Is It Clean?

The Connecticut River and its tributaries are much cleaner than they were decades ago.  The Clean Water Act, lots of money, and the hard work of many people have made this happen.  But, there are times - particularly after a rainfall event- when our rivers still might make you sick.  This website is designed to help you understand water quality patterns at sites you use for recreation.

The map on this page identifies locations tested for Escherichia coli (E. coli) bacteria levels during the monitoring season.  Click on the blue, yellow, or red flag icons to learn more about bacteria levels at that site and the associated group's monitoring work.  Or use the drop-down boxes to search by site name, town, state, water body or monitoring organization.

It is important to note that this information is a snapshot of river conditions at the moment the sample was taken. Please take the time to click through on the pins to look at the data. You will see when the last sample was taken and the historical data will illustrate that most often the site is only not clean after a major rain event. 

The monitoring season is typically from late May to October and each group monitors at different intervals and begin at different points in the season.  Be sure take the most recent sample date into account as well as patterns over time, and recent weather and flow conditions, when deciding whether to swim or paddle.

BLUEClean for swimming and boating<235 cfu/100 ml
YELLOWClean for boating only235 - 575 cfu/100 ml
REDNot clean for swimming or boating>575 cfu/100 ml
WHITEResults available – See Link 
GREYHistorical Data 

The different colored flags and bacteria count ranges represent different risk thresholds, which are based on the statistical chances of getting sick if you come in contact with water in these bacteria ranges.  Some bacteria, viruses, and other microorganisms (“pathogens”) can make you sick with stomach pains, rashes, breathing problems, diarrhea, or other intestinal problems.  We test for E. coli bacteria in the water as an indicator for all types of other pathogens or "bad guys."  For more detailed information about bacteria standards for primary and secondary contact click here

The data will show bacteria levels for each sampling date and also whether or not it was a wet weather event.  Wet weather is often defined as any day in which >0.1" of rain fell within the 48 hours preceding sample collection.  Some groups may define this differently.  Bacteria levels are typically elevated during and shortly after wet weather events, and good precautions to take include:

  • Avoid swimming right after a heavy rain
  • Avoid contact with the river downstream of a sewage outfall
  • Cover open cuts/use ear and nose plugs

In addition to health concerns, swimmers should also be mindful to only swim in areas that match their abilities and be aware of depths, obstructions and tidal influence in the mainstem of the Lower River.

The information on this page would not exist were it not for the many groups and their dedicated volunteers who contribute to this page. Thank you!

We wish you a fun and safe season!

Connecticut River Bacteria Monitoring Video

Field Guide to Visual Water Quality Indicators

Historical data coming soon! Until then, make a request via email obtain historical data by clicking here.



Red Not Clean for Boating or Swimming
Yellow Clean for Boating
Blue Clean for Boating and Swimming
White Results Available - See Link
Grey Historical Data