Wetlands are unique features on the landscape, both from a naturalist perspective as well as a regulatory one. Just as lake levels rise and fall throughout the years, wetlands grow and shrink over time. This can be attributed to conditions such as groundwater levels, record-breaking snowfall, droughts, and higher-than-average precipitation. Man-made alterations such as increased impervious areas or alterations to drainage patterns can also have an impact on the size and type of a wetland.
A wetland delineation will determine the lateral extent of the wetlands on a property. Wetland permits and other regulations would apply to this delineated wetland area. A delineation should be performed during the "growing season," which is usually between April and October, by someone knowledgeable in the soils, hydrology and plant indicators that are used to determine where a wetland stops and the upland area begins. Since wetlands can grow and shrink by many feet over just a few years, wetland delineations are only considered valid for a few years (could be 2-3 years in certain parts of Illinois; typically 5 years in Wisconsin).
Prior to gathering field data, a wetland delineator will review current and historic maps, photos, soil types, recent weather data and more. Actual field work will include identification of plants and observations of hydrology and soils up to 24 inches below the surface with flags being placed along the boundary of the wetlands for surveyors to record.
Once wetlands have been field delineated and the type of wetland has been established, plans can be made to protect, restore or fill the wetlands; buffers can be established around the wetlands, property values can be determined, and more.
