This article originally appeared on the Penn State Extension website with maps, photos and diagrams.
In 2023, members of the Little Lehigh Watershed Stewards heard about the issues related to road salt pollution and decided to study its effects in our watershed.
The Little Lehigh Watershed is composed of the Little Lehigh Creek to the south and east of Allentown and the Jordan Creek, which is to the north and feeds into the Little Lehigh in Allentown right before it flows into the Lehigh River.
The area has a variety of land use, including mountain areas to the north and south, agricultural areas, warehouse and industrial areas, suburban housing developments, and dense urban areas in Allentown.
With the help of Stroud Water Research Center, we designed a "salt snapshot" or synoptic sampling protocol, which we used to perform two studies in the summers of 2023 and 2024.
Selecting the Sampling Sites
We chose sampling sites that have a variety of land use and that were upstream and downstream of any sites like warehouses or housing developments that might cause salt pollution.
We made sure to include sites at headwater areas that are heavily forested to represent what are most likely the least contaminated conditions in the study region.
We also selected sites just upstream from the confluence of two tributaries to determine the effects of each tributary.
An important criterion for site selection was accessibility and safety for our volunteers, so most of the sites were in spots where there are publicly owned bridges over the creek where it is possible to collect samples without needing to go onto private property.
Timing of Testing
Our testing was done during the summer when most of the water in the streams was from groundwater, called base-flow conditions.
They were done at this time of year because, during the winter, there frequently are major temporary spikes in the amount of chloride in streams as a result of salty runoff events which can last anywhere from a few hours to several days.
While these fluctuations can be very harmful to aquatic wildlife, testing at these times does not give an accurate picture of how much chloride is in the groundwater and streams year-round.
Summertime testing, on the other hand, gives very compelling evidence of the year-round effects of salt pollution.
It is also important to do testing when the streams are at base-flow so that water samples are not diluted by rain.
In our area, we have some automated USGS stream monitoring stations that we utilized for stream flow data.
Another way to avoid rainfall influences is to wait 48 hours after the most recent rain event and then perform a visual inspection of local creeks.
Testing Day
On the day of testing, we had teams of two volunteers go out and collect the water samples during a three-hour time period.
Each team had a driver and a navigator who also collected the water samples.
The volunteers brought the water samples back to a central location, where they were later tested for chloride and conductivity.
Our Findings
In 2023, we tested 45 sites in the Little Lehigh Creek, and the following year, we added 45 more sites on the Jordan Creek.
In 2024, on the Little Lehigh, 28% of our samples were above 50 mg/l (the level for chronic toxicity threshold value for macro-invertebrates) and 54% were above 31 mg/l (unhealthy for people with hypertension).
As expected, the levels of chloride increased as the streams flowed through the more developed areas of the watershed, resulting in higher levels in Allentown and the warehouse district.
The Jordan Creek area is less developed, so as we suspected, we saw just 7% of samples that were over 50 mg/l; however, rather surprisingly, 41% were over 31 mg/l.
As a result of this study, we determined that there is chloride pollution in our watershed, and we identified problem areas where we need to focus our advocacy in the future.
If you would like to perform a salt snapshot study in your watershed, read more about our protocol: Salt Snapshot Protocol Guidance Manual.
What You Can Do to Reduce Road Salt Pollution at Home
Here are some steps you can take:
-- Shovel frequently so snow does not accumulate and turn to ice.
-- Salt works best on a thin layer of ice; always shovel any excess snow/ice before applying it.
-- Using more salt does not make snow and ice melt faster; it's not necessary to feel the crunch underfoot for the salt to be effective: one 12-ounce coffee mug of salt is sufficient for a 20-foot driveway or 10 sidewalk paving squares. The grains of salt should be about 3 inches apart.
-- Only apply salt in places where it is necessary.
-- After the storm, sweep up any excess salt and use it for the next time it snows.
-- You can also use alternatives to rock salt, such as sand, kitty litter, or birdseed.
-- If bad weather is forecast, cover small areas such as steps with a tarp to prevent snow accumulation.
-- Remember that it only takes one teaspoon of salt to pollute five gallons of water!
If you live in a controlled development that uses a private contractor, pay attention to how much road salt is being used, and if it appears to be excessive, bring it to the attention of your homeowners' association.
Click Here for the original article.
Visit the Master Watershed Stewards webpage to learn more about how you could become a Watershed Steward.
Visit the Penn State Extension website to learn more about many other educational opportunities.
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-- Green Roofs: Benefits And Design Considerations
-- Understanding Water Quality Issues With Roadside Springs
-- Register Now For Tree Planting Series Of Webinars Starting April 28
-- Penn State Extension Latest Ag Conservation Currents Newsletter
(Reprinted from the latest Penn State Extension Watershed Winds newsletter. Click Here to sign up for your own copy.)
Upcoming Extension Events
March 26-- Penn State Extension Pond Management Series (2 of 4). Noon to 1:00 p.m.
March 29-- Penn State Extension In-Person Rain Barrel Discovery Workshop, Lebanon County 11:00 to Noon
April 1-- Penn State Extension Hosts Private Water Supply Education & Water Testing Webinar; A Free Water Test Included. 6:30 to 7:30 p.m.
April 1-3-- Penn State ACAP Ag Conservation Con 2025 - Harrisburg
April 2-- Penn State Extension Pond Management Series (3 of 4). Noon to 1:00 p.m.
April 5-- Penn State Agriculture & Environment Center’s Greening The Lower Susquehanna Program Hosts n-Person Riparian Buffer Maintenance Workshop In Lancaster County 9:00 a.m. to Noon
April 8-- Penn State Extension (8 of 10) Pennsylvania Forests Webinar Seminar Series - Forest Resilience Scorecard for PA. Noon and 7:00 p.m.
April 9-- Penn State Extension Pond Management Series (4 of 4). Noon to 1:00 p.m.
April 21-- Penn State Extension In-Person Private Water Supply Education, Water Testing Workshop, Carlisle, Cumberland County, 6:30 to 7:30 p.m.
April 28, April 29-- Penn State Extension, PA Sea Grant In-Person Educator Workshops On Watershed Literacy & Tree Plantings In Lancaster County
April 29-- Penn State Center for Agricultural Conservation Assistance Training Hosts Webinar On Effective Outreach Engagement On Adopting Farm Conservation Practices 8:30 to 9:30 a.m.
May 6-7-- Pennsylvania Groundwater Symposium, Harrisburg
May 13-- Penn State Extension (9 of 10) Pennsylvania Forests Webinar Seminar Series - Tree Nuts in Pennsylvania. Noon and 7:00 p.m.
May 13-15-- Save the Date: DCNR Watershed Forestry Summit
June 10-- Penn State Extension (10 of 10) Pennsylvania Forests Webinar Seminar Series - The Use of Slash Walls to Exclude Deer and Regenerate Native Forest Tree Species. Noon and 7:00 p.m.
July 29 to Aug. 1-- Penn State Extension Hosts Soak Up Science - Be A Stream Doctor Day Camp For Youth 8-12 At The Southeast Agricultural Research Farm In Centre County [PaEN]
September 25-- Penn State Extension Dive Deeper Summit For Water Educators. Harrisburg.
Related Articles:
-- Master Watershed Stewards Expand Watershed-Friendly Residential Certification Program To Include New Residents; Over 400 Certified So Far [PaEN]
-- Little Lehigh Watershed Stewards: Monitoring Road Salt Pollution And Taking Action At Home [PaEN]
[Posted: March 24, 2025] PA Environment Digest
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