A Chloride Impact Study for the Southeastern Wisconsin Region

The Commission staff prepared a Prospectus for a comprehensive study of the environmental impacts of the use of chloride on the surface water and groundwater resources of the Region. A Technical Advisory Committee was formed (roster to the right), and that committee met on September 8, 2015, October 21, 2015, and June 5, 2018 (agendas and summary notes under "Meeting Materials" below).

Work began on the study in summer 2017 and to date the Commission staff has focused on the Region-wide monitoring effort outlined in the Prospectus. This includes continuous monitoring for specific conductance at approximately 40 stream locations throughout the Region. Following a detailed site selection process and in-stream monitoring equipment deployment, a two-year comprehensive data collection period began in October 2018 and concluded in October 2020. Additional data collection at selected sites is continuing into spring of 2021. Monthly grab samples were collected at each site, along with targeted event sampling, to obtain water quality data that include chloride concentrations. Additionally, quarterly sampling was performed at six lakes within the Region, collecting temperature, specific conductance, and chloride data at various depths. Figure 1 compares the draft seasonal chloride profiles for two lakes in the Region, Moose Lake and Little Muskego Lake.

Previous studies have demonstrated that specific conductance is a good predictor of chloride concentration once a reliable relationship is established. Specific conductance, collected at 5-minute intervals at each monitoring site, is paired with the corresponding chloride concentration obtained from sampling and will be used to develop regression relationships. Figure 2 shows the preliminary paired study data for all of the Commission monitoring sites. The best-fit chloride-specific conductance relationships will be used to estimate chloride concentrations based on the observed continuous specific conductance data. The study will transition into the analysis phase upon completion of data collection.
 

Presentations

11-9-22 Chloride Impact Study TAC meeting presentation

1-19-22 Chloride Impact Study Update presentation to WDNR staff

6-5-20 Chloride Impact Study Presentation at the Healthy Lakes Conference

3-29-19 Chloride Impact Study Update Presentation

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Meeting Materials

11-9-22 TAC Meeting Summary Notes

6-5-18 Summary Notes

10-21-15 Summary Notes

9-8-15 Summary Notes