It’s no secret the best places to catch lower Columbia River summer steelhead in August are just downstream of Bonneville Dam, at the mouth of the Cowlitz River or off the beaches near Cathlamet.
Come September, there’s a reason why 250 boats are anchored in waves of hoglines between the Cowlitz mouth and the Longview Bridge.
Not all stretches of the Columbia River produce salmon and steelhead for anglers equally.
There are portions — like the Camas-Troutdale area — that produce chinook and steelhead at much slower rates than most other parts of the lower river.
For example, in September 2009, 13 salmon or steelhead were caught per 100 trips in the Camas-Government Island stretch of the Columbia. At the Cowlitz River mouth, the average was 44 salmon-steelhead per 100 trips in the same month.
And how to we know that?
Because Washington and Oregon combined spend about $1 million each year between February and October sampling sport fishermen.
Joe Hymer of the Washington Department of Fish and Wildlife said there are six full-time samplers and nine temporaries working this summer and fall just on the north side of the lower Columbia.
The river between Bonneville Dam and Tongue Point is divided into 10 sections for sampling purposes.
“We can sample all 10 sections in a day when we’re at maximum if there are no commercial seasons,’’ Hymer said.
Oregon has 11 samplers for its side, said Jimmy Watts of the Oregon Department of Fish and Wildlife.
The Columbian has examined the sport catch data compiled by the two states trying to determine — statistically, not just back of the boat talk — which areas of the river fish best in August and September.
For purposes of this story, any chinook, steelhead or coho counted as a catch. it did not matter if the salmon was a jack or if the fish were released.
The numbers on the accompanying chart are “catch-per-unit-effort,’’ a commonly used measure of angling success. If two anglers go fishing, and they get one fish, the CPUE is .5. If eight go fishing, and they catch one, the CPUE is .125.
What does the data show?
August is a steelhead month. Steelhead stacked up just downstream of Bonneville Dam provide the best fishing. The plume of cool water at the mouth of the Cowlitz River is good, as are the beaches on the Washington side.
“The bank anglers in Washington do well in August for steelhead, but the only hotspot in Oregon is in the (Columbia) Gorge,’’ Watts said. “That’s partially because the Willamette flows down our side and it can be 75-plus degrees.’’
Watts isn’t kidding about the Oregon side at Bonneville Dam being a steelhead hotspot.
In 2009, Oregon bank anglers at Bonneville caught 56 fish (88 percent steelhead) per 100 trips. They did even better in 2010, at 65 fish (94 percent steelhead) per 100 trips.
The Washington side is just as good, with 70 fish (98 percent steelhead) per 100 trips in August 2009 and 63 (96 percent steelhead) per 100 trips in August 2010.
Boaters do well near Bonneville in August, too. In 2009, boaters in the Gorge caught 31 fish per 100 trips. It was better for them in August 2010, at 45 fish per 100 trips.
“It’s mostly from Beacon Rock upstream,’’ Hymer said about August steelhead catches in the Gorge. “Steelhead like little points and dropoffs and near tributary creeks.’’
Fishing from a boat at the mouth of the Cowlitz is hugely popular in both August and September — for good reason.
The CPUE in August was .45 and .31 in 2009 and 2010, respectively. Those are good CPUEs, plus the catch was 55 percent chinook in 2009 and 34 percent chinook in 2010.
September is a chinook month. Steelhead catches plummet.
Everyone knows the mouth of the Cowlitz is the place to be during September, and it seems everybody is there most days.
CPUEs were .44 in September 2009 and .34 in September 2010.
Crowding can be intense. Some boaters anchor downstream, closer to the Longview Bridge or upstream in Carrolls Slough. The slough is the back channel between Cottonwood Island and the Washington shore.
The bi-state data also shows fall chinook fishing is good in the Cathlamet area (west tip of Wallace Island to west tip of Puget Island) in September.
A sleeper spot in September some years is just upstream of the Tongue Point, Ore.-Rocky Point, Wash. line. The line is the upstream boundary of the Buoy 10 fishing area.
“We don’t see much effort above the Tongue Point-Rocky Point line until Buoy 10 closes to chinook retention,’’ Watts said.
“The area just above the line can get pretty good at times, but it usually doesn’t last long.’’