Have you asked your town about a salt reduction plan?

March 24, 2025

OARS River Log | By Ben Wetherwill, OARS’ Water Quality Scientist | Published March 24, 2025

OARS has been monitoring chloride (salt) in our rivers for many years. Over the last few years, we have been raising a flag about the fact that chloride concentrations in the rivers are increasing at alarming rates. In freshwater systems, chloride can be toxic to fish and aquatic organisms. In groundwater drinking water wells, it can be harmful to human health. In previous articles, we have described how conductivity (which is very easy to measure) can be used as a proxy for chloride, and we have shared long-term data series showing conductivity increasing in all of our rivers. The graph below shows an example of the measurements OARS has taken in the Lower Assabet River since 2000, and it shows a very visible upward trend in conductivity.

Time series of specific conductivity (µS/cm) in the Lower Assabet River, 2000–2024

The solution to this issue is tricky. Chloride in the rivers primarily comes from road salt, and it seems unthinkable to consider halting road salting operations. There are also very few options for removing or capturing salt after it is applied, so practically all the road salt that is applied eventually makes its way to groundwater or rivers.

The best solution that we are aware of is controlling salt usage so that it is applied as efficiently and sparingly as possible. Each municipality should have a clear policy for reducing unnecessary salt application. We are particularly impressed with the Salt Reduction Plan developed for the Town of Lincoln. This plan clearly outlines salt tracking, formal Best Management Practices for managing salt, training, public education, designation of low salt areas, and facility modifications. The plan demonstrates how there are many procedures that can be implemented to more efficiently use salt, such as pretreatment, plowing prior to de-icing, monitoring of road temperatures, equipment calibration, and simple equipment cleaning. The Town of Lincoln estimated that these best management practices could help reduce salt application by more than 50%.

Please share Lincoln’s salt reduction plan with your town and ask them if they have a management plan for reducing salt application.

River Log

~30%

of the SuAsCo rivers watershed is wetlands, crucial for wildlife habitat and water quality

~30%

of water samples in the SuAsCo rivers watershed contain PFAS, leading to increased monitoring and remediation by local authorities and environmental groups

~70%

of dams in the SuAsCo watershed are over a century old, requiring extensive upkeep and presenting obstacles to river restoration and fish passage

>40%

of the land within the watershed is publicly accessible, offering recreational opportunities such as hiking, boating, and birdwatching to the community

~15%

of the land in the SuAsCo rivers watershed is covered by impervious surfaces such as roads, rooftops, and parking lots. This contributes to stormwater runoff and water pollution issues

>40%

of the land within the Sudbury, Assabet, and Concord rivers watershed is publicly accessible, providing endless opportunities for paddling, hiking, and wildlife exploration.

Have you asked your town about a salt reduction plan?

OARS River Log | By Ben Wetherwill, OARS’ Water Quality Scientist | Published March 24, 2025

Lincoln Salt Reduction Plan