The construction season has begun, yet a proposed wind farm in Mars Hill still hasn’t received its permits to place 33 turbines atop Mars Hill Mountain in Aroostook County.

The developer and town officials anticipating economic gains have been waiting as the Department of Environmental Protection seeks a solution to some biologists’ worries that the turbines could harm birds and other wildlife.

That wait could soon be over, a DEP spokeswoman said Wednesday.

The project’s developer, Evergreen Wind Power LLC, had initially expected to start construction soon after mud season and be producing electricity by November.

But two months ago, state and Maine Audubon biologists opposed the permit on the grounds that Evergreen had not sufficiently researched the effects on birds and bats. The area is not known to be a major migration route, but previous studies have indicated that more than 70 species of birds and bats may live or pass through the area.

The company argued that its modern turbines are designed to rotate more slowly and pose far less risk to birds than older models. However, DEP delayed granting the permit to resolve the issue. In recent weeks, both the Department of Inland Fisheries and Wildlife and Maine Audubon sent additional letters to the DEP.

Changing his department’s earlier position, DIF&W Commissioner Roland “Dan” Martin said in an April 23 letter that the developer should be granted the necessary permits so long as the company agrees to future research and other conditions.

However, a Maine Audubon biologist argued in a May 12 response, that although no permit should be approved without DIF&W’s conditions, Evergreen’s application won’t really be complete until studies on bird and bat populations -particularly during migration periods – are completed.

Data about the migration routes of birds and bats across inland landscapes just isn’t available, said Sally Stockwell of Maine Audubon.

“Since this is likely to be the first project to be sited [in Maine], we think it’s important to set the standard for the type of research we’d like to see before a project is approved,” Stockwell said.

DEP project manager Robin Clukey said Wednesday that she expects Commissioner Dawn Gallagher to rule on the permit within the next month. The project will most likely be approved, but with conditions, Clukey said.

The conditions proposed by DIF&W include the requirement that a $100,000 fund be set aside to fund spring and fall bird migration research using radar, as well as a two-year graduate research project to evaluate the effects of the turbines.

Also, the lighting at the site should conform to minimum Federal Aviation Administration standards, and the developer should agree to address any wildlife problems discovered during the research, Martin wrote.

Finally, Martin states that the Mars Hill project is not to be taken as precedent, and that future projects should require pre-construction studies.

Evergreen has not opposed the conditions. And Peter Gish, general counsel for Evergreen’s parent company, UPC Wind Partners, said Wednesday that the bird discussion has not altered the project’s timeline.

Rather, Gish worries that debate over a federal tax credit being considered by Congress might push the project into next year. The $68 million project’s financing hinges on approval of the tax credit, and although the Senate voted for the measure earlier this month, the House of Representatives may not take action until mid-summer. If the credit isn’t approved by next month, Evergreen could need an additional season to complete its construction work, he said.

“We’re starting to bump up against the time frame,” Gish said. “We’re keeping our fingers crossed.”