Colorado has 13,000 km (8,000 miles) of rivers and more than 2,000 lakes. If you are into fishing, you'll have plenty of locations to choose from and beautiful views as a bonus. Another great thing is that you can go fishing at any time of the year if you are not afraid to stay outside in the cold. For the most comfortable weather opt for the period between May and October.
In Colorado, you'll need a fishing license. They are available on April 1st each year and are good through March 31 of the following year. There are also 1-day and 5-day passes sold by Colorado Parks & Wildlife.
The Northwest region is often called Trout heaven on earth. Check out the Fryingpan River just east of Basalt below Ruedi Reservoir or Roaring Fork River and Colorado River, Pearl Lake State Park or Steamboat Lake State Park.
The Denver area also offers great fishing at Charlie Meyers State Wildlife on the South Platte River between Spinney Mountain State Park and Eleven Mile State Park. There is also Cherry Creek State Park, Chatfield State Park and Standley Lake. You can also try Clear Creek Canyon near Golden or South Boulder Creek near Boulder.
Rocky Mountain National Park also offers unbelievably good trout fishing, amazing walleye and smallmouth bass fishing at Horsetooth Reservoir, Boyd Lake State Park and Carter Lake.