Lake Dillon was formed when the Dillon Reservoir Dam was built in 1963 to provide storage for Denver’s water supply. The old town of Dillon would be flooded and many of the buildings were moved to the current towns of Dillon and Silverthorne. It took a few years for the reservoir to fill up and by the mid seventies Lake Dillon became one of Colorado’s premier Brown trout fisheries.
For many years Lake Dillon was the place to be if you wanted to catch a trophy Brown trout. Then in the early eighties Mysida shrimp, a very small fresh water shrimp were artificially introduced. It was thought that the Mysida shrimp would enhance the fishing in the reservoir due to providing forage for the brown and rainbow trout. Unfortunately, an opposite effect occurred and the Mysida shrimp population exploded out of control. The Mysida eliminated the Daphnia Zoo plankton and that sort of “whipped the rug” out from under the food chain, and the reservoir crashed and the fishing became nothing like what it used to be.
Over the years, wildlife managers have worked to bring back the fishery by stocking hundreds of thousands of fingerling Rainbow trout to fill in the gap in the food chain, providing more forage for the more mature fish in the reservoir. In the late nineties Arctic Char, a deep water dwelling species that feeds prolifically on the Mysida shrimp were introduced. Lake Dillon and one other lake in Maine are the only waters Arctic Char can be found in the lower 48.
Research by the Colorado State University as well as our catch logs and experiences fishing show that the Arctic Char are reproducing naturally and each year the fishing for them and the size of them keeps getting better.
The efforts by parks and wildlife have shown to be productive as we are experiencing the best fishing for Rainbow trout, Brown trout, Arctic Char, and Kokanee salmon that Dillion Lake has offered in many years. In addition to being only one of two reservoirs in the lower 48 that has Arctic Char, Lake Dillon has the only known naturally occurring Kokanee Salmon run. The reservoir has not been stocked with Kokanee Salmon for over 10 years, yet we see some very prolific Kokanee Salmon runs at the reservoir.