Across Paxson Lake to the first riffle
The float starts at the BLM Paxson Lake Campground, Mile 175 on the Richardson Highway, where there is a paved ramp and a registration stand for boaters. You then row or paddle three miles across the lake to its outlet before there is any current. BLM charges no fee for river use. The river above Sourdough is part of the 181 miles of the Gulkana designated wild in December 1980, and the land along it is mostly federal and state.
ADF&G's float log gives the distances: 3 miles from the lake outlet to the Middle Fork, 20 more to Canyon Rapids, 19 from the rapids to the West Fork, and 8 from the West Fork to Sourdough Creek Campground, about 50 river miles in all. Its brochure calls that first 3 miles below the lake swift, boulder-strewn water with excellent grayling fishing, says lake trout and whitefish can be caught at the outlet itself, and rates early summer best for lake trout in Paxson, and ADF&G's current fishery page tells floaters to allow three to four days.
Canyon Rapids and the trout below it
Canyon Rapids is Class III to IV, and the signed portage trail on river left is used by all but the most experienced boaters. ADF&G notes good rainbow fishing below the rapids and then eight miles of small boulder rapids that hold grayling. These rainbows are the most northerly native population in North America, according to ADF&G, and they are slow-growing and few; every rainbow or steelhead in the Gulkana drainage must be released. The brochure suggests dry flies in sizes 14 to 16 for the slow water and wet flies in 10 to 12 for fast water, naming mosquito patterns, the Adams, elk-hair caddis and hare's ear nymphs. For grayling it describes skittering a fly across the surface.
Salmon rules change as you go downstream. All flowing water from 100 yards above the Paxson Lake narrows down to the Middle Fork is closed to salmon fishing, and the Middle Fork itself is closed to kings. Across the drainage, flowing water is limited to unbaited, single-hook lures or flies year-round unless a section rule says otherwise.
Sourdough, the jet boats and the bridge
Sourdough Creek Campground at Mile 147.5 is the take-out for floaters and the launch for power boats that run up toward the West Fork. BLM says it has 42 sites and accessible fishing ramps and stays busy from about Memorial Day through mid July. Below Sourdough the land is mostly private and Ahtna, Inc. property, so stay below ordinary high water or get a permit. ADF&G lists walk-in trails at Poplar Grove (Mile 136.4), Sailor's Pit (Mile 129.3) and the Richardson Highway bridge at Mile 126.9, and it is about 33 river miles from Sourdough down to that bridge.
ADF&G's fishery page puts kings in the river in June and July and sockeye from June into August, and says coho and Dolly Varden are generally absent. Grayling move into the lower creeks off the highway, such as Sourdough and Poplar Grove creeks, in early to mid May on their spawning run.
How the 2026 king season closed
The Upper Copper booklet opens king fishing January 1 to July 19 with one king 20 inches or longer a day and an annual limit of four, and in 2026 a free Upper Copper River King Salmon Sport Fishery Permit was required on top of the king stamp, reported online by August 31 even if you caught nothing. Then the Copper River run came in weak. On June 25 ADF&G cut the annual limit to one. From July 6 everything above Haley Creek, the Gulkana included, went to catch-and-release with no bait or multiple hooks. On July 10 all Upper Copper king fishing closed, including catch-and-release, with only unbaited single-hook lures allowed in flowing water through August 10. The Gulkana counting tower finished on August 12 with 3,942 kings and 16,350 sockeye.
Standing section rules on the main stem: from the Richardson Highway bridge upstream to a marker 7.5 miles above the West Fork, bait and treble hooks are normally allowed June 1 to July 19 and single-hook artificials after that. From the bridge down to about 500 yards below the Copper River, only unbaited single-hook flies are allowed June 1 to July 31, and a bead above a bare hook does not count as a fly. Grayling are 5 a day under Upper Copper general rules, but only 2 a day in waters above Paxson Lake.
What the Sourdough gauge tells a floater
USGS 15200280 is at Sourdough, the take-out, so it reads the whole float's water. The river peaks at breakup, with a long-term May mean near 3,350 cfs, then eases to about 2,750 in June and 1,400 to 1,550 from July through September. No outfitter publishes a floating range for this gauge, so the 1,400 to 2,800 cfs band here is the June through September span of those means. High June water makes Canyon Rapids pushier and the grayling harder to find in the main current; late-summer readings near the bottom of the band are the easy floating and the best dry-fly water.