DENVER (AP) — Federal and state authorities reached a $3.5 million settlement with a Colorado energy company to resolve alleged violations of air quality laws, officials said.

Denver-based oil and gas producer KP Kauffman Company Inc. has agreed to pay $1 million and spend $2.5 million more improving pollution controls at 67 Colorado facilities, The Denver Post reports.

The settlement filed Tuesday in federal court was the fourth recent settlement with oil and gas companies in Colorado accused of violating laws designed to minimize air pollution from storage tanks.

Environmental Protection Agency inspectors and the state investigated Kauffman operations between 2013 and 2018 and found elevated hazardous emissions from tanks.

Leaks of chemicals called volatile organic compounds from industry facilities have been a focus of concern for air pollution control officials.

There are now compliance orders on 93% of 3,141 oil and gas industry facilities with storage tanks in the metro Denver area and parts of Weld County where air quality violates federal health standards, officials said.

The other settlements involved Noble Energy in 2015, PDC Energy in 2017 and HighPoint Operating Company in 2019.