To show the salmon-centric view of WDFW on the Cowlitz, when the agreement with FERC and Tacoma was reached one clause had it that up and downstream passage needed to installed above the Cowlitz Falls dam IF Either spring chinook OR winter steelhead showed a sustainable run. The initial fish collection structure worked well for steelhead; they were close to being sustainable back then. But it didn't catch diddle-e-squat chinook. So the abandoned the successful trap (steelhead), went for salmon, and succeeded with neither.