Casperkill Watershed Oral History Project

This winter has been one of the harshest in recent memory.  The battle to keep sidewalks, driveways, and roads cleared and safe for traveling has been raging for a few months now.

The following was adapted from Mary Ann Cunningham’s post on road salt at (http://www.dutchesswatersheds.org/research-topics/70-salting-the-earth)

Spreading salt on roads and walkways to reduce ice is a common practice, as it is relatively cheap and saves lives and property.  Road salt is effective because it lowers the freezing point of water, which causes the water to stay a liquid rather than freezing to ice.

Although it is important to have safe walking and driving conditions, excess road salt can have consequences for natural and built environments.  Excess salt:

• pollutes drinking water
• rusts cars, bicycles and bridges
• corrodes sidewalks, steps, and buildings
• harms invertebrates and nutrient-cycling bacteria in streams
• lowers biodiversity
• kills vegetation

In fact, “salting the earth” refers to the ancient practice of spreading salt on enemies’ fields to make them incapable of growing crops.

Salt use in the United States has risen from 0.16 million tons in 1940 to more than 23 million tons in 2005. In 2008, 71% of this was used for road de-icing, compared to only 5% for human consumption . This means that every year, we apply approximately 16 million tons of salt to roadways in the United States.

Although we often don’t think about it, all of this salt has to go somewhere. Salt enters streams when water from rain or melting snow washes it into stormdrains that lead directly to waterways (i.e. lakes, streams, rivers, or wetlands). Salty stormwater can also flow into pervious surfaces like soil, where salts can accumulate or flush through to groundwater systems. Salt in groundwater migrates slowly toward streams throughout the year, so that even during warmer months there are elevated levels of salt in the water.

Nearly all of the salt used on roadways is sodium chloride. While chloride can be naturally present in local streams in low amounts (through dissolution of bedrock), road salt is causing the levels of sodium and chloride to increase significantly, with potential consequences for the environment.”

For most of the year, chloride levels are below EPA water quality standards of 230 mg/L. However, during the winter months some streams exceed this. The Casperkill Creek is known to have among the highest chloride concentrations of all streams in Dutchess County. In winter, chloride concentrations in the Casperkill can exceed 1050 mg/L. These elevated levels are due to relatively high percentages of impervious surface cover (roads, parking lots, etc) where road salt is applied within the Casperkill watershed.

Reducing the amount of road salt applied during the winter would have many benefits: it would save money for municipalities, limit the wear on vehicles, and lessen the environmental impact. Unfortunately, road salt inputs are very difficult to reduce because it has proven to be an effective way to remove ice from paved surfaces and reduce the risk of accidents. We have come to expect clear and safe roads in all seasons, especially as commuting is important for many residents in the area and public transportation options are often limited.

Some small steps you can take to reduce the amount of road salt applied in your neighborhood include: encouraging your local department of transportation to require training sessions and possibly retrofit trucks with applicator regulators.  If you’re applying road salt to your driveway or walkway, be mindful of how much you use. Applying the salt as a briny liquid instead of a solid may also help improve its effectiveness.

Photo from recent road salt conference at Vassar College,  courtesy of Will Jobs.

For more information check out this report from the Cary Institute of Ecosystem Studies, which details how we can move towards a solution that reduces the amount of road salt that makes it into our local streams every year.

Photo of the Casperkill in winter from Anton Wellbrock, c. 1973.