Rain Causes Mad River E.coli Levels to Rise Considerably
Mad River Watch samplers braved wet weather to collect water samples at 36 sites on Monday morning. Steady rains began late Sunday and continued through Monday, causing the river flow in Moretown to rise to more than 400 cubic feet per second (cfs) at the time of sampling (historic average flow for June 29th is 86 cfs). The river continued to rise throughout the day, topping out near 900 cfs late Monday night.
Results from analysis of the water samples came in early Tuesday showing high E.coli levels at all sites, with all but two sites in violation of Vermont’s water quality standard. E.coli is an indicator of pollution from fecal matter (wildlife, human and or farm related), and an indicator of potential risks to swimmers due to the presence of pathogens. It is common for E.coli levels to spike as waters rise since rain washes pollutants into rivers. Downstream areas exhibit the highest E.coli levels due to the accumulation of wastes throughout the watershed. Mad River Watch analysis from June 29th follows this pattern, although the highest E.coli levels were found in tributaries: Folsom Brook, Pine Brook, High Bridge Brook and Welder Brook. This could be the result of the timing of sample collection, or from pollution inputs in those areas.
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While E.coli levels were high throughout the watershed on June 29th, samples taken during dry weather typically only show water quality violations at the downstream most sites. Mad River Watch data shows that E.coli levels decline as river levels also decline. These patterns are important to note: swimmers should take caution if recent rains have brought the river level up as this could mean rising E.coli levels.
For a full report of sampling results go to www.FriendsoftheMadRiver.org, or if you have questions about Mad River Watch call Friends of the Mad River Coordinator Caitrin Noel at 496-9127.
Many thanks to this week’s volunteers and staff: samplers - Elizabeth Walker, Susy Deane, Jonathon Goldhammer, Cathy & Barry Glick, Fran & Gary Plewak; posting results - Patti Greene-Swift; lab work - Cyndee Button.