Eklutna Tailrace is the only tributary on the Knik River which King fishing is allowed. That would mean King fishing on Jim Creek is prohibited. I have fished the area for 20 years now and I have seen no traces of King salmon, but that does not mean they are there. I am sure a small school arrives each year, but I have not seen them even in the early season. I have heard reports of people catching small kings during the begining of silver season. I will believe it when I see it.
Not in Jim Creek, But:
In a slough just above the railroad tracks about a hundred yards, on the south bank of the Knik River, between the Parks Hwy and the Eklutna Tailrace, the kings always bunch up there. Schools of them as well as reds, silvers and dollies can be taken there without the crowds. The slough is a feeder stream from a pot hole lake, visible from the old Glenn Hwy.
I would bet most of these supposed Kings caught in Jim Creek are larger than normal silvers. I have caught some monster silvers out of the Knik and Matanuska Rivers, and I would imagine they could easily be mistaken for Kings.
Its not uncommon for silvers to trickly into Jim Creek this time of year, especially this year they were ungodly early.
I posted a message towards the end of July when the silvers first started arriving at Jim Creek. I caught a king in the hole before the trees that was 15 to 20 pounds. He was a little blushed but still silvery. Let him go of course.