High chloride concentrations are toxic to aquatic life. Exposure over the long-term (chronic) and short-term (acute) are both harmful. Over the past 50 years surface water chloride concentrations have increased across Wisconsin. While concentrations are highest in urban areas with dense road networks and large winter salt application, waters across the state are impacted.

In 2016, portions of both branches of Starkweather Creek were listed as impaired by WDNR for chloride chronic aquatic toxicity. A water body is deemed to have chloride toxicity in WI if maximum daily chloride concentrations over four consecutive days average to be more than 395 mg/L (chronic) or 757 mg/L (acute) two or more times within a three-year period.

Since 2020 the Friends of Starkweather Creek have been working with the Capital Area Regional Planning Commission (CARPC) and other stakeholders in the watershed on monitoring chloride concentrations in the creek, identifying chloride pollutant sources and management measures, and developing an information and education plan to reduce salt use in Starkweather Creek. You can read a detailed report on the issue in Starkweather Creek or view an interactive map sampling sites and results.

Current efforts include a community-based partnership with CARPC, USGS, and Operation Fresh Start focusing on continuous monitoring of chloride contamination in the Starkweather Creek watershed. You can view the web map and monitoring results.

Most people who are applying salt don’t understand that impacts of salt on our infrastructure and freshwater resources. If you see a resident/neighbor who is overusing salt, please have a conversation with them using the outreach tools developed by WI Salt Wise.

In the City of Madison, over salted public sidewalks can also be reported to the City through their “Sidewalk Concerns” form.