JUNEAU — A federal fisheries agency has raised concerns about the accuracy of some studies being conducted for a massive proposed dam in south-central Alaska.

In a letter to the project manager for the Susitna-Watana dam, the regional administrator of the National Marine Fisheries Service, James Balsiger, said for his agency to effectively review the project, studies must accurately identify fish species, develop accurate habitat models, and use the best available science to understand fish distribution and habitats. He said accurate information also is needed to integrate models without amplifying errors.

“Given the current issues with the data, it is not plausible that the data for predictive modeling be used to describe baseline conditions or to predict potential impacts,” he wrote. Requests for another year of studies cannot be approved given the current issues with the data, he wrote.

Similar concerns were raised by the Anchorage field supervisor for the U.S. Fish and Wildlife Service.

Project spokeswoman Emily Ford said that overall, the Alaska Energy Authority, which is pursuing the project, is confident in the information it is gathering.

She said the comments raised by agencies and others will be discussed during an upcoming round of technical meetings, at which the authority also will discuss its plans for next year. She said the authority is finding many similarities between the information it is gathering and that was gathered in the 1980s, when the project was last pursued, and is not seeing any large potential issues that need to be addressed.

The project, as envisioned, would feature a 735-foot high dam — higher than the Hoover Dam — built into the Susitna River Canyon. The project website says the dam would provide a source of long-term stable power and generate half of the Railbelt’s current electric demand. The Railbelt is the most populous region in Alaska.

But critics question the cost and see it as unnecessary with the state also pursuing a major natural gas pipeline project.

The Susitna River Coalition says the dam would hurt salmon runs, harm wildlife habitat and turn seasonal river flows upside down.

The coalition’s president, Mike Wood, said he’s worried the authority is rushing through the study phase to meet a 2016 target for filing a licensing application. He also questioned whether the quality of the data is worth the money that’s been spent so far, nearly $200 million.

Online:

Susitna-Watana project website: http://www.susitna-watanahydro.org/

Susitna River Coalition: http://susitnarivercoalition.org/