Water Quality Monitoring

Water quality monitoring plays an important role in keeping our watershed residents informed about water quality issues and the overall health of our rivers. Our volunteers serve as “eyes” on the river, collecting chemical data but also observing changes in flow, turbidity, stream bank erosion, access challenges, etc.

Why do we monitor water quality?

This data contributes to a widespread, publicly-accessible database: The Vermont Integrated Watershed Information System
It provides supporting data for impaired stream listings or reclassification, DEC’s Wastewater Program, and control/impact monitoring for remediation sites.
It can prompt behavioral changes that improve water quality (ie. road salt, agricultural practices, etc)
Monitoring brings people out to our rivers which can lead to a more meaningful connection to our watershed

Which streams are monitored?

Friends of the Winooski River collects samples primarily in the capital area (Montpelier, Barre, Waterbury, Stowe) and the Winooski River headwaters (Cabot, Marshfield, Plainfield). You can find technical reports from these efforts on the right side of this page. Monitoring sites are on a 3-year cycle and can either be re-nominated for further sampling if necessary, or “retired” if the data shows there are no specific concerns.

Our community partners are monitoring other parts of the watershed:

Friends of the Mad River coordinates the Mad River Watch program, collecting data on swimming holes throughout their subwatershed of the Winooski: click here to learn more.

Winooski Natural Resources Conservation District manages the Rethink Runoff Stream Team, supporting outreach efforts for certain Chittenden County municipalities, including water quality monitoring: click here to learn more.

Which pollutants are monitored?

We monitor different parameters depending on the concerns that are associated with the location. There are a few basic resources that identify concerns across streams in Vermont, which can be a good starting point when thinking about monitoring. One is the biannual list of "Impaired Waters." Another, more specific to the Winooski watershed, is the Tactical Basin Plan for our basin (another word for watershed -- Winooski is Basin 8 in the State's system): click here to read the most recent TBP .

The most common pollutants of concern in the streams we sample are phosphorus, nitrogen, and chloride:

Phosphorus is a mineral nutrient that plants need to grow. It is a pollutant of concern in Lake Champlain, because high levels can result in algal blooms that discourage recreation and can become toxic. Algal blooms can also damage aquatic habitat when the decomposition of dead algae depletes the water of oxygen needed by fish and other aquatic life. Phosphorus sources include fertilizers, soil erosion, manure, pet and wildlife waste, wastewater, and organic matter. Since the goal for the Main Lake part of Lake Champlain is 10 ug per liter, streams with concentrations above 10 ug are considered as contributing sources to the lake.
Nitrogen has been of less concern in the Champlain Basin as it is not the limiting nutrient to algae blooms.The state indicates a water quality standard of 0.2-5mg/L NO3 depending on the class and elevation of the stream. This program monitors for Total Nitrogen which includes NO3. There is concern however that rising levels of Nitrogen will worsen the issue and have other environmental consequences. Due to remaining scientific uncertainty about the role of nitrogen in fresh waters, new numeric nitrogen criteria for Vermont have not been made. Nitrogen levels peak during storm events and fall during base flow.

Chloride levels above 230 mg/L in streams can lead to poor health and reduced reproduction of aquatic species, and also limit oxygen availability in lakes and ponds. Chloride sources include road deicing salts, wastewater, and leachate from landfills. Chloride levels have been rising in Lake Champlain, and it is important to monitor this chemical in the watershed, because once it is in the water, it is very expensive to remedy.

What about Escherichia coli (E. coli)?

Escerichia coli is a species of bacteria used as an indicator of fecal contamination (poop!) in rivers, streams, lakes, and oceans. While most strains of E. coli do not cause disease, they can be associated with other bacteria and viruses that do. The standard for E. coli is a geometric mean of 126 mpn/100mL. This corresponds to a level in which there is a probability that 32-36 humans out of 1000 would get sick from swallowing the water. The higher the level of E. coli in a stream, the higher the risk of a swimmer getting sick. Higher levels generally occur in the first 24-48 hours after it rains.

In 2024 and 2025, FWR partnered with Stone Environmental to measure E. coli in the Stevens Branch in from Williamstown to Montpelier. We collected water samples at regular intervals along the river, often downstream of bridge crossings and at confluences of major tributaries. Our first sampling event occurred in October of 2024 and included many samples over a large area; on later sampling dates, we narrowed the sampling locations to focus in on areas that had measured higher in earlier rounds. The Final Report of this study can be found here.

To see the results in a graphic form, check out this placard by MajaDesign. As you can see in the infographic, the Stevens Branch had lower levels of E. coli in Williamstown and Barre Town, levels that were generally safe for swimming. The picture changes as the river enters Barre City. We know that Barre City has aging infrastructure and quite a few known wastewater leaks to the river (the wastewater treatment facility also needs upgrading and better operations and maintenance practices -- our E. coli study was funded as part of the settlement of an enforcement action with the Agency of Natural Resources related to violations in the operation of the Barre wastewater plant). The levels of E. coli were very high through Barre City, and this bacterial contamination continues all the way to Montpelier.

Join our Volunteer Water Quality Monitoring team!

Want to get involved in a great hands-on project? Volunteers collect stream samples every other Tuesday from May to September (8 sampling events total). Our sampling window is typically 6:30-8:30 am. Volunteers bring water samples to a convenient location, and the FWR team delivers them to the Vermont Agriculture and Environmental Laboratory in Randolph to be analyzed.

Sampling takes about 15 minutes per site, and volunteers can collect samples from one or more sites. No experience necessary and training is provided annually at the start of the monitoring season.