Two down-Island town planning boards have come out strongly against a series of proposed changes to the Martha’s Vineyard Commission’s referral thresholds, arguing that stricter rules for reviewing subdivisions, residential building and commercial development are an unnecessary expansion of the commission’s authority.

An additional so-called big-house provision that would have allowed the commission to review individual large home developments as developments of regional impact (DRIs) has also been temporarily removed from the proposed checklist changes after town building inspectors, planning boards and the Martha’s Vineyard Builders Association voiced concerns about the bylaw earlier this year.

The commission — a unique regional planning agency with special powers to review development on the Island — is required to review and revise its so-called DRI checklist every two years. The checklist sets specific criteria, including thresholds for development referrals — and names the types of projects Island towns are required to refer to the commission for review.

The DRI checklist is up for review this year, and a commission subcommittee has been working on a set of proposed revisions for months.

At a public hearing Thursday night, subcommittee chairman Fred Hancock presented the thinking behind the proposed changes. As development has expanded on the Island, Mr. Hancock explained, the Island has experienced unprecedented threats to its sense of place, giving smaller projects broader significance.

“We wanted to take into account the character issue, which the committee felt is playing a larger and larger role in developments on the Island,” Mr. Hancock said. “And because of that, smaller projects will sometimes now take on a larger importance than they might have 10 or 20 years ago.”

The changes include lowering the review threshold for the subdivision of land from 10 lots to five lots for urban development, and from six lots to three lots for rural development. It also includes lowering the mixed-use exemption for commercial development from 2,000 square feet to 1,400 square feet, lowering the significant habitat threshold from two acres to one acre, and the lowering of the threshold for residential developments from 10 to five units.

The commission is also proposing an increase in the threshold for reviewing restaurants from 50 to 80 seats. And a placeholder clause for a future “big house” provision is temporarily on hold.

But broadly, the current changes will allow the commission to review slightly smaller projects that it couldn’t look at previously. Planning boards in Edgartown and Oak Bluffs have bristled at the proposed changes, saying their towns have adequate oversight tools for smaller developments.

In a letter sent to the commission that was referenced at the hearing Thursday, the chairmen of the two town planning boards said they had not been included in the checklist revision process and that the changes amount to overreach by the commission.

“We sincerely understand that there is a noble intent driving many of the proposed changes; however, many of the proposed changes to the DRI checklist appears to be less of an effort to protect Island interests, and more an unnecessary expansion of the commission’s authority over local development,” the letter said in part. “An expansion of the DRI checklist, simply to ‘capture’ development that might otherwise ‘escape’ DRI review, is not appropriate.”

The letter was signed by Mike McCourt, chairman of the Edgartown planning board, and T. Ewell Hopkins, chairman of the Oak Bluffs planning board.

The checklist changes have come up at various planning board meetings throughout the Island over the past months, at times sparking heated debate over the role and authority of the commission. Mr. Hancock has also presented the proposed changes to every town planning board and requested input and participation from members.

At the hearing Thursday, Island affordable housing advocates also expressed concern about the lower review thresholds for residential units and subdivisions.

Doug Ruskin, president of the board at Island Housing Trust, said towns allow IHT to go through an often complex four to eight-month purchase process because they believe in their mission. But an added review by the commission could test their willingness to support affordable housing.

“Patience has its limits,” Mr. Ruskin said. “And the checklist changes are sure to add many months to that contingency period, making such transactions more complex and likely unfeasible.”

But not everyone took issue with the checklist changes. In a letter, Virginia Jones, a longtime member of the West Tisbury planning board, said she believes the checklist should be strengthened, considering the threats facing the Vineyard. Ms. Jones said in the letter that her views were her own.

“We appreciate that there are concerns about the amount of time and money required to process applications,” she wrote. “However, as climate change, sea rise, and the loss of land diminish the amount of land for development (and the result in profound rises in value), if anything not only should the requirements and criteria been sharpened up, I feel that projects need to receive more, rather than less review and professional attention.”

Chairman Douglas Sederholm closed the hearing and left the written record open for one week. He said the committee would review concerns presented on Thursday before coming back to the commission with the full set of changes, and another public hearing could be held if needed.