The state Division of Aquatic Resources and a private company were fined $400,000 yesterday for dropping concrete blocks on a coral reef off Maui.

The Board of Land and Natural Resources decided the division should pay most of the fine — about $266,666 — for its role in the damage. The contractor, American Marine Corp., faces a $133,333 fine.

Land Board Chairwoman Laura Thielen said the division, which is part of the Department of Land and Natural Resources, failed to adequately assess the drop area before allowing American Marine to sink Z-shaped concrete blocks for an artificial reef habitat on Dec. 2.

Before the drop, state divers cleared a circle 100 yards wide for the artificial reef but did not find a coral reef outside the zone only 25 yards away, she said.

In addition, American Marine’s barge drifted as much as 300 to 400 feet from the drop zone buoy during the project, and division staff had to ask the contractor at least twice to reposition the barge, according to a report by DLNR.

The 1,452 concrete blocks were supposed to land on barren ocean floor, but 125 of them landed on a natural reef.

The Division of Aquatic Resources will begin a study to repair the reef and determine whether to leave the blocks because they are not causing further damage or remove them to help the reef heal faster, Thielen said. The division will report back to the board in about 60 days.

Thielen said the division could pay its fine by spending future funding or grants on reducing damage to coral reefs.

In a report submitted to the board, the department suggested a fine of about $824,373, but after three hours of discussion, the board settled on the lesser $400,000.

Thielen said she stopped the artificial reef program after the accident and notified a federal agency that the state must update its environmental impact statements before continuing to build artificial reefs.