The Tulalip Tribes have successfully transformed the Coho Creek drainage ditch in west Washington into a meandering stream teeming with salmon, since beginning restoration efforts in 2000, reported The Daily Herald.
"The numbers are varying quite a bit but they're going up," said Kurt Nelson, environmental division manager for the Tulalip Tribes.
The area lost its wild salmon when the U.S. Army leased it during World War II for munitions storage, then Boeing until 2001 for engine testing. Culverts were built, blocking fish from traveling upstream to spawn.
The Tulalip Tribes have spent about $1 million on dismantling culverts, widening the stream, changing its course, adding spawn-friendly gravel, and creating small ponds with logs.
The ditch, located behind Quil Ceda Village, now attracts as many as 50 coho and 1,500 chum salmon in a given year.
When the first culvert was removed in 2000, chum salmon quickly moved upstream to spawn. The creek bed, however, was still too sandy to hold the eggs, so the tribe added more gravel.
"Every time we put new gravel in there, you see fish using it," Nelson told The Daily Herald. "That shows just how limited the spawning habitat is."
Originally, the tribe aimed to attract Puget Sound coho, known as silver salmon, a "species of concern,” according to the National Oceanic and Atmospheric Administration. Nelson hopes 300 to 400 coho salmon will return to the stream yearly to spawn.