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
Since January 10th-11th, we have tested at various sites on a limited basis due to extreme weather and icy conditions. The current average concentration levels, based on two or more readings at each site location, are shown in the chart below. Averages at several locations exceed the chronic threshold of 230 ppm, but it is anticipated that higher readings due to snow/ice melt will be observed at all site locations when we resume testing on February 12th.
Due to the frigid temperatures and lack of access to site locations, we have paused sampling until Thursday, February 12th.
To see how salt levels change before and after winter precipitation events, we sampled more frequently at various site locations following snow and/or icing. The readings for January 10th-11th indicate salt levels at various site locations were similar to the baseline readings reported on December 13th. Beginning on January 18th and continuing following the snow/ice storm on January 24th, we took readings at a few of the site locations that were accessible. The readings obtained during January into February are shown in the chart below.
2025-2026 Winter precipitation:
Snow Events: December 14, January 24
Data on precipitation in the area can be found at CoCoRaHS.org. The closest active station to Little Falls is MD-MG-145.
Testing Site Locations (2025/26):
We are sampling at 11 site locations in the watershed - Little Falls Branch (5 site locations), Willett Branch, Minnehana Branch, Glen Cove Tributary, Glenbrook Tributary, Spring Valley Tributary, and the source at Chevy Chase Village.
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 in the Creek come from?
The salt in the creek comes from excess road salt. The salt that is spread on the sidewalks, driveways, and roads in our neighborhood during a winter storm is the culprit. When the snow 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 than 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.
Salt spill on University Avenue in Northwest DC.
REport Salt Spills
Salt spills are pollution and illegal dumping. If you see huge or even little piles of salt, report it. The County or DC Government will send someone out to clean them up. If they don’t, let your elected officials know.
Montgomery County: Report spills in the county to 311 or online at https://www3.montgomerycountymd.gov/311/SolutionView.aspx...;
Montgomery Parks: Call Parks Customer Services at (301) 495-2595 or submit a report online at https://mocoparks.org/48vP974.
State Highways: can be reported to 1-800-543-2515
DC: call 311, report as illegal dumping or pollution.
Figure from From Izaak Walton League, Winter Salt Watch
RESOURCES
Montgomery County Winter Salt Wise
Metropolitan Washington Council of Governments Winter Salt Smart
Maryland Department of the Environment Winter Salts Slideshow
ALL results:
Winter 2024-2025 Report is HERE
Winter 2023-2024 Report is HERE
Winter 2022-2023 Report is HERE
Winter 2021-2022 Report is HERE
Winter 2020-2021 Report is HERE
Winter 2019 Report is HERE
Download data 2018-2021 HERE.