An increasing number of studies show that rock salt (sodium chloride) used to de-ice roads, parking lots and sidewalks can be toxic to fish, macro invertebrates and amphibians, prompting scientists …
An increasing number of studies show that rock salt (sodium chloride) used to de-ice roads, parking lots and sidewalks can be toxic to fish, macro invertebrates and amphibians, prompting scientists to take a closer look at a disturbing trend.
PA Fish & Boat Commission biologist Ben Lorson said, “Salinization is increasing across this nation. Even in areas where we weren’t expecting changes, we’re seeing increased salinity. It has been bumping up steadily over the past few decades. Although salt contamination may be more dramatic in winter, it can be present in fluctuating amounts throughout the year because salt gets stored in soil and released over time. It seeps into the aquifer and groundwater and once it is in a freshwater system, it can remain there indefinitely.”
Lorson went on to say, “Salt tolerance also varies among fish species. Rainbow trout fare better than brook trout, because rainbows have retained some ability to move from freshwater to saltier river estuaries. But in general, as salinity increases in a stream, diversity in the food web declines. You start to lose your most sensitive species. It’s seen with fish, mayflies, salamanders and mussels. It is believed that salinities can affect reproductive success since some early life stages like eggs & fry, may be more sensitive to increased salinity.”
Coordinator for PA’s Salt Watch program Emily Bialowas, who trains and equips volunteers to test streams monthly for salt contamination, had this to say, “We’re certainly in the forefront of being loud about road salt, the data we collect provides a snapshot of a significant problem that has been silently growing for years and years, and if we don’t change how we apply salt and how we think about it in connection with our watersheds, we are going to have an even bigger problem. We could put down so much less salt and our ability to get around would not change. A 12 ounce mug of salt should treat a 20-foot driveway. Yet convincing the public to reconsider how it uses salt is a huge challenge because of concerns about safety and liability.”
Biologist Lorson noted, “In each of the past five years Penn DOT applied about 850,000 tons of rock salt on highways across the state, or 500 pounds per lane mile, and another 8 million gallons of brine.”
Ryan Neuman, also a coordinator on the Salt Watch team said, “Besides recruiting Salt Watch volunteers for stream sampling, we work with the public to enlighten them about how anyone with a sidewalk or driveway can become part of the solution. We talk to neighbors, with homeowners and business owners, about cutting back on salt use. Public education is a big component.”
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