NORTH HAVEN — In an extraordinary step, the North Haven Select Board voted Sunday to ban visitors and seasonal residents immediately to prevent the spread of the coronavirus to the Penobscot Bay island.

The order approved by the board states that “people who do not reside on the island full time may not travel to the island due to the significant increase in risk associated with the transmission of COVID-19.”

Contractors who work on the island but do not live there may not travel to North Haven.

All travel to the island shall be limited to travel for “essential purposes,” the order said.

The island has an estimated year-round population of 355, but that swells significantly during the summer. The town held its annual town meeting on Saturday and concerns were voiced by some residents about the impact of seasonal residents arriving, possibly carrying the new coronavirus.

“Essential purposes” as defined by the emergency order means to receive or provide medical care, to provide direct care to people who reside on the island; to resupply bulk food items, fuel, and other products required for human consumption, habitation, and well-being; to conduct law enforcement activities, to fulfill Knox County, state, or federal obligations and to perform duties related to those obligations; and travel for other similar purposes associated with lifesaving, firefighting, and other activities related to the emergency care of persons or property.

Essential travel also includes travel to the mainland and back to North Haven Island for the purpose of obtaining groceries and other essential items.

North Haven is located 12 miles off Rockland and can be reached by daily trips by the Maine State Ferry Service from Rockland.

The town operates the North Haven Clinic, which is staffed by one nurse practitioner and is not licensed or operated as an emergency medical facility. Patients with serious emergency medical conditions, including patients with COVID-19 requiring hospitalization, must be taken to a mainland emergency medical facility by ambulance on a Maine State Ferry Service vessel.

Transporting patients who are potentially positive for the virus would leave the town without a nurse practitioner, without a lead emergency medical technician, and without its one ambulance for at least three hours, the Select Board stated in its order.

The town also has a limited supply of medical equipment, personal protective equipment, and medicine to treat potential patients.

The town has one grocery store – North Haven Grocery. J.O Brown’s operates the only gasoline pump and the only heating oil and kerosene oil truck on the island. GRM Plumbing and Heating operates the only propane gas delivery truck on North Haven. Penobscot Island Air is the only air carrier serving the island and is the town’s primary means of emergency medical transport.

The order also requires that anyone who has been in contact with someone with the virus must stay in their homes for at least 14 days, contact the medical center for advice, and contact the town office so food and needed supplies can be provided to them. Those who are quarantined are not to come to the medical center but contact the medical center and someone will respond in appropriate protective gear.

The board cited state laws as giving it the authority to take such action.

The town administrator, Rick Lattimer, is a former judge advocate general.