A new federal report says 125 concrete slabs accidentally landed on a live coral habitat in December during a state project to enhance an artificial reef off Keawakapu, Maui.

The state initially reported that it appeared about 50 slabs hit the reef.

A preliminary assessment performed by the U.S. Fish and Wildlife Service and the National Oceanic and Atmospheric Administration said the rest of the 1,400 modules weighing 2,800 pounds each landed on sand.

The report also said more study is needed to determine the "total injury" inflicted by the concrete slabs on the reef.

"Not all modules that landed on reef structure caused damage to coral colonies," the report said. "A few modules were balanced on the colonies underneath, creating a heavily shaded environment. Corals that are currently alive and shaded by the modules will likely undergo a certain level of mortality in any of the emergency response alternatives."

The report listed three restoration options, including no action, because any further movement of the modules from wave action is unlikely.

It says full removal could cause additional injury and towing could create a larger injury footprint. The report says selected modules could be extracted without further coral injury.

For a copy of the report, go to www.hawaii.gov/dlnr/dar/pdf/keawakapu.pdf.