road salt

Is a Low Salt Diet in Order for the White Clay? (Part 2)

Snowy, icy days can make us thankful for the salt applied to make our roads safer yet road salt has a less safe side for our waterways. When ice and snow melt, the salt goes with it, washing into our streams and groundwater.  As with people, streams are healthier on a low-salt diet as high salt concentrations can harm plants, fish and other wildlife.  And considering how easily salt can corrode our cars it’s not surprising that high salt levels can impact infrastructure including roads and pipes and municipal and industrial processes that use water from streams.

Road salt applied to parking lot.

Road salt applied to parking lot.

To understand the potential issues with road salt, volunteers and staff from the White Clay Wild and Scenic Program, Delaware Nature Society, and the Nature Conservancy have been monitoring our local streams. 

On Mill Creek - a tributary of White Clay Creek - in Hockessin, average conductivity (a measure related to the level of dissolved salts) have shown large spikes over the winter season as melting snow and rain have flushed salt into streams and groundwater. 


These high peaks – which correspond to winter rain & snow events – are not seen during other times of the year.

Larger spikes were also documented on Hurricane Run, a small stream near Talleyville DE, which flows into the Brandywine Creek.  The high spikes are probably correlated to snow melt and rain washing salt off the many roads and parking areas around Concord Pike that drain into Hurricane Run.  Chloride concentrations over 250 ppm can make water taste salty and levels over 800 ppm are harmful to aquatic life.

While there are no easy solutions to the road salt quandary, municipalities and homeowners can consider smart salting practices including: 

  • Consider using sand and alternate products for sidewalks and driveways
  • Reposition downspouts and snow piles so that water and melting snow isn’t refreezing on paved surfaces
  • Keep salt piles covered
  • Proper calibration of salting equipment and training programs for salt applicators

To learn more and get involved with other monitoring projects contact:

Is a Low Salt Diet in Order for the White Clay?

Snow plow (c) New Garden Township

It’s wintertime! Along with the cold, snow, and ice comes another element, less recognized as a pollutant, but becoming an increasing threat to water quality – salt. Every year salt is dumped in mass on roads and other paved surfaces to help de-ice and improve safety. Once applied to the ground it is then either caught in the snowmelt when temperatures return back above freezing, or it is brushed into the environment by the cars driving over it. Don’t be discouraged – there are several things we can do to reduce salt pollution and still keep our surroundings safe!

  1. Shovel early and as much as possible to minimize the need for deicers
  2. Consider using a salt brine (23.3% salt and water mixture) to minimize the amount of chlorides released. You can make your own by mixing 13 pounds of salt in 5 gallons of water. Mix until all the salt is dissolved. Add to a masonry sprayer (available at Lowes or Home Depot) and apply the liquid 1-2 hours before a storm. Be careful not to over apply and create a slippery condition!
  3. Sweep up any excess salt and reuse or dispose of it in the trash.
  4. Temperature matters. Below 15 degrees F salt is ineffective so try using an alternative to salt, like pine needles or sand for added traction on walkways.
  5. Refrain from using kitty litter, ashes, fertilizer or any product containing urea to deice. This adds both salts as well as other pollutants to the waterway.

Why is salt considered a pollutant?

(c)U.S. Geological Survey:photo by S Corsi

Road salt, most commonly comprised of chloride and sodium (or chloride and another substance), dissolves readily in fresh water releasing chlorides into the environment. Chlorides are a growing concern to water scientists because they don’t break down, and once they’re in a water body there are no biological processes to remove them. Natural Chloride concentrations in fresh water are between 1 and 100 ppm (parts per million), that’s at or less than 0.01%. Chlorides can be toxic to aquatic plants and animals when levels go above these natural background concentrations, and they can also remain in the soil where they accumulate and become toxic to terrestrial plants and animals.

Chlorides interfere with an organism’s ability to regulate levels of salt and other substances within their bodily fluids. The effects vary by species type and location, but animals such as frogs and amphibians who lay eggs in “vernal pools,” or isolated bodies of water, may be especially at risk, as those water sources have no way of flushing out excess chlorides. Additionally, salt concentrations tend to spike in early spring (with the thawing of ground and snowmelt) and summer (when evaporation exceeds precipitation thereby concentrating salt), two critical times of year for amphibian reproduction and development.

How are public safety and water quality being addressed?

Salt pollution is challenging to address. Public safety and safe road conditions are paramount concerns, but protecting water quality needs to be considered as well. There are steps that can help address environmental concerns while still allowing safe road conditions and many groups are working to implement them. For example, the City of Newark, as well as most of our local municipalities, keep salt supplies covered and out of the elements to protect it directly from weather which would otherwise carry these chemicals into nearby water bodies. Some municipalities, such as the City of Newark also adopt Snow and Ice Control Plans that base salt application on snowfall amount and temperature, as well as primary areas of safety concern.

The long-term effects of chloride are still under study; as is research to find the most environmentally sound way to ensure public safety. Until a better solution is discovered try using some of the tips listed earlier on your property to help lessen salts from entering our waterways!

Want to learn more about how we are making progress addressing public safety and water quality? Check out some of these resources:

Chloride and Our Water –Monitoring the Mix (video)

University of New Hampshire Road Salt Reduction

New Hampshire Department of Environmental Services Road Salt Reduction Initiative

Capitol Region Watershed District, MN – Snow Removal and Salting Tips

Star Tribune (MN) - Road salt use gets weighed against saving money, environment