Tainted water a mystery
Are apples the culprits?
Some Marlborough residents are worried that the orchards that once blanketed the city have left a toxic legacy, after recent tests found high levels of arsenic in one of the public water sources.
The finding prompted the city to shut down the water treatment plant at Milham Reservoir for a brief time until officials were assured that it screens for arsenic. Mayor Nancy Stevens reassured residents at a meeting last week that the drinking water is safe to drink.
But some in the Glen Street neighborhood still question whether construction of a restaurant nearby is disturbing dangerous chemicals. The restaurant site, like the neighborhood, formerly held orchards.
``They can build what they want , but protect my water," said Joanie O'Brien.
Identifying blame is not easy. Farmers sprayed fruit trees with arsenic-based pesticides to keep pests from invading their crops until the chemicals were banned nationally in 1988. Arsenic also occurs naturally -- sometimes in high concentrations -- in New England soil. Pinpointing the source has been a challenge for Ronald LaFreniere, Marlborough's public works commissioner.
``If there's anything we can conclude, and there's very little we can, it appears that the arsenic came in the reservoir through storm water as a result of heavy rainfall," LaFreniere said last week. ``That water can come from anywhere."
Officials first detected arsenic levels nearly two times federally allowed levels on June 28 after a massive thunderstorm.
Neighborhood residents have been monitoring construction of the 99 restaurant because testing of the soil there found arsenic, lead, and DDT.
O'Brien said after the thunderstorm, she saw runoff from the construction site flowing across Glen Street and into sewers. She took photos and called the mayor and her district city councilor. LaFreniere said he learned of the problem later the same night and had a chemist immediately test the water at Milham Brook and Milham Reservoir.
The results showed concentrations of arsenic that exceeded federal standards at two spots: Milham Brook as it enters Milham Reservoir and in the reservoir near the treatment plant intake pipe.
LaFreniere then shut down the plant for the short time it took to verify that the treatment process includes arsenic removal.
But a mystery remained. Lead and arsenic -- or lead arsenate -- were commonly mixed by farmers through the 1940s and sprayed on fruit trees to stop pests from ravaging crops. Routine water tests conducted by the city have never found excessive lead or DDT in the water supply.
``Based on the absence of lead in our tests, we concluded that the arsenic in the reservoir could not have come from" the 99 restaurant site, LaFreniere said. ``Our city specialist has reviewed the data as well and concluded the same thing."
Their finding does not sit well with O'Brien, who called the state's Executive Office of Environmental Affairs to complain. She said she was told that the matter should be handled by local officials because the site is not a state- monitored clean-up location. She said she is frustrated that local officials did not halt construction.
``We're banging our heads against the wall here," she said.
David Gadbois, a lawyer for the developer, the Gutierrez Co. of Burlington, disputed that the arsenic in the water was due to the construction work. Gadbois said repeated tests of city water -- paid for by the company -- have not shown heightened levels of contaminants. None of the tests showed the presence of DDT or lead in the water supply, he said, adding that those chemicals would likely accompany arsenic.
``I don't know how it got in the water supply, and I don't even hazard a guess," he said of the arsenic.
The consultant conducting the testing for the city did not return phone calls seeking a comment.
Francis Peryea , a soil scientist at the Tree Fruit Research & Extension Center at Washington State University, said arsenic from pesticides leaches into water more readily than lead. But Peryea noted that arsenic could come from any number of environmental sources. ``You can't know willy - nilly if it comes from pesticides or not," he said.
LaFreniere said the city would continue expanded water testing until work at the restaurant site is complete. He said the developer had corrected improper grading that contributed to the runoff following the June storm.
``The sooner this site gets stabilized," he said, ``the better off everybody is."
Megan Woolhouse can be called at 508-820-4236 or e-mailed at woolhouse@globe.com. 
