The state of Washington is on the hook for removing hundreds of fish barriers over the next 12 years following a June decision by the U.S. Supreme Court.

The ruling let a lower court’s decision stand, meaning the state will be responsible for replacing fish culverts that block salmon habitat. The state was sued in 2001 by 21 western Washington treaty tribes, which said state-owned barriers under highways that blocked fish passage were a violation of treaty rights. The case area includes all of Puget Sound and the Olympic Peninsula.

Since 1991, the state Department of Transportation and the Department of Fish and Wildlife have worked to eliminate fish barriers along state highways. Statewide, there are more than 3,700 fish-bearing highway crossings and nearly 2,000 present barriers to fish passage. By June 2017, the state had fixed 219 fish barrier passages but the Supreme Court ruling means the state will have to fix an additional 425 culverts by 2030 with an estimated price tag of $3.7 billion.

Washington State Department of Transportation biology branch manager Paul Wagner said the state Legislature has already allocated some $736 million to fix culverts but that the additional money will need to come from Olympia for the fixes.

“We’re not just waking up to this or starting work on it right now,” he said.

These high-priority culverts are ones that block access to more than 200 meters of upstream fish habitat. An additional 160 culverts, which block less than 200 meters, will also be fixed but there is no time limit for when they should be completed.

The culverts particularly harm native salmon populations, which has seen dramatic declines in Puget Sound for decades due to a complex mix of factors, including loss of habitat, climate change and pollution.

The decision was greeted by Lorraine Loomis, chair of the Northwest Indian Fisheries Commission, who issued a statement on the June 11 ruling.

“Today is a great day for salmon, tribes, treaty rights and everyone who lives in western Washington. This Supreme Court ruling means more salmon for everyone,” the statement said.

King County executive Dow Constantine also released a statement commending the court for ending the long-running lawsuit. The county has already been taking inventory of fish-blocking culverts on county roads.

“Now, it is the time to set aside acrimony and disagreement, and get to work reducing barriers to fish passage,” Constantine said.

However, state Attorney General Bob Ferguson said in a statement that many state-owned culverts are upstream from private, local or federal culverts that already impede fish passage. King County owns several thousand more culverts than the state, Ferguson said.

“It is unfortunate that Washington state taxpayers will be shouldering all the responsibility for the federal government’s faulty culvert design. The Legislature has a big responsibility in front of it to ensure the state meets its obligations under the court’s ruling,” Ferguson said in the release.

The ruling came days after the state Supreme Court ruled that the state had fulfilled its obligation to fully fund basic education in accordance with the McCleary Decision. The legislature this session passed a new salary model for employees, which in addition to a 2017 overhaul of the state’s funding system, brought the state into compliance by increasing a $1.8 billion increase in funds over two years.