BINGHAM — Review of a proposed 62-turbine wind farm project has been put on hold in part because of concerns about bats that are being threatened by white-nose syndrome, a rapidly spreading fungal disease.

There is no estimated date for when the Bingham wind project might be approved by the state Department of Environmental Protection, said Dan Courtemanch, project manager for the Division of Land Resource Regulation Monday. A decision was originally expected this month, he said.

Bat mortality is a typical concern at wind energy farms and it is standard practice to evaluate bat habitats and mortality rates during project reviews. The Department of Environmental Protection, however, may be revising its recommendations on the turning speed of wind turbines, which can be a threat to birds and bats that fly into them, said Bob Stratton, supervisor of fisheries and wildlife support for the Department of Inland Fisheries and Wildlife. The department makes recommendations on how the Department of Environmental Protection, which gives final approval to wind projects, makes its decisions.

Birds and bats are more mobile at lower wind speeds, while at higher wind speeds they are more likely to hit turbines, said Stratton. One way of preventing the collisions is by reducing the speed at which turbines can spin, he said. What wind speeds should be in order to create the best conditions for birds and bats are being looked at not only in Maine, but also across the U.S., he said.

“There are a number of species of bats being negatively impacted by a variety of sources,” said Stratton.

Chief among them is white-nose syndrome, a disease characterized by abnormal behavior and a white fungus on the muzzle of the bat, that eventually leads to death and has been observed in Maine since 2011. It is bad enough that two bat species found in the Bingham area are currently being evaluated for listing under the Maine Endangered Species Act and also the U.S. Endangered Species Act, according to a study by the department. They are little brown bats and northern long-eared bats, according to a summary of the study released last month.

First Wind is working to address the concerns of the department regarding the protection of bat habitats, a spokesman said in an email on Monday.

“We remain hopeful the DEP will complete its review in an expeditious manner so that the region can realize the positive economic and environmental impacts of the Bingham project,” said First Wind spokesman John Lamontagne in an email Monday.

The DEP is working with First Wind to find a curtailment that is suitable to everyone involved in the application, said Courtemanch. Recommendations by the department are often incorporated into permit requirements, although they are not required to be, he said. Every wind project that has been approved in Maine has had to adhere to a curtailment, although there is no standard requirement for what that curtailment is, he said.

“We were surprised and disappointed by the department’s recommendation,” the company stated in a letter dated Oct.18.

It states that although the recommended change in curtailment may seem small, it will actually double the amount of renewable energy that is lost in order to protect the bat populations.

Previously, the department recommended that turbines not start spinning until wind reached a speed of five meters per second and they are now recommending a speed of six meters per second.

In addition to the recommended curtailment changes, the company has submitted additional information to their application including the potential to use a third model of turbine and to create buffer areas on all streams in the project area in order to protect spring salamander populations, according to documents filed with the application.

The DEP is reviewing the additional information and plans to schedule a second public hearing on the project in early 2014, said Courtemanch. At the first public hearing in July, residents of the area spoke for and against the project. Some said it would bring money to the area, while others said it posed a threat to the environment and rural character.

If approved, the project would be the largest wind farm in the state. First Wind operates five wind projects in Maine and originally filed their application for the Bingham project in May.

This story has been corrected.

Rachel Ohm— 612-2368 [email protected]