The Coast Guard cutter Kiska is scheduled to pull out of Hilo Harbor for good Saturday en route to its new home in Guam, leaving Hawaii island with only two Coast Guard personnel and prompting concern over how open-water searches and rescues there will be conducted.

Hawaii County Mayor Harry Kim said the Coast Guard notified county civil defense officials of the upcoming move, but he’s still waiting to hear the Coast Guard’s plan to cover the waters around the Big Island.

“We’re unsure of their backup plan,” Kim said. “They know, obviously, that they are responsible by law for all ocean-type search-and-rescues.”

County lifeguards and firefighters will continue to conduct nearshore searches and assist boaters in distress and fishermen who get swept out to sea. But Hawaii island has been relying on the Kiska for open-water search-and-rescue operations since it arrived in Hilo in 1990, Kim said.

“Our search (capability) in open water is very, very limited,” Kim said.

The Coast Guard has 18 people stationed in Hilo, but on Saturday the Kiska and its crew of two officers and 14 enlisted personnel are being sent to Guam to replace the cutter Assateague, which is being decommissioned.

“There will not be any helicopters (or) boats on the Big Island,” Coast Guard spokeswoman Petty Officer 3rd Class Amanda Levasseur wrote in an email to the Honolulu Star-Advertiser on Thursday.

The two remaining Coast Guardsmen from the Marine Safety Detachment are responsible for inspecting commercial vessels, responding to pollution reports, investigating marine casualties, managing waterways and licensing merchant mariners, Levasseur wrote.

“However, there is a constant ebb and flow of personnel to the Big Island from throughout the 14th (Coast Guard) District,” she said.

The redeployment of the Kiska is part of a larger effort to upgrade the fleet stationed in the 14th Coast Guard District, which covers Hawaii, Guam, American Samoa, some Pacific island nations and parts of Asia.

Three new bigger, 154-foot fast-response cutters costing $65 million each are scheduled to arrive on Sand Island on Oahu over the next two to three years to replace the aging fleet of 110-foot island-class cutters that includes the Kiska.

The fast-attack cutter Oliver Berry is scheduled to arrive this month, followed by the Joseph Gerczak sometime in fiscal 2018, Levasseur said.

The Coast Guard previously said that a third fast-response cutter, the William Hart, is expected in the fall of 2020. But Levasseur said Thursday the third fast-response cutter is expected in 2019 and has not been named.

All of the fast-response cutters are too long and deep to be berthed in Hilo, so they’ll be home-ported at Sand Island, where “we are able to keep the vessels better maintained and it is more economically efficient,” Levasseur wrote.

Asked how long it will take a fast-attack cutter to reach Hawaii island, Levasseur said in an email, “The travel time from Oahu to Big Island is irrelevant due to the fact we will continuously have assets patrolling through the Main Hawaiian Islands, much like all our cutters. If a search and rescue case were to arise, we would send whichever vessel was the closest for the quickest response possible.”

Levasseur said the fast-response cutters “are much faster, have better sea-keeping capability and will improve response times.”

Air Station Barbers Point also is home to three Coast Guard MH-65 Dolphin helicopters and four HC-130 airplanes. It takes a Dolphin about 90 minutes to reach Hawaii island from Oahu, and an HC-130 about 45 minutes, Levasseur said.

“Our Air assets are typically the first responders during search and rescue,” she wrote. “Even though a boat will not be permanently moored to the dock in Hilo, the community will see more Coast Guard presence with limited impact by the relocation of the Kiska.”

But none of the assurances by the Coast Guard seem to be compensating for the loss of a home-ported Coast Guard cutter that’s been patrolling Hawaii island waters over three decades.

“We’re definitely very concerned,” said Hawaii County Managing Director Wil Okabe. “The Kiska was definitely an opportunity to preserve a safe environment for people in need. It’s going to impact Hawaii island and the safety of the people on our island.”