Setting up another potential roadblock for the offshore wind farm proposed in Nantucket Sound, the town of Barnstable and two groups of Cape Cod citizens last week filed notices of intent to sue the state’s top environmental official for his endorsement of the project.

The three separate notices serve as formal appeals of the certificate signed last month by Massachusetts Secretary of Energy and Environmental Affairs Ian Bowles, who found that developers of the Cape Wind project had fulfilled their environmental review requirements on the state level. The actual lawsuits will commence in Barnstable Superior Court once any state or local agency grants a permit to the project.

Meanwhile, federal environmental review remains separate and ongoing.

The latest appeals come as little surprise for the controversial wind farm project, which has already faced a string of court battles since it was first proposed more than five years ago. A state environmental official this week dismissed the appeals as standard delay tactics by project opponents.

“The secretary has full confidence that the courts will uphold his decision,” said environmental affairs spokesman Robert Keough. “All of his decisions are grounded in well established environmental law.”

The Alliance to Protect Nantucket Sound, a well-funded Cape-based group that formed in opposition to the project, is one of the parties that filed an appeal last week.

It was joined by a separate group of Cape taxpayers represented by attorney John W. Spillane, who in 2002 filed an unsuccessful lawsuit challenging the installation of the Cape Wind data tower.

The notice of intent marks the first legal step that the town of Barnstable has taken against the project, though members of the town council publicly opposed the wind farm only weeks after it was proposed in November 2001.

Barnstable town attorney Robert D. Smith alleged in the filing last week that Secretary Bowles based his decision on a “biased, pre-conceived, politically-determined agenda.”

“The secretary’s palpable bias in favor of this project, and his issuance of the certificate, is evidenced by his willingness to ignore countless factual and legal inadequacies, misstatements, and the illogical and misleading conclusions of the proponent’s [environmental report],” Mr. Smith wrote.

Barbara Hill, executive director of Clean Power Now, a Cape-based advocacy group that favors the project, said she was disappointed that Barnstable town officials decided to appeal the state certificate.

“It’s going to show Barnstable to be a town that stuck its head in the sand,” said Ms. Hill, a Barnstable resident. “It’s horrifying to me that we’re such a close-minded people. Frankly, I’m embarrassed.”

Barnstable town manager John Klimm did not return a telephone call for comment yesterday.

Cape Wind developers are looking to build 130 wind turbines spread out over 25 square miles on Horseshoe Shoal. Supporters say the project would provide three quarters of the electricity needs of the Cape and Islands and serve as a symbolic step toward cleaner energy in this country, while opponents are concerned about aesthetic and navigation impacts, among other things.

The certificate signed by Secretary Bowles last month was seen as a huge win for project supporters. The decision cleared a major regulatory hurdle for Cape Wind developers, and allowed them to proceed with obtaining necessary permits from state and local agencies. Secretary Bowles also ruled that the project would provide significant benefits to air quality and energy reliability in New England.

In the notices filed last Friday and Saturday, the three organizations claimed that the certificate signed by Secretary Bowles was improper because it limited the scope of review to the electric transmission cables that fall within state jurisdiction, and did not fully address other impacts from the bulk of the project which is located in federal waters.

They argued that by not extending his jurisdiction over entire project, Secretary Bowles usurped the powers of those state and local agencies - including the Massachusetts Department of Environment Protection, the Cape Cod Commission, and town conservation commissions in Barnstable and Yarmouth - that now must use the certified report as their working reference document.

“The Secretary has abused his power, failed to exercise his appropriate authority . . . , intimidated his environmental agencies in their respective adjudicatory roles and as such, has committed reversible error, warranting judicial intervention,” wrote taxpayer attorney Mr. Spillane.

Secretary Bowles acknowledged in his certificate that he limited the scope of his review to state jurisdiction, and deferred more detailed and lengthy consideration of larger impacts from the overall project to the ongoing federal review.

The Minerals Management Service, the federal agency with lead regulatory authority over the project, was slated to issue its draft environmental report this spring, but announced earlier this month that it had postponed the release until late summer. A final permitting decision is not expected until fall 2008.

Depending on the timing of the state permits and the ensuing lawsuits, the appeals filed last week could result in further delay for the project.

Cape Wind spokesman Mark Rodgers offered only a short comment regarding the latest appeals.

“We’re confident that the commonwealth’s decision is correct,” he said.