The mostly fair and tranquil weather that we've seen this month has kept water quality at a high level at local swimming holes in Windham County.
However, the latest round of testing by the Southeastern Vermont Watershed Alliance's (SeVWA's) water quality monitoring program showed E. coli results well above the Vermont and EPA standard for swimming suitability: 235 E. coli per 100 milliliters of water.
The SeVWA said Aug. 14 test results likely were skewed by heavy rain in the 24 to 48 hours before testing.
“The results indicate that E. coli is probably entering the streams in runoff and other sources (such as faulty septic systems) from the surrounding terrain during significant rainfalls,” the SeVWA wrote last week.
“A general recommendation is that it is prudent to wait 24-48 hours after a significant rain event to swim in the affected waters.”
On the West River, E. coli levels at Milk House Meadows in Brattleboro jumped from 49 on July 31 to 649 on Aug. 14, while the swimming hole below the Dummerston Covered Bridge surged from 50 to 345, and the Brookline Bridge swimming hole climbed from 48 to 388. A sample from Londonderry below Mountain Marketplace showed the highest reading of all: 817.
Indian Love Call, on the Rock River in Newfane, went from 10 to 126, while Pikes Falls in Jamaica jumped from 21 to 140.
The Whetstone Brook behind the former site of the Brattleboro Food Co-op went from 771 on July 31 down to 261 on Aug. 14, while, further upstream by the Brattleboro Farmers' Market, a 155 reading was logged.
On the Williams River, Herricks Cove in Rockingham was the lowest, at 69, while Golden Hill Road in Rockingham was highest, at 649.
Every site on the Saxtons River exceeded the 235 standard: Sandy Beach in Westminster saw the highest reading at 1,120, and the two Saxtons River sites - below the wastewater treatment plant (614) and at Stickney Field (462) - were both sharply higher than two weeks earlier.
According to the SeVWA, the E. coli in the water may not directly cause illness after swimming, but its presence indicates that there is probable fecal contamination of the water by warm-blooded animals. Swimming in water with an E. coli level greater than 235 per 100 milliliters of water puts one at a higher probable risk of developing a waterborne illness.
The final test of the season takes place on Wednesday, Aug. 28. Results will be posted at bit.ly/1dfKDHx.