WAILUKU — A preliminary report released by two federal agencies confirmed that when the state accidentally dropped 125, 1.3-ton concrete slabs onto a swath of coral reef last year, it damaged a living habitat for myriad fish and other aquatic life-forms.

The decades-old Keawakapu artificial reef is located in 60 to 120 feet of water about a half mile out from the border of Kihei and Wailea. On Dec. 2, the state Department of Land and Natural Resources was increasing the size of the South Maui reef by dropping 1,400 slabs onto what experts apparently thought was sand and areas of algae, according to a preliminary report issued last week by the U.S. Fish & Wildlife Service and National Oceanic and Atmospheric Administration.

What exactly the state should do to rectify the situation, if anything, remains undetermined. The report also did not spell out how much the three solutions presented would cost or who should foot the bill. But the agencies do say that the state should plan to restore the damaged coral.

The agencies' "Keawakapu Preliminary Injury Assessment," issued March 16, also did not delve into uncovering how the accident occurred or who is responsible.

More investigation is required to determine a variety of issues, such as the damage done to the underwater species and measuring the actual size of the live reef, according to the report.

The slabs hit live coral while the state's contractor, American Marine Corp., placed 1,400 of the concrete "modules" in a 5-acre area within the 52-acre Keawakapu artificial reef. The report did not say if state employees were onboard overseeing the operation.

The Keawakapu reef is made up of 150 cars, a sunken ship, 35 other concrete slabs and thousands of tires. The slabs that didn't hit the live coral landed safely on the sand or patches of algae, according to the report.

The report stated that because of the complexity of the habitat and location of the slabs, more study would be needed to determine the amount of damage done to live coral.

The reef-building technique of dropping slabs in coastal areas is used in regions across the United States to promote the growth of new live coral reef habitats, which spring up on their own on the man-made surfaces.

The state established the Keawakapu reef in 1962, and the project in December was the first addition to the artificial reef since 1990, according to the report.

Doing nothing to fix the problem might be the safest bet, since removing the slabs could result in further damage to the reef, the authors wrote.

However, the report also suggests conducting an emergency restoration project as well as a more thorough assessment of the damage and undergoing planning to bring back the lost underwater habitat.

The 17-page Keawakapu Preliminary Injury Assessment, which includes photos and maps, can be viewed online at www.hawaii.gov/dlnr/dar/pdf/keawakapu.pdf.

NOAA and Fish & Wildlife Service biologists independently conducted 14 survey dives over three days in early January. The surveys did not involve state aquatics officials to avoid any potential conflict of interest. Using global positioning systems and acoustic equipment, the biologists mapped, marked and measured the area and used digital photography to record the "reef injury" at the site, according to the report.

Some of the observations and recommendations from the report include: