South Coast Air Quality Management District inspectors have issued a violation to a crude-oil tanker berthed in Long Beach for alleged fugitive emissions in an action aimed at identifying and mitigating elusive coastal odors, it was announced Friday.

“For the past two years we have devoted extensive resources to finding the sources of periodic foul odors in Long Beach, Seal Beach and Huntington Beach,” SCAQMD Executive Officer Wayne Nastri said.

“Using a combination of dedicated field staff, advanced emissions imaging technology, atmospheric modeling and in-house laboratory analysis, now for the first time we have confirmed one potential source of these odors,” he said.

On Tuesday, SCAQMD inspectors issued a Notice of Violation to GAC North America, the Long Beach-based shipping agent for the Nave Photon oil tanker. The two-million-barrel tanker is flagged in Hong Kong and transports crude oil from Middle Eastern countries to the U.S. West Coast, according to the air pollution agency.

SCAQMD inspectors allegedly found that seven of 10 inspected pressure release devices on the ship were leaking hydrocarbon vapors well in excess of limits in the agency’s Rule 1142—Marine Tank Vessel Operations. The leaks were documented with portable hydrocarbon detection devices as well as gas-imaging cameras, the agency said.

According to SCAQMD officials, representatives of Tesoro—the operator of the terminal where the ship was berthed—said they would contact the ship owner to ensure that leaking valves are repaired.

SCAQMD started tracking the ship on Oct. 26, when it received three complaints of petroleum-type odors in the Long Beach area. Based on the location of the ship in the Long Beach harbor, which was upwind of the complainants, as well as gas images captured by inspectors showing vapor leaks from the vessel, SCAQMD decided to follow up with an onboard inspection when the ship docked on Nov. 3 at Tesoro’s marine terminal, the agency said.

SCAQMD’s investigation is ongoing and inspectors are continuing to evaluate potential violations of other agency rules.

Since Jan. 1, 2016, SCAQMD has received more than 2,000 complaints from residents in Long Beach, Seal Beach and Huntington Beach of petroleum, sulfur and/or chemical-type odors. During these odor incidents, SCAQMD inspectors were not able to identify a source; however, an analysis of wind patterns strongly suggested an offshore source of the odors, according to the agency.