Opportunities and Challenges for Incorporating Threshold Effects in Linked Surface/Groundwater Management
Monday, December 4, 2017
101 AB (Music City Center)
The accelerating impacts of landuse changes driven by development in areas outside of urban centers have highlighted the imperative for integrated management of surface and groundwater resources. Although judicial rulings have provided government agencies authority to utilize the potential impacts of groundwater reduction on surface waters to inform management decisions, these agencies are not equipped with standardized processes to gather the information necessary to exercise their authority. This gap has created regulatory uncertainty and fostered conflict around linked surface and groundwater resources (LSGR) management. Lake Beulah is a multi-basin marl lake in Walworth County, Wisconsin where concerns over the potential impact of groundwater withdrawal on lake water quality resulted in a lengthy legal battle between lake residents, local government, and the Wisconsin Department of Natural Resources (WDNR). In this study we first employed the US Army Corps of Engineers reservoir/lake model BATHTUB in combination with geochemical model PHREEQC to identify an impact threshold value for groundwater reduction for Lake Beulah. Groundwater withdrawal reduces the resilience of Lake Beulah to nutrient loading through the established Ca2+ - P co-precipitation mechanism, and effects were not uniform across basins. It remains to be seen as to whether state agencies in Wisconsin will utilize decision frameworks in making management decisions in LSGR systems. Ongoing challenges to court rulings and interpretations of agency authority continue to obfuscate whether WDNR will be allowed to consider the cumulative effects of multiple wells in assessing significant adverse impacts. A critical discussion of the utility of decision support frameworks outlines the need for boundary work to identify how it can be used to effectively govern LSGR.