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Working together for smarter winter maintenance and cleaner Pennsylvania waters
Researching chloride data for your watershed
To advocate effectively, it’s important to understand how road salt pollution is affecting your local waterways. The resources below can help you access data and visualize trends within your watershed.
1. Chloride Trend Graphs
Pennsylvania Road Salt Action volunteers are developing a growing library of graphs that display chloride levels in streams and rivers across the state, using data from USGS and EPA monitoring sites.
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Note: You will need to have PowerPoint installed to view these graphs.
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Click on this link to find chloride data graphs
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If your county is not yet listed, please contact us at paroadsaltactionwg@gmail.com and we will prioritize adding it to the list.
2. Water Utility Data
Contact your local water utility to find out if they collect data on chloride levels at their intakes. This can be graphed to show trends over time.
The graph below was created from data provided by the Lehigh Water Authority and shows a steady increase in chloride levels over the past 23 years at their intake on the Little Lehigh Creek in Allentown.
3. Conduct a "Salt Snapshot" Synoptic Study in Your Watershed
A “Salt Snapshot” is a coordinated sampling effort designed to measure chloride levels across a watershed during a short window of time—specifically when streams are at baseflow. Baseflow occurs after several days without rain when streamflow is supplied primarily by groundwater.
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Sampling during these dry periods (often in late summer or fall) provides a strong indication of year-round groundwater contamination, since road salt that infiltrates into groundwater continues to discharge into streams long after winter.
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To capture a clear picture of chloride sources and patterns:
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Choose sampling locations strategically. Include sites upstream and downstream of potential road-salt inputs such as major roads, parking lots, commercial areas, and housing developments.
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Add background reference sites. Forested headwaters, mountain areas, or otherwise undeveloped parts of the watershed help show natural chloride levels.​
Each water sample should be tested for chloride using test strips and for specific conductivity using a meter. Using both measurements provides helpful quality control and can highlight any unusual or inconsistent results.
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If you are interested in conducting a Salt Snapshot in your watershed, this Guidance Document from Stroud Water Research Center outlines all the steps you’ll need.
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For guidance in conducting a salt snapshot study or for science-related questions, contact Stroud Water Research Center:
4. Stroud Water Research Center Map.
In the fall of 2025, Stroud Water Research coordinated state-wide salt snapshot event where 700 volunteers collected about 1200 sampling locations. There was a second study completed in the winter of 2026. The results are displayed on the map on this page:
5. Participate in Izaak Walton League's Salt Watch
Salt Watch is an initiative of the Izaak Walton League. You can request a free salt watch kit that contains four test strips that can be used to test your waterway throughout the season. It also contains a chart to help you interpret your results and a postcard with instructions for completing the Salt Watch test and reporting your findings.
Salt Watch results are displayed on the Clean Water Hub, a collaborative tool to help people track water quality in local streams, lakes, and drinking water.
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For more information, click this link: https://iwla.org/salt-watch