The Lake County Wetland Inventory (LCWI) maps natural and artificial wetlands meeting definitions established by the federal agencies who work with the Lake County Geographic Information System staff to periodically review and update it. These agencies include the United States Environmental Protection Agency, the U.S. Fish and Wildlife Service, the USDA Natural Resources Conservation Service and the United States Army Corps of Engineers.

The 1989 federal wetland delineation standards for offsite wetland mapping are used. This data was last published in March of 1993. This update includes changes to the previous version of LCWI including: adjust current wetland boundaries to omit development, including roads; to fine tune boundary placement where that was intended by the original delineation, in some cases, adjust the wetland to photographic features / signature; delete wetlands which the committee decided were mapped in error - for example, trees which were mistaken for wet areas; create polygons for newly delineated artificial wetlands; and newly delineated wetlands or farmed wetlands caused by the continued deterioration of the agricultural drain tile system and increased runoff due to urbanization.

The LCWI is a useful tool for general planning and review purposes, but it does not take the place of an on-site delineation by a certified wetland specialist.

High resolution (1" = 100') orthorectified aerial imagery captured in April 2002 was used as the base for this update. Other data used as reference for this update include: 2004 SOIL SURVEY GEOGRAPHIC (SSURGO) DATABASE FOR LAKE COUNTY, IL - U.S. Department of Agriculture, Natural Resources Conservation Service; HYDROLOGY2002 - Lake County GIS/Map Division; 2' topography (CONTOURS) - Lake County GIS/Map Division; and various years of historical aerial photography for clarification. By using the more recent higher resolution photography, the resulting updated wetland boundaries are more accurate then the original boundaries published in 1993.