2018-09-16 Coho Salmon Snohomish River Coho Salmon Snohomish River September 16, 2018 - November 15, 2018 Coho Salmon Snohomish River Coho Salmon opens September 16th on the Snohomish & Skykomish Rivers. Daily Limit 2. Min 12". This year the season ends November 15th.