Monitoring Water Quality

The quality of the water in our rivers and streams is a reflection of the health of our entire watershed ecosystem. Land use practices and our changing climate can have a substantial impact on the quality of our water. Clean rivers are a must for healthy, sustainable human and wildlife populations, as well as for safe recreation and vibrant communities.

What do we study and why?

E. coli because this is a bacteria species that, when present in water at high levels, may cause illness making our waterways unsafe for recreation.

Dissolved oxygen (DO) because aquatic animals and plants need oxygen to survive. DO decreases as water warms. Higher DO levels usually indicate a healthy riverine ecosystem, and lower levels lead to degraded habitat.

Water temperature because it impacts the diversity of aquatic plant and animal life in our waterways. Warmer temperatures can reduce DO levels, increase salt concentrations, as well as toxicity of compounds such as insecticides.

Conductivity because this essentially indicates the concentration of salts (such as road salts) in the water which can negatively impact aquatic life.

View site-specific testing results for both current and previous years using our interactive tools.

How does our monitoring program work?

Once a month, April through October, teams of dedicated volunteers record stream conditions, collect on-site data, and obtain water samples for testing by lab volunteers. These teams allow NRWA to monitor dozens of sites along waterways throughout our watershed. The data is used by NRWA to identify hotspots to be further investigated and addressed. The data is also shared with Massachusetts Department of Environmental Protection and New Hampshire Department of Environmental Services.

In addition to the monthly volunteer monitoring, NRWA undertakes water testing to track bacterial levels at local swimming holes, with findings reported to local Boards of Health. NRWA also conducts bacterial source tracking to identify specific sources of pollution.

New nutrient sampling project

With funding from the Nashua, Squannacook, and Nissitissit Rivers Wild and Scenic Stewardship Council, the NRWA is launching a project to study nutrient levels in the Nashua River.The term nutrients in relation to water refers mainly to nitrogen and phosphorus which function as fertilizers when allowed to enter our rivers and streams. Nutrients cause excessive growth of vegetation such as algae and aquatic plants, including toxic algal blooms. This excess can cause a drop in the oxygen levels in water which negatively impacts aquatic life. Blocking of sunlight to native plants and creating impassable waterways are additional negative impacts of nutrient pollution. Nutrient pollution can be caused by fertilizer run-off from backyards, farms, and heavily paved areas, and can also come from discharge from wastewater treatment plants. In addition to sampling for nutrient levels in the river, NRWA is pursuing additional avenues to reduce the levels of nutrients entering our waterways.

In the 1960s, water in the North Nashua River changed color according to the color of paper being dyed on a given day.