Mad River Watch Results Show High E.coli during Recent Storm
By: friendv3 (friendv3) 2010.06.30

Click here to view results from 6/28/10


Mad River Watch samplers braved heavy rains and flooding insome locations to collect water samples at 36 sites on Monday morning. More than 2.5 inches of rain fell late Sunday into Monday morning, causing the river flow in Moretown to rise to more than 4,000 cubic feet per second (cfs) at the time of sampling (historicaverage flow for June 28th is 83 cfs).


Results from analysis of the water samples came in early Tuesday showing high E.coli levels at all sites, with all but one site (Clay Brook near Route 100) in violation of Vermont’s water quality standard (77 colonies E.coli per 100 ml water). In fact, many of the sites had more than 2,419 colonies of E.coli per 100 mL of water, which is the detection limit of the test.


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.colilevels due to the accumulation of wastes throughout the watershed. Mad River Watch analysis from June 28th follows this pattern.


While E.coli levels were high throughout the watershed on June 28th, samples taken throughout the watershed during dry weather typically only show water quality violations at the downstream most sites. Mad River Watch data shows that E.colilevels 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. If the water is high and brown, don’t go swimming. Once the river levels subside and the river runs clear again, Mad River Watch data trends show that E.coli levels will have typically declined as well.

Many thanks to this week’s volunteers and staff:

  • samplers - Elizabeth Walker, Susy Deane, Fran & Gary Plewak, Kate Sudhoff and Mike Ware
  • posting results - Patti Greene-Swift
  •  lab work -  Cyndee Button