Matt,
I've fished Leavenworth County Lake many times. Cats have been rather slow there this year but I haven't been in about 3 weeks. I usually fish the East end of the lake on the bank. There is a feeder on the East end that gets pretty heavy pressure but can produce.
Its worth catching sunfish if they are in the shallows around the rock outcroppings for cut bait. I've caught cats up to 10 lbs on gut pockets there.
Good luck and get there early because folks will be crawling all over that place if the weather is nice.
Jason