7.12.10 MRW Results Show Lower E.coli
By: friendv3 (friendv3) 2010.07.27

go to table of results from 7.12.10

The third round of water samples taken by Friends of the Mad River volunteers on Monday morning July 12th show generally favorable swimming conditions with eight of thirty-six sites (22%) tested in violation of Vermontís water quality standards. The eight sites that were in violation of water quality standards were: Couple Club, Meadow Road bridge, North Road in Moretown, Moretown Village swim access, Ward Clapboard Mill, Welder Brook, Ward swimhole and Loverís Lane Bridge.  The state water quality standard for recreational waters measures E. coli bacteria, an indicator of pollution from human or animal waste and the potential presence of disease causing organisms.

E.coli levels throughout the watershed were much higher on the June 28th sampling date due to a rain event that washed pollution into the stream.  While a rainstorm two days before sampling on July 12th did bring the river level up significantly, both the river flow and E.coli level had declined by sampling time.   Increasingly favorable swimming conditions developed as water levels in the river declined:  after peaking at approximately 1,000 cubic feet per second (cfs) on Saturday morning, the volume of water flowing in the Mad River fell to approximately 160 cfs at the time of sampling on Monday morning.  This is higher than the median flow for this date (~70 cfs). 

Swimmers are more likely to encounter safe swimming conditions in declining flow since pollutants are not actively being washed into the river by rain; Mad River Watch historical data shows that typically when river flow declines, E.coli levels begin to decline as well.  Conversely, rising water levels mean rising E.coli levels, so be aware that when a rainstorm that turns the Mad Riverís waters brown with sediment there is also likely a rising risk to swimmers. 

For more information about E. coli and the Mad River Watch program, or to report a river-related illness call Friends of the Mad Rive at 496-9127.  Thanks to this weekís Mad River Watch volunteers: Elizabeth Walker, Michael Ware, Kate Sudhoff, Fran & Gary Plewak, Patti Greene Swift and Susy Deane.