confirm the presence of hydric soil(s) in suspected farmed wetland areas.
Digital imagery (jpeg format) of Food Security Act aerial slides for use in Lake County farmed wetland determinations can be ordered online using the McHenry-Lake SWCD FSA Slides Order Form (PDF). Refer to Section A in the above-referenced SMC Regulatory Guidance Memorandum for Agricultural Land Wetland Determinations, RGM #2022-01 (PDF) for the designated slide years to be reviewed. The slide years depend on which NWS recording station is nearest to your project site: Antioch, Barrington or Highland Park. SMC recommends ordering all indicator slide years—both primary and secondary—for both normal and wet conditions. Note: The online FSA Slides Order Form indicates that 2002 aerial slides are not available; however, that only applies to McHenry County slides; the 2002 aerial slides are available for Lake County sites.
To facilitate SMC’s review of farmed wetland determinations, copies of all aerial images reviewed should be provided with the wetland determination report. Further, we request the determination results be summarized in tabular form (see example in the SMC RGM #2022-01). Digital format (jpeg) is preferred, but SMC also accepts clear, legible color PDFs.
Wetland Determination Report
For development sites with wetlands/waters, the WDO requires the following minimum contents for the Wetland Determination Report. Many of these requirements overlap with Wetland Reporting standards for the Chicago District Corps of Engineers, but there are a few additional elements for the WDO-compliant Wetland Determination Report, including an exhibit for the USGS flood of record (aka hydrologic atlas).
- A plan showing the surveyed boundaries of delineated wetlands/waters within the development site and the approximate boundaries of off-site wetlands/water within the maximum buffer requirements adjoining the development site;
- An aerial photograph showing the development site boundary, on-site delineated wetlands/waters (including field sampling point locations), and approximate boundaries of off-site wetlands/waters on adjoining properties;
- Copies of reference maps* (most recent versions) showing the development site boundary, including the U.S Geological Survey (USGS) quadrangle map, Lake County Wetland Inventory map, Federal Emergency Management Agency (FEMA) floodplain map, Lake County Soil Survey map, and USGS flood of record map (i.e., hydrologic atlas**);
- U.S Army Corps of Engineers data sheets (current version) and color photographs for each representative wetland and upland sampling point*** including data taken in suspect areas;
- A written description of each wetland, including a floristic quality assessment (FQA) using the Chicago Region Floristic Quality Assessment Calculator (current version). FQAs shall generally be conducted between May 15 and October 1, which approximates the growing season for Lake County’s native plant; and
- A farmed wetland determination, if applicable - see the section on "Wetland Determinations on Agricultural Land (Cropland)" above. The approximate boundaries of farmed wetlands on the development site shall be shown on the plan and aerial photograph referenced above.
* Note that inclusion of exhibits for the National Wetland Inventory (NWI) map and/or the Existing Wetland Inventory layer of Lake County’s Wetland Restoration and Preservation Plan (WRAPP) tool is optional.
** Note: The Hydrologic Atlas is not the same as the HUC maps or the FEMA maps. The hydrologic atlas is available via Lake County’s online maps under the Drainage Layer’s “flood of record.”
*** Representative photos of each wetland/water body are optional and do not replace the need for data-point specific photos. Non-growing season floristic assessments may require additional sampling during the growing season (as defined by the WDO) to satisfy WDO requirements.