Salt Testing
Urban streams like Little Falls Branch have it tough in the winter. As usual, the culprit is us. Because it's safer to have clear streets free of ice and snow, the people that plow the snow also put down salt – in huge quantities - often way more than is needed or even recommended by the State Highway Administration. As soon as things melt, much of that salt ends up in in the creek where it is toxic to the fresh water organisms. According to the WSSC, “it only takes one teaspoon of salt to pollute 5 gallons of water to a level that is toxic to fresh water ecosystems.”
To document the impact of road salt run-off, LFWA volunteers are taking water samples to see how high salt levels are in the creek and how they are affected by snow storms. This is a year-round program. We test before and after winter storms, but also every month so we can have baseline data.
Results
Salt Testing 2024-25 baseline results for December 2024. We’ll be doing baseline testing every month on the third weekend as well as testing after storm events. We are sampling at eight locations in the watershed on four creeks - the Little Falls Branch (5 sites), the Willett Branch (one site), the Glenbrook Tributary (one site), and the Minnehaha Branch (one site) as well as one site in Rock Creek. Missing bars indicate that no data was sampled from the location on that date.
Testing Site Locations (2024/5):
Protocol:
The Little Falls Watershed Alliance salt testing team participates in the Izaak Walton Winter Salt Watch and follows their instructions for testing. We test before and after winter storms (or whenever salt is applied) and once a month through out the rest of the year. Our results are shared on Clean Water Hub go into a national data base on for road salt testing. Learn about the Winter Salt Watch program HERE.
Updates
Where Does the Salt come from?
Salt spill on University Avenue in Northwest DC.
Have you ever wondered what happens to the salt that is spread on the sidewalks, driveways, and roads in our neighborhood during a winter storm? When it melts or is plowed off, the salt seeps into the groundwater or runs off into local streams and flows into the Potomac River.
what are the issues with too much salt?
While salt helps to melt or prevent the formation of ice and keep these surfaces safe, too much salt, also called chloride-based deicers, damages pavements and inhibits biological life in our streams. Salt is not biodegradable, accumulates over time, and has long-term corrosive effects and environmental impacts.
Harms aquatic animals and plants in local streams.
Pollutes soil and water
Damages buildings
Corrodes vehicles, pavement and pipes
Raises the salt levels of our drinking water (visit the WSSC website for a good discussion of this problem.)
Home owners can help reduce the impact of salt:
By limiting how much salt they use on their sidewalks and driveways. More is not better when it comes to salting. A 12-ounce coffee mug full of salt is enough to treat a 20-foot driveway or 10 sidewalk squares
By switching to magnesium chloride road salt. It continues to melt snow and ice until the temperature reaches -13 F. The salt releases 40% less chloride into the environment that either rock salt or calcium chloride.
By using a salt alternative – like kitty litter, sand or even a towel to cover slippery spots.
Remember: when the temperature of the pavement drops to below 15 degrees, salt won’t work
By reporting salt spills to 311. The County or DC Government will send someone out to clean them up. If they don’t, let your elected officials know.
Figure from From Izaak Walton League, Winter Salt Watch