You're slightly right, but a bit off base carcassman. The Compact is a federal act allowing the States to enter in dual agreement given the river fisheries constitute cross state regulations. Interstate commerc actions are under federal authority via the constituttion, but Congress (back in 1918) didn't want to constantly have to pay for or have a federal agency manage the Col R, so they said "OR & WA, we'll grant you authority to do this if you can agree". Well if they can't, then the official waters of WA/OR are then managed officially by whatever regs they may set ... but it ends being a nightmare ... and yes, it may actually legally then revert to federal authority, as its a violation of the original federal act.

In regards to where the majority of fish are produced...well for spring Chinook, the VAST majority are produced in Idaho. So closing the fishery benefits them the most. Same with steelhead, most of the hatchery production is far upriver in Idaho.

Fall Chinook then yeah, its more Washington. Coho, I think its about 50/50 WA and OR, but not sure.

SO overall, your idea of simply closing the lower river DOES NOT benefit WA fishermen...it benefits ID the most.