Letter of No Wetland Impact (LONI)
Many proposed development sites in Lake County, Illinois, contain Waters of the United States (WOUS) and/or Isolated Waters of Lake County (IWLC). However, developments frequently are designed to avoid wetland impacts. In such cases, the enforcement officer for the certified community where the development will occur (or the Lake County Stormwater Management Commission, SMC, for non-certified communities) has the discretion to request that the applicant obtain a LONI from the community’s certified wetland specialist or from SMC’s Certified Wetland Specialist (CWS) for non-IWLC certified communities to confirm that the design will not impact WOUS or IWLC.
The following items are needed for the certified community/SMC’s CWS to perform the LONI review:
- A cover letter clearly describing the proposed development activity.
- Site development plans (particularly grading, utility, and soil erosion/sediment control plans), including the boundaries of all wetlands and other water bodies on the site.
- An “80-150” wetland hydrology analysis, when there is a modification of tributary drainage area or surface runoff volume to preserved IWLC on the development site (refer to Section IV.E.6. in the WDO for details on the “80-150” wetland hydrology requirement in the WDO. Note: the 80-150 wetland hydrology requirement does not apply for preserved WOUS.
- For preserved WOUS only, if required by SMC or the IWLC-certified community: A letter from the U.S. Army Corps of Engineers (USACE) stating the proposed development will not impact the WOUS. This item typically is requested only on “very close calls,” based on the proximity of the proposed site development to the WOUS (e.g., proposed grading within ±10 feet of a delineated WOUS boundary).