For the next day or so, you'll be better off fishing still water trout and bass ponds, but I'd recommend hitting ponds anytime this spring. The trout fishing on lakes and ponds this time of year can be very good. Fish are going to be found near the surface and in shallow where the water warms more quickly. Stripping small buggers and nymphs from just under the surface to about 6' down will draw strikes. Vary your retrieve and change flies often until you dial in what the fish want. I strip three flies until I figure out what they are on. You can also use a dry dropper rig or Indicator rig with a nymph, chrominid, or worm suspending below. Scan the surface of the water for any insects, birds fly low (eating bugs) and for rises. If you see any of these signs that will be where you want to fish. Most of the bugs hatching this early will be midges of varying sizes, so a chrominid is a good choice for fly.
Once the rivers come down the fishing should begin to pick up. As always this time of year it is generally a quality over quantity game and some of the biggest fish in the rivers are caught. I know some friends have gotten into some beautiful browns and rainbows. We have 70's forecast next week so the water will begin to warm, causing insects and fish to be more active. Keep in mind that there is still an insane amount of snow in the mountains so on hot sunny days rivers may run off color in the PM from snowmelt.
Your best bet on flies will be larger attractor nymphs like stoneflies, buggers, worms, bigger pheasant tails and the like, but fish your nymphs in tandem with a small natural nymph like a green caddis larvae or hares ear. I remember fishing early season on a mid sized trib and took a 16" brown on a dead drifted white bugger and then two casts later an 18" brown on my green caddis larvae dropper. Make sure you get your flies down to the bottom by using heavy tungsten beads or adding split shot. Streamers are a good option as well this time of year. I use a 6 wt rod with Orvis Bank Shot line, which is a sink tip line to get the streamer down quickly. I'll report back as conditions improve and bugs start hatching soon.