About 3 years ago, the cat fishing and wiper fishing was excellent. Then it went to dead pool. They rescued a bunch of fish at the outlet and put them back in the lake. Last year wasn't as bad and this year, it is at full pool (at least before the irrigation starts). As mentioned, they've stocked it again.
Prewitt is between Brush and Sterling - you can see it from I-76. If you're going from Denver, get off at the Moreno exit and go west, then head north. The entrance will be on the right hand side.
I've seen wall to wall wiper fisherman at the inlet in the past. I've fished for catfish along the road in the coves right in amongst the brush. Per the DOW report, the boat ramp is scheduled to go in today (weather permitting). You can also fish right from the dam.
Just make sure you're 100% legal. The DOW usually patrols it once in the evening and the local sherriff patrols about every hour (meth labs are a problem in Eastern Colorado-one was busted at the North Sterling campground last fall).