Re: Colorado in March?
I am surprised that no one mentioned the S. Platte. In fact, I think the Platte runs through Denver - not to say that you should fish in downtown, if it exists.
There are two tailwater fisheries on the S. Platte that are Gold Medal Waters; Cheesman Canyon and Spinney Mtn. section. Cheesman requires a hike in but the trout are legendary, Spinney is easier to get to and has superb meanders to fish. But, remember it is March and you can get snow at any time. Of the two, Spinney is nice and a favorite of mine. My avatar has a 24 inch bow from that section. Because they are tailwaters, the water will be flowing and you can get into some hatches. Again, it has to do with access because of the snow.
Angler's Covey in Co. Springs can give the up to date scoup on the fishing on the S. Platte.
Living large in the Southwest.