A plan by the Dukes County sheriff to build a 140-foot emergency services tower at the Oak Bluffs transfer station came before the Martha’s Vineyard Commission for review Thursday night.

At a public hearing, deputy sheriff Anthony Gould described the urgent need to upgrade the Island’s outmoded emergency services dispatch infrastructure.

“We are the only jurisdiction in the commonwealth that is on a VHF, analog system,” Mr. Gould told commissioners. “We’ve had serious coverage issues with this over the last 20 years and it poses a significant risk not only to our first responders, but to the public at large. The cracks in the system are starting to show.”

Under review by the commission as a development of regional impact, the proposed tower is the first step in a larger process to digitize the Island’s emergency services dispatch system, reduce its configuration down to five Islandwide sites and increase the system’s bandwidth from 136 to 174 megahertz. According to Mr. Gould, the increase would allow for 100 per cent street coverage on all of Martha’s Vineyard and the Elizabeth Islands with a low-powered, portable radio.

The current dispatch system has a “spoke and hub” layout, with a centralized tower at the sheriff’s office near the airport. If the centralized tower goes down, emergency services throughout the Island risk a loss in connectivity. The reconfigured five-tower system would create a backup loop between the proposed Oak Bluffs tower and existing towers off Christiantown Road in West Tisbury, at Peaked Hill in Chilmark, the sheriff’s office and the Verizon tower in Edgartown. The backup loop means that a power outage at one tower would not result in a loss in connectivity for the other four.

“This seems to be the best of all the tower stories we’ve heard over the past year,” said commissioner Trip Barnes. “I’m not even thinking about 911. I’m thinking about hurricanes and natural disasters and the ferry sinking.”

Dukes County sheriff Robert Ogden, who attended the meeting with Oak Bluffs police chief Erik Blake and fire chief John Rose, made it clear that the tower would be for the exclusive use of emergency services personnel.

“This is not a Verizon tower,” he said. “No private calls get routed through this tower.”

Emergency 911 calls go through traditional cell phone towers before they reach law enforcement and fire officials. The proposed tower is for the second step in the 911 call process, when emergency services dispatch the call throughout the Island at a different frequency than cellular devices.

After agreeing that the proposed tower posed no environmental concerns, commissioners discussed what they saw as two key issues: visibility and durability.

Simulated photogrpahs show that the tower would be visible from the ferry into Oak Bluffs and just barely visible driving eastward along certain spots of State Road.

“There’s not going be any lights on the top, no flashing lights?” asked commissioner Gail Barmakian. Sheriff Ogden said he couldn’t speak about potential lights on the tower until it clears approval with the Federal Aviation Administration.

“If there are lights, they’ll go directly upward,” he said.

Ms. Barmakian also asked about the tower’s ability to withstand heavy winds and storm gales. After commissioners initially closed the hearing, they decided to reopen it to receive testimony from a Motorola tower engineer who was in attendance. He promised that the tower would be built according to FEMA’s coastal construction guidelines, which differ depending on the height and type of tower. Because it is a lattice construction, not a monopole, the engineer estimated that the proposed tower would be able to withstand sustained wind speeds of 90 miles per hour and gusts as high as 110 miles per hour. The numbers could increase if regulators require greater durability, he said.

Commissioners closed the hearing for a second time, deciding to let the project go to the land use planning committee on Oct. 1 for deliberations and recommendations. A possible vote was set for Oct. 4, on condition that the tower conforms to FEMA safety standards.

Sheriff Ogden said his office has applied for a grant to fund the project, although he did not specify the amount.

“We have acquired a fiscal stream to make this part of the project happen,” the sheriff said. If the grant does not go through, Mr. Ogden said the town of Oak Bluffs has made room for the tower in their budget.

“It has to happen,” he said.

In other business, the commission voted to not require a public hearing for a change in use at Vineyard Youth Tennis, which plans to open up its facility off Barnes Road in Oak Bluffs for adult tennis and programming. With the benefactor for the unusual tennis program, which provides free instruction to Island children, bowing out after 20 years, leaders at the tennis center are plotting a new business strategy to support the program.

“We’re trying to make it more of a community facility,” Chris Scott, chairman of the board for Vineyard Youth Tennis, told commissioners. “It’s not only underutilized in the morning, it’s never utilized. By allowing adults to use the facility we can better service the 250 kids who take lessons there,” he said.

The modification allows adults to play from 8 a.m. to 2:30 p.m. and from 6:30 to 9:00 p.m. during the school year, and from 8 a.m. to 9 p.m. on a maximum of two courts during the summer. Mr. Scott assured commissioners that the changes would not affect youth tennis camps or other youth programming.

Youth tennis leaders also plan to rebuild the bubble over two of the facility’s courts that collapsed this past winter during a storm.

“Keep those balls in the air, kid,” commissioner Trip Barnes told Mr. Scott after the vote.