Nutrients

FRWA began monitoring nutrients in the watershed in 2025, with the first Watershed Nutrient Study which looked at wastewater treatment facilities and tributaries for inputs into the Farmington River, and subsequently Rainbow Reservoir.

Currently, FRWA monitors a total of 16 sites for nutrients in the watershed, 5 river sites and 11 tributaries with land uses indicative of nutrient pollution, such as agriculture, in relation to not just cyanobacteria blooms on Rainbow Reservoir, but conditions in Long Island Sound.

Sources of Nutrient Pollution

Nutrient pollution is an excess of nitrogen and phosphorus entering our waterways from natural or anthropogenic sources. While all life needs nutrients, too much will cause algae to grow more rapidly and form algal blooms, like the cyanobacteria blooms in Rainbow Reservoir in Windsor.

Nutrient pollution originates from both point sources and non point sources.

Point Sources

  • Water Pollution Treatment Facilities

  • Industrial Facilities

  • Concentrated Animal Feeding Operations

Non-Point Sources

  • Runoff from agricultural lands

What We Monitor

Our ongoing water quality monitoring provides information that complements the work of other agencies. It also builds up a long-term record that could show how the river responds to changes in the watershed.

Bacteria

Learn more about how we sample E. Coli to observe water quality in the watershed.

Chloride

Learn about monitoring road salt pollution in the watershed and how you can help.

Temperatures

Learn how and why FRWA monitors water temperature throughout the watershed.

Aquatic Insects

Learn how we sample macroinvertebrates to observe water quality in the watershed.

Cyanobacteria

Cyanobacteria and the FRWA studies of cyanobacteria blooms in Rainbow Reservoir.

Nutrients

Monitoring is done on Rainbow Reservoir in Windsor and on tributaries in our watershed.