Water temp of 77 - too warm for chinook?

The water temperature in the Willamette has risen to about 77 degrees.
I know there are emergency regulations now that say we can’t fish in the W from 2pm to 1 hour before sunrise, but what do you think? I’m hoping it cools a little but when is the water too warm to target chinook?

At those temperatures the chinook will not survive. Here in Alaska when our smaller streams like the Anchor River hit 70°F and above the kings are extremely stressed and even seek shady sections of the river to stay cool. Even if it means only being in 1 foot of water compared to a hole 4 feet deep in the sun.  We see perfectly healthy-looking kings laying dead on gravel bars all along the river. Heat stroke!

I monitored clarity and water temperature conditions on the Kenai River for many years and correlated them to how the early and late run Chinook fisheries were doing with respect to angler success. It helped to have an ADFG biologist assigned to the Kenai River living next door to me as we both were interested in the findings.

Our Kenai kings "preferred" 50°F to 60°F water temps that produced the best success for anglers. Fish were willing biters. From 60° to 65° there was a noticeable drop in angler hookups even when sonar counts were stable or increasing in numbers.

When the river would hit the upper 60's the fish completely turned off the bite, even the 'first light bite'. And you will see them rolling all over the surface as an indicator. When they would start rolling you might as well go home and mow the lawn.

The only potential savior for your runs will be for them to remain down in the lower reaches of tidewater where the temperatures are OK.  The Klamath River in Norcal in the fall would often heat up during the September indian summer and the kings, silvers, and steelhead would not run the river until we would get a hard rain to cool down the river.

Hopefully your fish will exhibit the same strategy for those which have not committed to the hot water yet.

Below is the sort of charts I was posting each day I took readings when I was running the website.  Also anything below 15 inches of visibility made it worthless to go fishing until the mud cleared.

The water temperature in the Willamette has risen to about 77 degrees.
I know there are emergency regulations now that say we can’t fish in the W from 2pm to 1 hour before sunrise, but what do you think? I’m hoping it cools a little but when is the water too warm to target chinook?

The fish will hold in the lower river as those are surface temperatures and there will be cooler water down deeper. The issue is when they hit the ladders at the falls they will run into that warm water and turn around. The later and later arrival of these fish is coming back to bite them in the ass. Hopefully you get some cooler days and perhaps rain (unlikely I know) to help those fish move upstream.