Press Release

Citizen Scientists Track Road Salt Pollution Nationwide


Gaithersburg, MD – Although winter 2019-20 was mild across much of the country, Izaak Walton League volunteers found dangerous levels of road salt (sodium chloride) pollution in waterways nationwide. These citizen scientists are highlighting a water quality problem that threatens public health, fish and wildlife, and quality outdoor recreation experiences.

The Izaak Walton League created Winter Salt Watch to give volunteers the tools to identify excess road salt in streams and other waterways. This past winter, the League distributed test kits to about 1,000 volunteers who documented salt levels in streams across 19 states. The greatest numbers of test results received came from the Philadelphia, Minneapolis-St. Paul, DC, and Detroit regions.

High levels of chloride were found in streams around 10 metropolitan areas (see list below) – not just occasional spikes, but consistently high levels of chloride. How much is too much? Freshwater lakes and streams should have low to no salt content. Levels above 100 parts per million (ppm) are beyond what could be considered a naturally occurring concentration of salt. Moreover, according to the U.S. Environmental Protection Agency (EPA), concentrations above 230 ppm are toxic to aquatic life with prolonged exposure.

Of over 770 Salt Watch test results submitted from across the nation:

  • 28% yielded high readings (over 100 ppm)
  • 10% showed toxic levels (over 230 ppm)

More results from the Salt Watch campaign, including maps, can be found at

Road salt contamination is a water quality issue that researchers and government agencies around the country are trying to understand and solve, an effort that Salt Watch volunteers are contributing to. High salt levels in freshwater are dangerous to aquatic life, plant life, and potentially human health.

Having site-specific data on chloride levels is the first step in advocating for best practices to protect drivers and clean water. These best practices include:

  • Tailoring salt-application strategies based on the weather and the product being used. For example, certain road salts, such as sodium chloride, are only effective at ambient temperatures over 20 degrees. At lower temperatures, this product does not protect drivers and only exacerbates water pollution when weather gets warmer.
  • Using calibrated salt spreaders on salt trucks and road temperature sensors. Calibrated salt spreaders allow for a better understanding of how salt is being applied. Greater use of temperature sensors can dramatically reduce excess application of road salt before predicted storms. If road temperatures are above freezing, pre-treatment might not be necessary at all or the amount of salt applied can be dramatically reduced.
  • Training and certification for snowplow drivers and contractors who maintain walkways, parking lots, and service roads on private property. Testing by Salt Watch volunteers and the experience of state and local governments demonstrate that excessive salt application is common among private contractors, but simple training can quickly improve their practices.
  • Understanding how salt levels affect corrosion of drinking water pipes and how to prevent corrosion, which can increase levels of lead and other dangerous metals in drinking water.

As the months warm up, road salt pollution is still a concern for our country’s streams and rivers. Warm weather coupled with less streamflow means chloride levels will be even more concentrated, putting stress on wildlife and drinking water treatment plants. It is vital to decrease road salt application in the winter months, without sacrificing safety, to conserve water resources, protect wildlife, and maintain safe drinking water.

Visit for more information on this effort and to view maps of test results. More results from the Salt Watch campaign, including maps, can be found at Visit for details on state and local best management practices.

High chloride levels were documented in these 10 metropolitan areas: Washington, DC; Philadelphia, PA; Twin Cities, MN; Detroit, MI; St. Louis, MO; Kalamazoo, MI; Des Moines, IA; Erie, PA; Syracuse, NY; and La Crosse, WI.


Founded in 1922, the Izaak Walton League of America protects America's outdoors through education, community-based conservation, and promoting outdoor recreation.