The Maine Department of Environmental Protection has found that three wind turbines on Vinalhaven have exceeded nighttime noise limits and has asked Fox Islands Wind LLC to modify its operations.

The small island wind farm has proven controversial since it began operating a year ago, with some neighbors complaining of noise and other related problems. A group of neighbors has made two official complaints, and the DEP monitored the turbines in July.

According to a letter sent out Tuesday, the DEP found that the wind farm was producing noise levels of 47 decibels when it wasn’t supposed to exceed 45 decibels.

“The department views the compliance issues identified at this facility as a serious matter,” the DEP wrote.

The DEP wrote that the farm seems “likely to exceed” 45 decibels when there is “significant vertical and directional wind shear.” It directed Fox Islands Wind to submit a revised operational plan to ensure the windmills don’t exceed noise limits during those weather conditions.

George Baker, CEO of Fox Islands Wind, said a sound consultant who measured noise during the same period “absolutely doesn’t agree” that the evidence shows the farm is out of compliance. Using different methods for dealing with ambient noise, the consultant pegged the turbine sound level at 43 decibels, said Baker.

That said, “in the interest of being done with all of this,” Fox Islands Wind plans to install technology that automatically will slow the turbines down when the wind is out of the southwest with a very strong wind shear — where hard winds blow aloft with barely any breeze on the ground. That’s the condition DEP identified as problematic for noise, Baker said.

“What the letter says and what we intend to do is submit a revised operating protocol that takes care of this specified condition,” said Baker.

Cheryl Lindgren of the Fox Islands Wind Neighbors, a group upset with the wind farm, said residents were meeting with the DEP this morning, and she didn’t want to comment extensively ahead of that.

“We welcome any solutions that they can come up with, and we’ll look at them very carefully,” said Lindgren. “After a year, I’m very glad there is some movement on this.”

She said the DEP’s finding was “verification of what we’ve known for a whole year.” The DEP gave Fox Islands Wind until the end of January to submit a final operational plan. Lindgren said she preferred residents didn’t have to wait longer for action.

“As encouraged as I am by going one more step in this process, we would like to take a couple of steps and get this solved,” said Lindgren.

Baker said the weather conditions detailed by the DEP happen rarely and only in the summertime. In a Nov. 18 meeting with the agency, Fox Islands Wind was told by the state that if it didn’t fight efforts to slow down turbine speeds during those specific weather conditions then regulators would consider allowing the wind farm to exceed decibel levels during storms — when the noise on the ground from heavy wind was well above 45 decibels anyhow.

“If the DEP sticks to their word, we’ll generate more electricity than we do now,” said Baker.

The wind farm issue has generated interest both nationally and globally as the small island community struggles to balance the overall benefit to the community of lower power prices with the concerns of neighbors. It’s a scenario that’s being played out elsewhere in Maine, in rural communities across the state.

In 2008, members of the Fox Islands Electric Cooperative voted 382-5 in favor of the wind power plan with the goal of stabilizing or even reducing high power prices.

Baker said he didn’t want to minimize the concern, but noted that a small number of people are upset in an island community of 2,000 households.

“As a public policy matter, we have to figure out how we address these issues, and how we go forward with what I think are very important parts of our energy future in the face of some people who are very, very strongly opposed,” said Baker.

The issue is personal for neighbors to the wind farm. Lindgren’s husband, Arthur Lindgren, said the noise was “constant and it’s awful.”

“It’s ruined my property value — my house is worthless now; nobody would buy this,” he said.