What grows, lives in 4,000 tons of rock?
We will find out, as ConCom gives SBPF the green light to perform cobble mitigation study; Move seen as victory for beach nourishment project
BY PETER B. BRACE INDEPENDENT WRITER
By a vote of 4-1 on Feb. 13, the Conservation Commission closed the public hearing on the Siasconset Beach Preservation Fund's request to undertake a 12- month cobble habitat mitigation study off Quidnet Village.

The above graphic shows the test cobble habitat with the six plots and cobble density proposed for each grouping.

The vote is a positive step for the Siasconset Beach Preservation Fund, whose attorney and engineers will iron out conditions of the study with the ConCom at a meeting today.

Island charter and commercial fishermen requested the cobble mitigation study to see if SBPF's proposed replication of 105 acres of natural cobble habitat that its beach nourishment project is expected to erase could successfully assuage the loss of prime fishing grounds off Sankaty.

"As far as we're concerned, it's good for us," charter fishing captain Bob DeCosta said of the study. "We have plenty of soft, sandy, wavy bottom; we don't have much hard bottom. If the beach nourishment project gets permitted, down the road this will be another project you can quote for your mitigation project."

The SBPF proposal calls for three, one-acre plots of quarried cobble rock and concrete reef balls to be placed 400 to 600 feet offshore, with three more one-acre plots of rock and reef balls 1,000-1,200 feet off shore.

A total of 2,904 cubic yards of stone weighing 3,993 tons would be carefully deposited by barge in these areas over the course of seven days in early April. Once in place, Epsilon Associates, SBPF's primary coastal engineering firm, will monitor the artificial cobble habitat at intervals of three, six, nine and 12 months to determine if the marine vegetation and animals that grow in the natural cobble habitat off Sankaty will thrive in the pilot mitigation plots.

Although four commissioners felt SBPF had provided the required amount of data to issue an order of conditions for the project, ConCom member Dr. Sarah Oktay did not agree.

"I don't think we've been presented with enough information to adequately assess the impacts on the habitat, so I would not vote to close the public hearing," said Oktay. "I don't think there's enough data for us to evaluate this."

Specifically, Oktay said she needed more information on water current speeds, sand grain size and wave heights. She also needed to be assured that the pilot area will not smother current fish habitat with artificial reef and cobble. Several islanders in attendance at the meeting shared Oktay's feelings that SBPF did not know enough about the sandy bottom habitat off Quidnet to just plunk down nearly 4,000 tons of rock to see what grows on it and lives in it.

Ernie Steinauer, speaking as a citizen and plant ecologist for Mass. Audubon on Nantucket, stressed that the pilot mitigation project was an experiment that requires careful design and controls.

"It's to the benefit of the environment to have a very careful design and it's to the community's benefit to have a very careful design," said Steinauer. "I'm not saying this isn't a good project and that it shouldn't be permitted, but I just hope you condition it carefully."

But while DeCosta agreed with Oktay and ConCom member Andrew Bennett that dropping rocks on the bottom will change the benthic environment, he supported SBPF's findings and welcomed the 12-month study. He said he is fully aware of the dynamic, hardto track conditions on the bottom where the cobble plots will be placed.

"As far as I'm concerned, that habitat is being changed all the time," DeCosta said. "In that respect, I don't think it's that big of a deal. You're not going to chase anything out of there. I don't think you're going to find any fishermen that are against this; we're very interested to see what's going to happen down there."

The Conservation Commission will work on the order of conditions today at 4 p.m. in the Large Group Instruction room at Nantucket High School before

taking a vote. I