For Chatfield reservoir and surrounding area, you have a variety of options. It sounds like you like to fish for bass, so I'll start there.
For Smallmouth bass to 15 inches, try on the dam of the main lake with tubes and other crawfish imitations. There are two main rip-rap areas that you want to focus on, and that is the Massey Draw Area (northwest side of the lake) and around the Dam and tower. It is very snaggy in these areas, so lots of jigs are recommended. You can also try X-raps as well. If you go in the evenings, you have a good shot at a walleye still, and the bass seem to be more active at this time. The little cove where the boats launch near the dam is the deepest area along the dam, and I would start there.
For Largemouth Bass, forget the res. Go for the ponds on the southern end (five of them, but really only two are easily accessible, aka the gravel ponds) or the ponds north of the Dam (aka the Dog Ponds). Both are limited in cover and structure, and minnows/leeches/worms are best. You will get pestered by lots of panfish, though, so bring enough bait. If you want to get into some real bass action, go to the areas of the ponds that look less trodden upon. That means hoofing it to the opposite side of any of the ponds. Look for fallen trees/rip-rap. Weedless plastics are effective for fishing cover.
For Trout, you could try the inlet area of the res, or the spillway. I've never had much luck in the spillway, but it is worth a shot if nothing else is producing. Climb up on the catwalks and fish right where the water comes in. Worry about how to land a fish when you catch one.
Catfish aren't really active yet, but the panfish should be biting if you want a fish fry. Perch, Bluegills, and crappie are available in any of the ponds.
Good luck and let us know how you do!