De-icing salts are among the biggest threats to local waterways. High salt levels after winter storms (or preparation for winter storms that never come) can kill fish and other aquatic wildlife. Salt in streams can impact human health as well. Filtering salt out of water is energy intensive, so salt from roads ends up in downstream drinking water supplies. In Philadelphia, directly downstream from many Lower Merion streams, salt levels in drinking water can reach problematic levels.

The Conservancy and our frequent partner Dr. Steven Goldsmith of the Department of Geography and the Environment at Villanova University have been tracking the impacts of road salt on streams for years. In a previous study, Dr. Goldsmith found that municipalities who use brine instead of rock salt reduce salt levels in streams by 20-40%.

Individual actions matter too. In the same study, salt from impervious surfaces on private and commercial properties (parking lots, driveways, sidewalks) accounted for as much or more of the salinity levels in streams than salt from roads.

Salt alternatives – whether in the form of a different de-icing substance, roads made of materials that could melt ice, or another developing technology – would be ideal solutions, but Dr. Goldsmith’s research shows that we can meaningfully lower salt levels in streams using existing technology and better practices. 

We recently received two grants from the National Fish and Wildlife Foundation to create change, going beyond our previous efforts. The project will involve stream monitoring, property owner surveys and cost-benefit analysis for municipalities converting from rock salt to brine. The monitoring equipment will stay in place to track salt levels over time. We will share updates as the project progresses.

Read more about how salt impacts streams below in the Salty Waters story map or in Dr. Goldsmith’s lecture.