SEATTLE (AP) — Washington state’s most populous county is set to pay more than $5 million to settle a threatened lawsuit from the Suquamish Tribe over sewage spills that have overflowed from King County treatment plants into Puget Sound.

In 2020, the tribe filed an intent to sue the county, documenting almost a dozen times in 2018 and 2019 when untreated or improperly treated sewage overflowed into the Sound from the West Point Treatment Plant in Seattle.

The facility is the largest sewage treatment plant in Washington and the third largest on the West Coast. The discharges added up to more than 6 million gallons.

The settlement, agreed to earlier this year by the tribe and County Executive Dow Constantine, passed unanimously out of the Metropolitan King County Council’s environment committee Thursday, The Seattle Times reported.

It still must be approved by the full council, which could happen later in September.

The proposed settlement also includes timelines for about $600 million in improvements at the treatment plant. The new pipes, pumps and batteries and other power supplies to keep pumps running in case of a power outage — are intended to prevent overflows which have generally happened in foul weather or during a power failure.

“The settlement agreement comes with a really strict timeline and methods for holding us accountable,” Christie True, director of the county’s Department of Natural Resources and Parks, said. “It enables us to say we have to get it done by this deadline.”

About half of the $5 million settlement would be placed into a mitigation fund controlled by the tribe, while the other half would go toward a new environmental project chosen by the county, to be finished within five years. The county would also agree to pay $240,000 toward the tribe’s attorney fees.

The county and the tribe emphasized that they had worked for more than two years to reach an agreement and avoid litigation.

“The waters of Puget Sound and the entire Salish Sea are the Tribe’s most treasured resource,” Suquamish Chairman Leonard Forsman said in a statement Thursday. “We are obliged to protect these waters, not only for ourselves but for all who rely on them for work, subsistence, recreation, and cultural practices.”