Water Science and Restoration
PFAS and Other Hazards
PFAS, Mercury, HABs, RXs
Beyond the NRWA’s routine water monitoring program, attention is also given to additional sources of water contamination that can threaten the health of both humans and aquatic ecosystems. Some of these hazards are caused by pollutants from human sources and others are exacerbated by our changing climate.
PFAS
For decades, per- and polyfluoroalkyl substances (PFAS), a class of chemicals, have been used in industry and by manufacturers of consumer products. PFAS are commonly used in non-stick coatings, water and stain resistant materials, fire retardants, personal care products, and more. Two PFAS in particular, PFOA and PFOS, do not break down in the environment, allowing them to build up– on the land, in water, in the air, and in living things. Exposure to these “forever chemicals” can have detrimental effects on human health.
In our watershed, PFAS in drinking water supplies is an emerging issue with many communities identifying contaminated sources, both public supplies and private wells. Municipal officials are working to implement appropriate treatment methods and provide education materials to their residents. If you have concerns about your drinking water, you can contact your local Board of Health for information relevant to your community.
In the summer of 2024, the Massachusetts Department of Public Health issued a Public Health Advisory about PFAS contamination in fish in the Nashua River. Children and pregnant women are advised to avoid eating fish from the Nashua River, and other individuals are encouraged to limit their intake to one fish per month. NRWA works to spread this advisory to local Boards of Health, residents and recreational fishing groups from social media.
Mercury
Mercury is a toxic pollutant that has been spread around the world by industrial releases into our atmosphere which can travel for thousands of miles before returning to the earth. Mercury is deposited on our landscapes and waterways through rain and snow, dust particles settling on the land, and through runoff from polluted lands into our rivers and streams. After landing, this atmospheric mercury is converted naturally by microbes into a more toxic form called methylmercury. Levels of toxic mercury in any given area are influenced by a number of conditions. The concern is that methylmercury, when consumed, is easily absorbed by wildlife and humans. Additionally, those at the highest level of the food chain will have increased mercury exposure, biomagnification, because they are consuming lower levels species with mercury contamination. Mercury is know to have a significant impact on the health of fish, birds, other wildlife and pets, as well as humans.
The US Geologic Service (USGS) and the National Park Service (NPS) have partnered to study mercury levels across the United States through a citizen-science based project called the Dragonfly Mercury Project (DMP). It is known the dragonfly nymphs, which reside in water, are excellent bioindicators for mercury levels at their habitat site, meaning the level of mercury in a nymph reflects the level of mercury at that site. The Nashua, Squannacook, and Nissitissit Rivers Wild & Scenic Stewardship Council began participating in the DMP in 2022. Together with NPS staff, the NRWA provided volunteers, both staff and public, to collect nymph samples at three watershed locations, one on each Wild & Scenic River, the Nashua, Squannacook, and Nissitissit. The samples were returned to USGS for analysis and results will be reported through the USGS DMP Dashboard. USGS also creates a Dragon Flyer summarizing findings at each sampling site that can be shared with the public. USGS is also exploring the possibility that a similar sampling project could use dragonfly nymphs to determine PFAS levels at sampling sites.
Harmful Algal Blooms
While algae is a normal part of freshwater ecosystems, under certain circumstances some algaes can grow out of control, and a few produce toxins that are harmful or even fatal to wildlife, domestic animals, and humans. Such an occurrence is known as a Harmful Algal Bloom or HAB. Locally, HAB are caused by cyanobacteria or blue-green algae. Scientists believe the increase in HABs is caused by a number of factors including excess nutrients (like fertilizers) in the water and increasing water temperatures both of which encourage increased growth of algae. NRWA is initiating the process to study nutrient levels in our waterways as a first step to formulating a plan to reduce nutrient levels entering our rivers. Read more on our Water Monitoring page.
Blue-green algae can make the water appear like pea soup or paint. Exposure to this HAB is most dangerous when ingested. If you see a water body that appears to be impacted, it is important to contact your local public health department for further investigation. Do not allow your children to play in the water, and keep dogs and other pets safely away. Be sure to rinse off with fresh water when exposed. NRWA works with local communities to spread the word through social media if HABs are identified.
Pharmaceuticals
Medicines flushed down the drain or disposed of in our landfills can contaminate our lakes and streams, which can hurt fish and other aquatic wildlife, and may end up in our drinking water. Some medications, such as hormones and antidepressants, include endocrine disrupting compounds (EDCs), which interfere with the reproduction and normal growth of many aquatic species, such as frogs and fish. Wastewater treatment plants and septic systems are not currently designed to remove these contaminants.
The NRWA encourages everyone to dispose of unused pharmaceuticals (including veterinary medicines) safely at permanent drop boxes located throughout our watershed at most town public safety (or police) facilities. Additionally some pharmacies also maintain drop boxes. This service is free and anonymous. Unused drugs deposited at permanent drop box sites are properly disposed of through incineration thus reducing the amount of chemicals making their way to our waterways.
For a list of RX drop box locations in MA and NH, see the links in our Resources box below.