Six of the 10 facilities in Hawaii that released the highest volumes of toxic chemicals into the environment in 2010 were in West Oahu, the U.S. Environmental Protection Agency said.

Hawaiian Electric Co.’s Kahe Generating Station topped the list with 550,651 pounds. Second was Joint Base Pearl Harbor-hickam with 420,761 pounds. Chevron’s refinery in Kapolei was third, and HECO’S Waiau power plant in Pearl City was fourth. Tesoro’s refinery and AES Hawaii’s power plant, both in Kapolei, were seventh and eighth, respectively. The 2010 data were self-reported by the facilities under a federal mandate and included in an annual report released Thursday by the U.S. Environmental Protection Agency. Thirty-seven facilities reported releasing 2.5 million pounds of toxic chemicals in Hawaii in 2010, a 15 percent drop from 2009, the EPA said. EPA spokesman Dean Higuchi said the release amount typically declines every year. Higuchi said the numbers are not a measurement of risk to human health and the environment. “It’s an information tool, first and foremost, to get people to know what’s in your neighborhood and to be aware of what potentially can be out there,” Higuchi said. State Rep. Karen Awana, who represents the district where the Kahe power plant is located, said the volume of emissions by the power plant is of concern, especially since her district also houses the island’s only municipal landfill and a construction-and-demolition landfill.

“It’s like our side of the island is bearing the brunt of the entire island,” Awana said. “It’s a tall order, and we just have to do our best to make sure the health and safety aspects are looked at closely.” She added that a Department of Health report last year cited no health risks from emissions in the area.

The EPA compiles data on the amounts of toxic chemicals released into the air, water or landfills; injected underground; and transferred off the site for disposal.

HECO spokesman Darren Pai said power plants are high on the list because there isn’t much heavy industry in the state to compare with.

He said the Kahe power plant, which uses low-sulfur fuel oil to power generators, had the highest volume of toxic release because it’s the state’s largest power plant. But the plant also released about 25 percent less toxic chemicals than in 2009. Pai said the decrease occurred because customers are using less energy and HECO is using fuel with a lower sulfur content.

“This sort of underscores the need for us to make more use of clean energy because by doing so it’s not only better for the economy, but it also helps to protect our environment,” he said.

As for residents around the power plant, Pai said HECO meets environmental compliance laws and tries to operate its units as efficiently as possible with the least amount of environmental impact. He added that Hawaii has consistently ranked as having some of the cleanest air in the country.

According to the EPA website, the Kahe plant released more than 99 percent of its toxic chemicals into the air, while Joint Base Pearl Harbor-hickam discharged most of its chemicals into the water.

The four other facilities in the top 10 were Maui Electric Co.’s power plants in Kahului and Maalaea, Hawaii Electric Light Co.’s power plant in Hilo and the Army’s Pohakuloa Training Area in Hilo.

U.S. Army Garrison Hawaii said the toxic release for Pohakuloa depends on the amount of training conducted and the type of ammunition used.

A U.S. Navy spokesman said nearly 90 percent of the Navy’s reported amounts are attributed to the release of nitrates, a byproduct of the Navy’s Wastewater Treatment Plant at Fort Kamehameha.