Barrier Dam is the end of the line
Returning salmon and steelhead on the Cowlitz run into the Barrier Dam below Mayfield, which steers them into the Cowlitz Salmon Hatchery's ladder and sorting separator. The hatchery opened in 1968 and, by Wikipedia's figure, turns out nearly 13 million fish a year. Tacoma Power, which built Mayfield in 1963 and Mossyrock in 1968, runs the separator and trucks some of the fish on upstream: in the week before September 21, 2026 it moved coho, spring Chinook and cutthroat to Lake Scanewa, to Franklin Bridge in Packwood, to the Cispus near Yellowjacket Creek and to the Tilton at Bremer Bridge.
For anglers, that concentration is the point. The water from 400 feet below the Barrier Dam up to the salmon hatchery intake, about 1,700 feet upstream, is closed, so the fishing starts at that deadline. WDFW's Barrier Dam access site, owned by Tacoma Power, has a concrete ramp and three fishing platforms.
Blue Creek and the trout hatchery outfall
Downstream, Blue Creek comes in at the Cowlitz Trout Hatchery, where WDFW lists ADA fishing platforms beside Tacoma Power's Blue Creek launch. Blue Creek itself is open from its mouth up to a posted sign above the rearing-pond outlet, with a night closure and the anti-snagging rule. You may keep 3 hatchery steelhead, 20 inches or longer, from the Saturday before Memorial Day through April 15, and salmon from August 1 through December 31, 6 a day including 2 adults. Above the sign to Spencer Road is closed.
The 2026-27 pamphlet also reserves water for anglers with disabilities: a 100-foot radius around the trout hatchery outfall for wheelchair users holding a designated harvester companion card, and a 100-foot radius at the salmon hatchery wheelchair ramp for companion card holders.
A river counted every week
Tacoma Power's weekly Cowlitz Fish Report is the best trip planner on this river, because it shows what reached the separator. The week reported on September 21, 2026 had 653 coho adults, 136 coho jacks, 20 summer-run steelhead, 27 spring Chinook adults, 119 fall Chinook adults, 51 fall Chinook jacks and 40 cutthroat. By WDFW season dates and those counts, the year runs spring Chinook in spring and early summer, summer steelhead through summer and early fall, coho building from September, and winter steelhead in the cold months. Emerald Water Anglers calls the Cowlitz Washington's largest producer of hatchery steelhead and fishes coho from October into December on 5 to 8-weights.
The separator counts are fish that have already reached the top of the river, so a strong week there usually means more of the same run is still spread through the water downstream. Tacoma also posts weekly adult returns and collection tables by species on the same page, which let you compare this year with the last.
Olequa, Lexington, Mill Creek and the dam
WDFW's 2026-27 rules split the Cowlitz at the Lexington Bridge and at Mill Creek. From the mouth to Mill Creek you need the Columbia River Salmon and Steelhead Endorsement, two poles are allowed, and hatchery steelhead are open all year, 3 a day with a 20-inch minimum. Salmon from January 1 through July 31 are 6 a day including 2 adults, hatchery Chinook and hatchery coho only; from August 1 through December 31 it is hatchery coho only, 6 a day including 3 adults, which means this fall's Chinook go back. Trout are open from the Saturday before Memorial Day through March 31, 5 a day at 8 inches, releasing wild cutthroat and wild rainbows.
From Mill Creek to 400 feet below the Barrier Dam the same limits apply, but no fishing from any floating device, a night closure and the anti-snagging rule from April 1 through November 30, and no fishing from the south bank from May 1 through June 15. Above the hatchery intake to 400 feet below Mayfield Powerhouse the river opens again. As of September 24, 2026 WDFW listed no emergency rules for the Cowlitz beyond February's smelt dips. Downstream launches include Massey Bar, the I-5 Bridge and Olequa Crossing; Toledo is bank only and Wallace Bar is a 25-foot walk-in easement.
What Mayfield is releasing
USGS 14238000 below Mayfield Dam reads Tacoma Power's release, the same number the weekly report quotes. On Monday, September 21, 2026 that was 2,360 cfs, with eight feet of visibility and 52.2-degree water, and Tacoma adds that flows can change at any time. No shop publishes a range, so the 2,300 to 10,000 cfs on this page runs from that clear, fishable September release up to the January monthly mean since 2010, about 10,020. August and September average near 3,400 and 3,200, November about 7,380. On September 24, 2026 the gauge read 2,370.