BRATTLEBORO - Recent tests show unusually high levels of the potentially harmful E. coli bacteria in some local waterways, leaving officials and volunteers searching for answers.
In two spots - on Whetstone Brook in Brattleboro and Williams River in Chester - E. coli levels were more than eight times higher than state and national standards for suitable swimming.
But officials, while advising residents to be cautious, also say the data may have been skewed by heavy rains just before testing. Further tests, they say, may produce much different results.
"The population of E. coli can go up and down dramatically in a short period of time," said Erik Skarsten, a Southeastern Vermont Watershed Alliance board member.
The statistics come from June 13 samples collected by alliance volunteers and sent to a lab for analysis. It is the alliance's first such test this year, and officials say it also represents an important snapshot of how local rivers and streams were changed by Tropical Storm Irene's flooding in late August.
"This is a new baseline because of Irene," said Gloria Cristelli, the alliance's acting board president.
The organization, formerly known as West River Watershed Alliance, began monitoring water quality a decade ago. But the latest numbers have caused some concern: There were 17 sites with recorded data, and 11 exceeded governmental "swimming suitability" standards of 235 E. coli organisms per 100 milliliters of water.
Two sites tied for the worst: E. coli presence was measured at 1,987 per 100 milliliters in Whetstone Brook near Brattleboro Food Co-op and in Williams River in Chester at the Missing Link Bridge.
"Certainly, it is startling because they are so high," Skarsten said.
Other sites exceeded E. coli standards by smaller margins:
- West River: South Londonderry at Rowes Road (921 E. coli per 100 milliliters), South Londonderry above Route 100 bridge (921) and Londonderry below Mountain Marketplace (727).
- Rock River: Indian Love Call above Route 30 bridge (308).
- Saxtons River: Bellows Falls/Westminster "sandy beach" (771), Stickney's field swimming hole (436).
- Whetstone Brook: West Brattleboro at Dettman Drive (345).
E. coli is a found in fecal matter and can cause illness in humans. In a message accompanying the water-test findings, Laurie Callahan - the alliance's water quality monitoring program coordinator - said encountering E. coli in excess of governmental standards "puts you at a higher probable risk to develop some sort of waterborne illness."
It is unclear whether such levels have been sustained since June 13. Another round of tests is scheduled for Wednesday.
Officials noted that there had been heavy rainfall 18 to 24 hours before the tests, and Callahan wrote that "E. coli is probably entering the streams in runoff from the surrounding terrain during significant rainfalls.
"Various sources recommend that in that situation it is probably best to wait 24-48 hours after the significant rain to swim in the affected waters," Callahan wrote.
It's not yet clear where the E. coli contamination is coming from, though officials said they'll look into that. Skarsten said farm runoff and septic contamination are common sources.
That leads Cristelli to speculate about storm-related causes.
"Right now, we're concerned because there still could be septic systems that were damaged in Irene," she said.
More-frequent testing and analysis could provide a clearer picture of E. coli trends, but that's not feasible for the volunteer alliance.
"It would be nice if we could test every day," Skarsten said. "The reason we can only test on certain days is because of the money factor."
In fact, there's no guarantee that the alliance can continue water testing without additional assistance. Cristelli estimated that the group needs another $10,000 just for this year's activities.
Manpower also is a concern.
"We're looking for board members," Skarsten said. "And we're looking for volunteers for various activities - for example, education, administrative and grant writing."
Anyone who is interested can get in touch with the alliance through its website, https://sites.google.com/site/vtsevwa. Skarsten said finding additional assistance is critical.
"We need help - volunteers and money - to keep this program going," he said.
Mike Faher can be reached at firstname.lastname@example.org or 802-254-2311, ext. 275.