Wappinger Creek is a small creek that runs through upstate New York near the small town of Millbrook. Though the area surrounding Wappinger Creek is slightly more densely populated than the immediate area around the Dog River, Wappinger Creek remains rural enough to provide a close approximation for comparison to the conditions and dangers faced by the Dog river in Northfield. A recent report by the Cary Institute of Ecologic studies explored the dangers and pervasiveness of road salt as well as several possible solutions and mitigation techniques. As part of this study, data taken from Wappinger creek was analyzed to explore the effects and presence of road salt. The concentration of salt or salinity of the water as measured in milligrams per liter was found to increase steadily from 1988 until 2000 at which point the concentration became significantly more oscillatory. This can be more clearly seen in the following graph from the Cary Institute's report.
This graph shows several important data points, most are alarming are those plotted after 2002. These points raise concern because they are not only above the EPA's suggested 20 mg/L, but also because they cave trended, and continue to trend upwards. This continued increase in concentration suggests that while the amount of salt in the water is close to the aforementioned "safe" levels, it will likely continue to grow further from this benchmark and eventually into the directly harmful if not lethal range. However, long before these levels approach anything dangerous to humans, they will exceed the impact range for smaller organisms which depend on the river. Because relatively small increases in salinity can cause, browning in plants, a decreased ability to reproduce in amphibians, and lower the amount of nutrients available for plants, ecosystems can become compromised long before the salinity reaches "toxic" levels for even the smaller organisms.
Furthering this exploration of local groundwater, the Cleary Institute cited a 2008 study from Dutchess County New York which looked at 125 local wells. Of the 125 drinking water wells sampled, 48% had salt concentrations of 20 mg/L or greater. The study further reported that " high concentrations of sodium occur most commonly in shallow wells, in wells that are near point sources such as salt storage facilities, and in wells that are downhill from heavily salted roads" (Road Salt). These exposure concentrations suggest that the high number of "unsafe" wells due to excess salinity was likely not present before the recent road salt driven salt spike. To further explore the relative impact of road salt as compared to the dangers posed by other inputs such as sewage or storm water, the Cary institute compiled and published a pie chart to break down the contaminant sources for the Wappinger Creek.
Though the exact concentrations and sources of road salt may differ slightly in the Dog River, the frequency and severity of salt pollution in the Wappinger Creek demands that a broad spectrum study be conducted of the Dog River, especially where it abuts frequently salted roads. This study should be used to focus efforts to ensure that salinity levels remain safely below not only the recommended human consumption level but also bellow the concentrations at which it would become harmful to the watershed's ecosystem.
Works Cited:
Road Salt, Moving Towards The Solution https://www.caryinstitute.org/sites/default/files/public/downloads/report_road_salt.pdf