I too grew up fishing the Cedar for Steelhead. It was amazing that an urban run of fish could withstand the pressures placed upon it. The Cedar watershed is the primary source of water for the city of Seattle. The upper river has been closed to fishing for a lot of years to protect the water quality. Below the dams is where the troubles began. The city would shut off the water from the resorvoir to lower the water level in Lake Washington so that people could repair their boat docks. This would drain the river to a trickle. Of course if there were heavy rainfalls in the watershed they would then have to open the floodgates and the river would become a raging torrent. The fish remarkably survived that abuse. The fish also survived the "trout" fishery that occured. In reality most of these were steelhead smolts.
I remember "Hershal" and his gang below the locks that decimated several consecutive returning age groups of adult fish. I remember how people came from far and wide to watch these useless marine mammels catch steelhead and tear their bellies out, one after another after another. Top this with tribal netting and it was easy to see why the run collapsed.