This fall only the lower river opens
The Snohomish normally opens on September 26 from the mouth all the way up to Monroe. In 2026 it will not. On September 22 WDFW issued an emergency rule closing all fishing from the railroad bridge upstream of the Lincoln Avenue boat launch, southeast of the town of Snohomish, up to the confluence of the Skykomish and Snoqualmie, from September 26 through November 1. The reason given is budget: cuts to monitoring money for the Skagit, Stillaguamish and Snohomish mean WDFW can only check enough anglers on a smaller stretch of river.
Everything downstream of that railroad bridge opens on September 26 as scheduled. The upper reach should reopen under permanent rules on November 2, but emergency rules change quickly in this basin; check the WDFW emergency rules page (wdfw.wa.gov/fishing/regulations/emergency-rules) the night before you go. This page reflects the rules posted there as of September 24, 2026.
Monroe to Port Gardner Bay
The river is short. It forms just west of Monroe where the Skykomish and Snoqualmie meet, runs northwest under State Route 522 and past Lord Hill Regional Park, and reaches downtown Snohomish, where the Pilchuck River comes in and State Route 9 crosses. From there it spreads through a broad floodplain along the east side of Everett into a delta of islands, sloughs and tideflats crossed by US 2, Interstate 5 and State Route 529, and empties into Possession Sound between Everett and Marysville. In November 2024 Everett voters approved legal rights for the river inside city limits, letting residents sue on its behalf.
For the coho season that geography gives you two kinds of water: the channel from the Lincoln Avenue launch down through Snohomish, and the slower delta water around Everett, where the rules include every channel, slough and connected waterway but not the tributaries.
Two reaches, one rulebook
The 2026-27 Washington pamphlet splits the Snohomish at the Highway 9 bridge, from the Burlington Northern railroad bridges at the mouth up to Highway 9, and from Highway 9 up to the confluence, but the rules on both are nearly the same. From September 26 through November 1 there is a night closure, single-point barbless hooks are required and the anti-snagging rule applies. Salmon are open for those same dates, minimum size 12 inches, 2 a day, and Chinook and chum must be released, which in practice makes it a coho fishery.
All game fish are closed from February 1 through September 25. From September 26 through January 31, Dolly Varden and bull trout may be kept at 20 inches or more as part of the trout limit, and cutthroat and wild rainbow trout have a 14-inch minimum; other game fish follow statewide rules. Sturgeon are catch-and-release only, year-round, with a night closure, and only below the Highway 9 bridge; sturgeon anglers are exempt from the small-hook part of the anti-snagging rule and may use a single-point barbless hook of any size.
After November 1
When the salmon season ends the river stays open for game fish through January 31. That is a different trip, with Dolly Varden and cutthroat as the target instead of coho. Measure any Dolly you mean to keep; under 20 inches it goes back. Because the Snohomish drains the west slope of the Cascades from Snoqualmie Pass to north of Stevens Pass, November and December rain can send it high and brown for days at a time, and the November mean at Monroe is more than five times the September mean, so plan around the gauge rather than the calendar.
Monroe gauge, closed water
USGS 12150800 sits near Monroe, right at the confluence, which this fall is inside the closed reach. It still tells you what is coming downstream to the open water. The long-term average is about 9,500 cfs, but late summer is far lower: monthly means since 2010 are about 2,320 cfs in August, 2,640 in September, 6,900 in October and 13,900 in November. No shop publishes a range for this gauge, so the 2,500 to 7,000 cfs band here is the September to October span of those means, the heart of the coho season.
On September 24, 2026 Monroe read 1,300 cfs, about half the September mean. WDFW cited low river flows as part of the reason for its September changes on the neighboring Skagit, and the Snohomish opens this year in the same dry pattern.