If you want some where within 2 hours of denver hit the Cheesman Canyon stretch of the South Platte...only on a weekday though, it can get crowded on the weekends. theres lots of decent fish if you hike up into the canyon, and March usually has some good BWO hatches. ive cast over more than a few double digit fish there in the winter, and you will usually catch something if you are good at sight fishing with the small stuff....