The Public Service Board on Tuesday filed its final rule for wind turbine noise standards.
The board surprised a lot of people in March when the draft rules recommended what would be the lowest sound standards in the country for commercial wind projects.
Over the past few months the board held four public hearings, and collected hundreds of comments.
While the PSB did make some changes made, wind power advocates say the rules are still too restrictive.
"What the board has chosen to do here is functionally ban wind in Vermont," said Sarah Wolfe, a clean energy advocate with the Vermont Public Interest Research Group. "In a time where our planet and our state cannot afford to move backward, the board has chosen to ignore the evidence, in clear opposition to legislative intent and the good of Vermont."
The final rule keeps the daytime sound level at 42 decibels, but the board changed the allowable nighttime level from 35 decibels allowed in the draft rule to 39 decibels.
The board also kept a controversial setback limit of 10 times the height of the turbine, so that a 500-foot turbine would have to be at least 5,000 feet from the nearest residence.
But in the new rule the board does give developers an opportunity to apply for a waiver to the setback rule.
Wolfe says the changes are still not enough to encourage development.
"The board heard from hundreds of Vermonters urging them not to ban wind," Wolfe says. "This rule is out of touch with what Vermonters are asking for and it is unprecedented."
In filing its final rule the PSB also issued a 13-page letter, explaining why the changes were made and reacting to some of the comments.
In the letter the board members said they agreed that the original nighttime level of 35 decibels was too low.
"The board believes the two new levels strike the right balance," the three-member panel wrote. "The majority of the literature on the subject indicates that both the 42 dBA and 39 dBA levels are conservative for ensuring against direct health impacts from wind turbine sound."
The board also created a new category for very small wind projects which have fewer restrictions.
Annette Smith is director of Vermonters for a Clean Environment, an advocacy group that opposes industrial wind development.
Smith wanted the state to consider low frequency noise, which wasn't included in the final rule.
And she also says there should have been stricter limits set on how noise travels over property lines, and into houses with the windows open.
"This rule is an improvement over the standards that have been in place," she says. "The wind industry set up a huge hue and cry how this would shut down wind in Vermont, but it isn't true."
The new rule is a requirement of Vermont's energy siting law, which the Legislature passed in 2016.
Before these new rules were considered the PSB set sound standards on a case-by-case basis, and lawmakers wanted developers to have clear, consistent standards before proposing energy projects.
Addison County Senator Chris Bray is chairman of the Natural Resources and Energy Committee and helped write the energy siting law.
Bray said the sound rule was the most technical he has ever seen the state issue, and the Public Service Board did a thorough job putting the new standards together.
Bray is a strong supporter of renewable energy and he said he was willing to see how the rule plays out.
"Some say that it's too strict, and that it will result in a de facto moratorium for wind in Vermont, but I think it's too soon to tell whether that is so," he said. "We'll only know how well it fits Vermont as we move forward and start assessing projects that are proposed. I don't think it's fair to dismiss it out of hand as being restrictive. I don't know if we know that yet."
The rule now goes before the Legislative Committee on Administrative Rules for final approval.