The 9th Cirucit Court of Appleals has ruled that Washington state must repair road culverts that are blocking salmon from swimming to spawning areas because the pipes violate fishing rights protected by tribal treatie. The ruling is a major victory for 21 tribes joined by the U.S. government that sued Washington state in 2001, arguing that hundreds of culverts block salmon from more than 1,000 miles of streams in western Washington.

"The Indians did not understand the Treaties to promise that they would have access to their usual and accustomed fishing places, but with a qualification that would allow the government to diminish or destroy the fish runs," Judge William Fletcher, of the 9th U.S. Circuit Court of Appeals, wrote in a 59-page opinion on Monday.

Three judges unanimously affirmed a lower court's 2013 order that Washington state correct its road culverts because they violated the Stevens Treaties of 1854-55, the opinion says. Under the treaties, the tribes relinquished huge tracts of land in exchange for a guaranteed right to off-reservation fishing.

The lower court held that the culverts have caused the size of salmon runs in Washington state to diminish and therefore violated the state's obligations under the treaties, according to Monday's ruling.