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749 Hopmeadow St.
Simsbury, CT 06070

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Bacteria in the Farmington River

In 2002, the CT Department of Environmental Protection (CT DEP) added a 20-mile section of the Farmington River – stretching from the Town of Farmington (where the River turns North) to Rainbow Dam in Windsor – to the state’s "list of impaired water bodies" for having elevated bacteria levels. Soon after, the Farmington River Watershed Association (FRWA) began investigations into the sources and potential remedies for this bacteria contamination throughout the Watershed.

The local health department serving the "watershed" towns of Avon, Barkhamsted, Canton, Colebrook, East Granby, Farmington, Granby, Hartland, New Hartford and Simsbury is the Farmington Valley Health District. Since the River is such a popular recreational resource, the District has conducted water sampling along the River for years.

In 2004, FRWA joined with the Farmington Valley Health District (FVHD) to monitor for bacteria in additional locations, and provide the results to the public. Read FVHD’s measurements of E. Coli in the Farmington River taken in 2004.

Although E. Coli is not safe in drinking water supplies at any levels, the current standards for "non-designated swimming areas" such as in the Farmington River are 410 CFU (colony forming units) per 100 milliliter water sample.  At higher levels, E. Coli in water is increasingly likely to make people sick if it is ingested. Review the fact sheet on E. Coli from the Connecticut Department of Public Health.

It’s Takes Effort to Keep the River Clean

Keeping the Farmington River clean and safe is the responsibility of all those that enjoy the River – the paddlers, tubers, fishermen, hikers, picnickers and residents should all have a hand in caring for this wonderful resource. The aesthetics and safety of the stream corridor is best preserved when all trash is properly disposed of after enjoying time next to, in or on the River. Not only is garbage unsightly, it also makes its way to rivers and streams resulting in reduced water quality. So we make a request to all river users, "When You Pack It In – Be sure to Pack It Out."

Who is Testing for Bacteria in the River?

The CT DEP conducts infrequent monitoring of bacteria in all of the rivers in the State. However, the FVHD, the FRWA, and the Farmington River Coordinating Committee (FRCC) have undertaken a focused bacteria-monitoring program utilizing volunteers to better understand what the bacteria levels are in the Farmington River. The data from the FRWA/FRCC water quality monitoring program at 15 sites along the Upper Farmington River and its key tributaries will be available on this site in the near future. For a description of these sites and the water quality parameters collected, please click here.

What is the Source of the Bacteria?

Naturally occurring bacteria are important to a healthy, functional aquatic ecosystem. Most bacteria encountered in nature are harmless to humans and play an important role as decomposers of organic matter. Decomposers break down dead plants and animals into nutrients that are released back into the ecosystem. Bacteria as "recyclers" of nutrients are vital to a healthy stream environment.

However, bacteria that grow in the intestines of mammals and birds and make their way to our waterways are the bacteria of concern. Whenever humans or animals interface with streams, either directly or just by living near a stream, there is increased likelihood that harmful bacteria will contaminate the water. It is difficult to pinpoint any one particular source of bacterial contamination since bacteria enter streams from a number of sources including:

  • Storm water runoff (may contain multiple sources of bacteria)
  • Wastewater treatment plant discharges
  • Wastewater overflows or inadequate treatment technology
  • Sewer line leaks
  • Trash
  • Failing septic systems
  • Wildlife
  • Birds – waterfowl in particular
  • Pet waste
  • Human waste
  • Farm animal waste

Bacteria are transported to the River via storm water, catch basins, sediment, runoff, discharges, and spills. Larger amounts of bacteria reach the river when surrounding lands are more highly developed or "urbanized."  Through ongoing monitoring efforts we hope to better understand the cause of elevated bacteria levels especially during and following rain events, and work toward reducing or keeping bacteria from entering the River.

How Much Bacteria is Too Much?

The CT DEP and the Department of Public Health currently use the bacteria E. coli as an indicator organism of sanitary quality in water. As the amount of bacteria in the water increases, the risk of getting sick from contact with the water also increases. The most common ailment resulting from exposure to heightened bacteria levels is gastroenteritis and other intestinal discomforts. For more information, read the CT DEP’ s PDF, Water Quality Criteria.

Is it Safe to Swim in the Farmington River?

Yes, but at your own educated risk. The Farmington River has no official, state "Designated Swimming" areas, but the reality is that multitudes of people flock to the River for recreational uses. Full body contact with water is what is expected at "Designated Swimming" areas, however other recreational activities have some level of contact with the water. Water quality testing is being performed by the FVHD throughout the recreational use time period at established swimming areas in the Farmington River Watershed.


  • The most consistently high levels of bacteria in the River have been recorded during and following rain events. During rain and/or snowmelt, the bacteria levels recorded in the River rise almost instantaneously and remain elevated for an unknown period of time. Since there are no actual designated swimming areas there can be no "Beach Closures" issued so there is no way of knowing when it’s safe to go back in the water. Staying out of the River for some length of time following rain is the best public health guidance we can offer to date. When the turbidity or murkiness of the water has lessened, this is probably another indication that bacteria levels are back within a safe range.
  • To avoid sickness when coming in contact with the river – keep the water away from your face or open wounds. Illness may occur if one comes in contact with or ingests water with high bacteria
  • It is important to be aware that wastewater treatment plants disinfect effluent to protect the sanitary quality of the water they discharge to the River between May 1 and October 1. Outside that time period there is no chlorination, ultraviolet radiation, or other treatment of the effluent for bacteria, so bacteria levels can be elevated.
  • Stay out of the water when you are sick, because you may share your germs with those who would like to remain healthy.
  • Take responsibility for the River you recreate in to keep it safe for yourself and many others.

See also: Stream Walks, Aquatic Insect Monitoring, Waste Water Monitoring, & What Can You Do?

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