Fishing below Ft. Peck is a seriously mixed bag if you're fishing from the shores for trout. Yeah there's trout but there's a ton of pike and walleye down there, too. They're all usually pretty good size fish, though. The guy who runs the Lakeridge tackle shop up on top of the dam is very nice but if you aren't fishing from a boat for giant trophy this and that, he doesn't have much to offer, so try to be prepared before you get there.
Anyone who tells you to fish under the bridge where the water enters those swimming hole dredges is not your friend. And that pond that's labeled "trout pond recreation area" on the Google maps down there is also full of pike.
Stop in at Dad's Bar in Wolf Point for a drink and a snack if you've got the time. Good folks in there.