Vulnerability of Illinois nature preserves to potential ground-water contamination volume I: methodology and initial assessment

"Prepared for Illinois Nature Preserves Commission.""March 1997."The Illinois Nature Preserves Commission (INPC) was created by the Illinois Natural Areas Preservation Act in 1963 (ch. 105, para. 701 et. seq.), with the mission to "assist...landowners in protecting high quality natural areas and habitats of endangered and threatened species in perpetuity, through voluntary dedication of such lands into the Illinois Nature Preserves System." Dedication as a nature preserve provides strong legal protection. For example, penalties for damaging a nature preserve range from a Class A misdemeanor to $10,000 per day in civil penalties. As of December 1996, the Illinois Nature Preserve System consisted of 261 nature preserves that encompass more than 35,000 acres (14,200 hectares) in 73 of the 102 Illinois counties. A significant threat to nature preserves (and other areas with high quality natural communities) is adjacent land use. Variability in adjacent land use generally depends on preserve size and location. Frequently, many different land uses surround a single nature preserve. Potential ground-water contaminant sources include: dumping within or near a preserve, residential septic systems, roads where deicers are used, agricultural fields or feedlots, leaking impoundments or storage tanks, and certain industrial and commercial activities. Unfortunately, the lack of baseline data at most preserves prevents the detection of water quality degradation from off-site activities. During this study, methods were developed and utilized to assess nature preserve sensitivity and vulnerability to potential ground-water contamination. First, a shallow ground-water sensitivity map of the state (1:500,000) was prepared using GIS techniques. It predicts the potential for movement of contaminants from the surface into shallow ground water based on soil leaching characteristics and depth to the uppermost aquifer. Two hundred seven nature preserves were screened, and nearly half of them were categorized as having high or very high sensitivity to ground-water contamination. Second, site surveys were conducted at the 85 nature preserves, which were expected to be most sensitive to ground-water contamination. Hydrologic, geologic, and land-use information was collected for the sites and surrounding areas prior to the surveys. These data were used during the surveys and can be used for future interpretations and comparisons. Roughly 30% of the sites were classified as having moderate-to-high or high vulnerability. The development and use of a field evaluation form facilitated site surveys and the subsequent entry of field data into an electronic database. These types of surveys should be conducted at all nature preserves to provide a standard set of background information for future decision making. Third, the geology and hydrology of Spring Grove Fen Nature Preserve in McHenry County were characterized in greater detail. Test drilling was conducted and 10 observation wells were installed. A total of 64 sets of ground-water and surface water samples were collected between August 1995 and October 1996 and analyzed for a minimum of 35 constituents. Increased chloride concentrations (up to 121 mg/L) were observed in and upgradient of the preserve. Use of deicers on nearby roads may be responsible for an increase in chloride of over 500% at well SG-1a. Low concentrations of alachlor metabolites (< 3 &#956;g/L) were seen in observation wells and in Nippersink Creek. Low concentrations of triazine residues (< 1 &#956;g/L) were also seen in Nippersink Creek. Chemical data at Spring Grove Fen supports the assessment of the site being highly vulnerable to contamination. This type of chemical sampling is important to establish existing water quality at preserves for comparison to future conditions. Information collected during this study is intended to facilitate petitions for state designation of ground water associated with a nature preserve as a Special Resource Ground Water. As stated in the Illinois Administrative Code (Title 35, Part 620.230), Special Resource Ground Water is: a) "demonstrably unique...," or b) "vital for a particularly sensitive ecological system...," or c) "groundwater that contributes to a dedicated nature preserve...." Such a designation may then provide an additional level of protection against destruction or degradation of nature preserves