The Army has agreed to pay a $100,000 penalty for operating 12 large-capacity cesspools on Oahu and Hawaii island beyond a ban that went into effect on April 5, 2005, the U.S. Environmental Protection Agency announced Tuesday.

Large-capacity cesspools, which collect sanitary waste from toilets, sinks and other sources in the ground and allow it to percolate out the bottom, were banned because waste can enter groundwater and contaminate drinking water, the EPA said.

Cesspools are more widely used in Hawaii than in any other state in the country, according to the EPA.

The Army owned and operated the cesspools in Hawaii at three military facilities past the required closure date, according to a consent agreement. Four were at Wheeler Army Airfield/Schofield Barracks and have been closed. Six are at Pohakuloa Training Area and two at Kilauea Military Camp, both on Hawaii island.

Kilauea Military Camp is within the boundaries of Hawaii Volcanoes National Park.

The Army said it has been working closely with the EPA to address the 12 cesspools that were not in compliance with the Safe Drinking Water Act’s Underground Injection Control program.

In coordination with the EPA and state Health Department, the Army closed the four identified cesspools on Wheeler/Schofield between January 2015 and March 2016, officials said.

“We recognize that we were not in compliance, and we’re committed to doing better,” said Rhonda Suzuki, environmental division chief for U.S. Army Garrison-Hawaii. “Our focus is to close those remaining cesspools as quickly as possible.”

The Army said it has projects under way to close six of the eight identified large capacity cesspools on the island of Hawaii by the end of September. “Funding requests are being submitted to close the remaining two large-capacity cesspools on Hawaii; these projects are at the top of U.S. Army Garrison-Hawaii’s priority list, and staff have already started the project design process,” the Army said.