Heavy rains cause high E. coli levels

Category: News

Created on Thursday, 12 July 2007 06:57

Last Updated on Thursday, 12 July 2007 08:46

Published Date

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07/12/2007

A heavy rain fell throughout the Mad River Valley on Saturday night and Sunday, July 9, and 10, and is the likely contributor to high E. coli levels in many reaches of the watershed this week. Water samples taken by Friends of the Mad River volunteers on Monday morning, July 9, showed favorable swimming conditions in the middle reaches of the Mad River from the Lareau swim hole to the Meadow Road bridge, but equally unfavorable swimming conditions in Blueberry Lake, the upper reaches of the watershed in Warren, and the lower sections of the Mad River in Moretown down to the Winooski River.

Twenty-one of 37 sampling sites tested were in violation of Vermont's water quality standard of 77 colonies per 100 milliliters of water. The bacterial pollution developed as water levels in the low river were sharply increased by heavy rain causing a low and rising (LR) flow condition. Flow readings at the USGS gage in Moretown (http://waterdata.usgs.gov/nwis/uv/?&site_no=04288000) increased from a low of 34 cubic feet per second on Saturday, July 7, to a high of 158 cubic feet per second recorded on Monday, July 9, at the time of the Mad River Watch sampling.

With an increase in water flow like this, there is always a possibility of higher E. coli counts as bacteria is flushed into the brooks and streams and into the main stem of the Mad River.

"In most circumstances E. coli levels will begin to come back down until another rain event starts the cycle over, and it does look like we could get several more thunderstorms over the course of the next week. Swimmers should check the local weather forecasts before heading out to their favorite swimming hole. Our next testing date is July 23," said Friends of the Mad River watershed coordinator Miranda Lascaze.

For a complete list of test results, a helpful guide to understanding E. coli, or to report a river-related illness, check the Friends of the Mad River website www.FriendsoftheMadRiver.org, call 496-9127 or e-mail This email address is being protected from spambots. You need JavaScript enabled to view it. .

Thanks to this week's Mad River Watch volunteers Cyndee Button, Kirstin and Eleanor Reilly, Jack Byrne, Patti and Cyril Greene-Swift, Elizabeth Walker and Kinny Perot!