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Pomperaug River Watershed Coalition Shares Recent Bacteria Levels on Interactive Map

Bacteria Levels on Interactive Map

Summer months bring outdoor recreation including water-based activities like fishing, boating, and swimming; however, high bacteria levels in water can make it unsafe for such recreation. In 2019, Pomperaug River Watershed Coalition (PRWC) piloted a bacteria sampling program along the Pomperaug, Weekeeepeemee, and Nonnewaug Rivers after the need for more data was identified as a high priority action in the organizations recently completed Watershed Based Plan. Samples were collected monthly from May through September from 13 sites throughout the watershed and were assessed for Escherichia coli (E. coli) and nitrate. This season, with COVID-response safety protocols in place, PRWC has continued to collect water samples and increased the frequency to twice monthly.

“We are collecting these samples to help ensure safe recreation and to refine the extent of stream segments that CT Department of Energy and Environmental Protection has identified as not meeting the State’s Water Quality Standards,” explained Carol Haskins, PRWC Executive Director. “There are a few stream segments that were ranked as not meeting the requirements for safe recreation, but the data sets used in that determination were limited and are now a bit dated. Additional data is needed to better determine the extent of the ‘impairments’ and where pollutant and stormwater runoff reduction measures can be implemented.”

E. coli, a type of bacteria found abundantly in the gut of mammals including humans, is used as the primary sanitary indicator for fresh water. High bacteria levels can indicate water quality degradation from pollutant sources such as agricultural runoff, septic contamination, and pet waste. E. coli usually poses little concern to humans with the exception of one strain that is capable of causing illness. Prolonged exposure to or swallowing water containing high levels of E. coli can cause mild to severe symptoms that may present in a way similar to a stomach virus, an ear infection or a rash. Typical recovery is expected within a few days to over a week.

The safety of a stream for various forms of recreation is determined by the bacteria level. According to the State’s Water Quality Standards, areas designated for public swimming must be below 235 colony forming units / 100 mL (CFU/100mL). For non-designated swimming areas, that number rises to 410 CFU/mL. For other forms of recreation, like boating, a bacteria level below 575 CFU/mL is used as the guideline. Any bacteria level above 575 CFU/mL is deemed unsafe for recreation.

“For the most part, E. coli levels within the Pomperaug Watershed are measuring below the threshold for safe recreation” reported Hailey McKeever, PRWC Outreach Coordinator. “However, the levels usually go up after a rain event. So, a good rule of thumb is to wait at least 24 to 48 hours after a rain event for bacteria levels to come down again before wading in the river.”

While there are not any publicly designated swimming areas along the rivers and streams in the Pomperaug Watershed, nor are they ideal for canoeing or kayaking, people and pets do enjoy cooling off in the river on a hot summer day. The rivers are also a popular destination for anglers in the cooler spring and fall months. As such, PRWC plans to collect bacteria samples between April and October and is posting the most recent results online at www.

Results on the website are shown as part of a new interactive map with a red-light, yellow-light, green-light legend to indicate whether or not conditions are safe for recreation. With sampling occurring only twice a month, and the turnaround time from the lab, be sure to check the date for the results and if there has been any recent precipitation that would cause an increase in bacteria levels. Also note that the “safe/unsafe” designation is only based on the bacteria level and does not factor in water level, streamflow or substrate conditions. Rivers are inherently risky places to swim and boat due to their currents, uneven bottom, and often slippery substrate. One should always exercise caution around rivers.

In addition to bacteria and nitrate monitoring, PRWC monitors steam temperatures and conducts annual macroinvertebrate surveys. This year PRWC added conductivity to its stream assessment repertoire. Conductivity measures the presence of dissolved solids in the water with how well it passes an electrical current. The dissolved solids, such as nitrate, sulfate, chloride, phosphate, sodium, magnesium, calcium, iron, and aluminum, are essential for aquatic life, but like all things, are good in moderation. High conductivity could indicate human influences such as agricultural runoff or sewage, while much lower conductivity could indicate oil spills.

These stream assessments within the Pomperaug Watershed support comprehensive evaluation of the physical, chemical and biological characteristics of the watershed in relation to human health, ecological conditions, and designated water uses. In line with the Watershed Based Plan, the monitoring results help PRWC further characterize pollutant sources and problem areas, further bracket priority areas for non-point source pollution and stormwater runoff reduction projects, provide input for management tools such as models, and support scientifically-based decisions for preserving and improving the quality of our local water resources.

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