CORRELATION BETWEEN OBSERVED LAND USE AND PRESENCE OF HUMAN INDICATORS IN GROUNDWATER IN SPRINGFED WETLANDS OF DOOR COUNTY, WISCONSIN

Human and agricultural indicators can be used to link land-use to groundwater discharge quality and might provide an early signal of potential degradation. In Door County, Wisconsin, the presence of artificial chemicals, indicating human influence or contact with groundwater, in spring discharge appears to correlate with observed land-use within the groundwater contribution areas. Door county springs in six wetlands were chosen for study to provide different mixes of land-use within their contribution areas. Water samples were analyzed for bacteria, major ions, metals, agricultural indicators (more than 50 pesticides), and human indicators (artificial sweeteners, caffeine, and pharmaceuticals). Indicators must have measured at or above the limit of detection to be considered present. Observed land-use comprises agricultural, residential, and natural areas.

Human indicators are present when contribution areas contain mostly agricultural or residential land-use. Artificial sweeteners, an indicator of human waste leeched from septic systems, are present at two-thirds of the spring discharge locations. Caffeine, another indicator of human waste, was detected at one site and its presence is likely related to a small population center within the contributing area. None of the pharmaceuticals analyzed were detected. Half of the wetlands show the presence of metolachlor ESA, a degradation product of the commonly-used herbicide, metolachlor. These wetlands have contribution areas with significant agricultural land. None of the other pesticides were detected. Enterococci is a fecal bacteria produced by animal and human wastes and is present at two-thirds of the spring discharge locations

The presence of human indicators appears to correlate with land use when comparing the water quality analysis to land-use data in mapped groundwater contributing areas. Further study will attempt to quantify the correlation between land use and these indicators. This method shows promise for improvement of nutrient management for preservation of Hine’s Emerald Dragonfly habitat, as well as preservation of river, creek, and lake quality into the future.