(CNN) -- The U.S. government is getting its bill for the damage a Navy minesweeper did to a Philippine coral reef, and it's less than expected.
Philippine officials say the USS Guardian damaged 2,346 square meters (25,252 square feet) of Tubbataha Reef after it ran aground January 17. That's down from the original estimate of about 4,000 square meters (43,000 square feet).
And that means, under Philippine law, the United States owes $1.5 million in fines, the Tubbataha Protected Area Management Board said in a posting on the Tubbahata Reefs Natural Park website Monday.
The fines are based on the amount of reef that has been damaged, the state-run Philippine News Agency reported.
The Tubbahata board said the revised damage estimate was made by a team of U.S. Navy and Philippine marine biologists from Wednesday to Friday.
The original survey was conducted January 27 while the warship was still on the reef.
The Guardian was completely removed on March 30, when the ship's stern, the last of four sections into which its 224-foot-long hull had been cut, was lifted from the reef by a massive seagoing crane.
"Using aerial imaging, the grounding zone was originally outlined using the ship's length as the basis for computing the total damaged area. This image was later observed to be obliquely angled thus artificially expanding the area plotted on mapping software," the statement on the park's website said.
The cost of the salvage operation to remove the ship from the reef was $45 million, Stars and Stripes reported Monday, citing a U.S. 7th Fleet spokesman.
An investigation into the grounding is ongoing, but last week the Navy relieved the commanding officer and three members of the minesweeper's crew of their duties based on initial results of the probe, a Navy statement said.
"The initial investigation findings clearly indicate that the CO, Lt. Cmdr. Mark A. Rice; the executive officer (XO)/navigator, Lt. Daniel Tyler; the assistant navigator; and the officer of the deck at the time of the grounding did not adhere to standard U.S. Navy navigation procedures," the Navy statement said. "The U.S. Navy has the highest accountability standards, and all four Sailors were relieved by Rear Adm. Jeffrey Harley due to their role in the grounding and a loss of confidence."
Tubbahata Reef is a UNESCO World Heritage site that is home to about 500 species of fish and 350 species of coral as well as whales, dolphins, sharks, turtles and breeding seabirds.