The Navy said high surf conditions have forced it to suspend efforts to restabilize a coral reef damaged by the grounding of the USS Port Royal in February.

The Navy had already reattached nearly 5,400 coral colonies and removed 250 cubic yards of rubble at a cost of more than $7 million, according to a joint news release by the commander of the U.S. Pacific Fleet and the state Department of Land and Natural Resources.

However, high surf stalled the effort for 17 days, costing more than $600,000, and the Navy decided to halt the project. The Navy said it had covered nearly the entire affected area.

"The state appreciates the Navy's commitment to timely actions to remove rubble before onset of southerly summer swells which were critical to prevent further damage to the reef habitat," DLNR Chairwoman Laura H. Thielen said in the release. "However, any remaining rubble may cause additional damage to the reef and the surrounding areas. Once the summer swells have passed, future steps will involve identifying projects that can restore damaged reef and replace the loss of coral reef resources."

The Port Royal, a 9,600-ton guided missile cruiser, ran aground about a half-mile from the Honolulu International Airport's reef runway on the night of Feb. 5 and was freed on Feb. 9. The area damaged by the grounding is a complex "spur and groove" fringing reef with outcrops of coral interspersed with sandy areas, the DLNR said.

On March 30, the state notified the Navy that it intends to file a claim for damage to the reef and asked the Navy to perform emergency work to salvage surviving live coral and stabilize the reef to prevent surf-driven debris from causing additional damage.

The ship remains under repair at Pearl Harbor Naval Shipyard.

DLNR has previously reported that damage to the reef — "full of coral colonies some of which took hundreds of years to reach their present size" — covers an estimated six to 10 acres.

The Navy's repair effort was executed in four phases.

Divers first performed emergency work to move 73 rocks to deeper water and to reattach dozens of coral colonies. Contractors then assessed the grounding site to plan further repairs.

Coral collection and rubble removal were parts of the final two phases.

Rear Adm. Joseph Walsh, Pacific Fleet deputy commander, praised the effort.

"We were able to cover almost all of the affected area, reattaching almost 5,400 coral colonies," Walsh said in the release. "In addition, we removed enough rubble from the grounding site to prove the value of a new, environmentally friendly excavation process that was used by the contractors."