Upper Mississippi River Basin Association (UMRBA) is facilitating cooperative action among state and federal water quality and transportation agencies, local governments, and private salt applicators to reduce rising chloride contamination in the Upper Mississippi River Basin and to improve our understanding of chloride impacts in the basin.
Long term state monitoring programs show chloride concentrations have been rising for several decades – at least by 35 percent throughout the basin from 1989 to 2018. Winter de-icing salt application and municipal wastewater treatment discharge into surface waterbodies throughout the Upper Mississippi River watershed are resulting in rising chloride levels. Elevated chloride levels can harm aquatic ecosystems, mobilize other contaminants, and corrode infrastructure.
While existing solutions for reversing chloride contamination are limited and expensive, there are opportunities to reduce the sources of chloride entering waterbodies within the Upper Mississippi River. Road salt application techniques exist that minimize chloride runoff while ensuring public safety and substantially reducing winter road maintenance costs for municipalities, cities, states, and private applicators. For example, Minnesota’s Smart Salting program (applicator training and certification for private contractors) shows that strategic applications can reduce road salting rates by 30 percent to 70 percent in the Twin Cities Metro Area. State agencies are also exploring options to provide limited liability protection to road salt applicators against ice-related injuries and property damage to provide incentives to minimize salt application.
In 2022, UMRBA adopted a formal resolution describing long term trends, impacts, and current management efforts and calls for a robust set of strategies to accelerate efforts to reduce chloride loading, improve our understanding of chloride impacts, and communicate the issues and management challenges and opportunities.