Dillon Dam through Silverthorne
The Blue River tailwater begins at the base of Dillon Dam and runs through the town of Silverthorne, past the outlet stores and along the Blue River Parkway, with the paved river trail and town parks giving walk-in access for the whole stretch. Water comes off the bottom of Dillon Reservoir in the low 40s F, so the trout eat mysis shrimp flushed from the lake and midges most of the year, and the surface fishing is a mid-day and afternoon game. Sight fishing to visible fish with 5X and 6X and flies in the 18 to 24 range is the standard approach. The gauge on this page is the USGS station just below the dam.
North of Silverthorne to Green Mountain Reservoir
Below town Colorado 9 follows the river north toward Green Mountain Reservoir, but most of this valley is private ranch land. Public access is at the Colorado Parks and Wildlife parcels along the highway: Blue River State Wildlife Area, the Sutton Unit, Eagles Nest and the Blue River campground. Local shops say fish numbers in the public pieces are lower than in town, but big trout from the private water move through, and kokanee run up from the reservoir in fall.
Below Green Mountain Reservoir
From Green Mountain Dam the lower Blue drops through a canyon for about three public miles and continues to the Colorado River at Kremmling. This reach is a second Gold Medal section with far more insect variety than the town water, including golden stones, green drakes and PMDs. The USGS gauge below Green Mountain Reservoir (09057500) is the one to check for this reach; guides float the ranch section above 500 cfs and the canyon down to about 300 cfs.
Rainbow trout
Rainbows are the fish most anglers see in Silverthorne, and the mysis diet grows a few of them very large; the shop behind the river reports trout over 24 inches sighted regularly below the dam. Pat Dorsey, who guides the river, describes the catch as mostly browns with cutbows and some rainbows, so expect both. Winter fishing is good on midges whenever the wind allows, and the flows rarely change much from week to week.
Brown trout
Browns are present throughout and dominate the lower river and the private water north of town. They are the fall fish, feeding on baetis in September and October and on streamers through the Green Mountain canyon.
Season and regulations
The Blue is open year-round. From Dillon Dam downstream to the north city limits of Silverthorne it is artificial flies and lures only and all trout must be released immediately. From the Colorado 9 bridge at Blue River State Wildlife Area downstream to the Green Mountain Reservoir inlet the rule is flies and lures only with a 2-trout limit and a 16-inch minimum. Gold Medal designations cover Dillon Dam to Hamilton Creek Road bridge and Green Mountain Dam to the Colorado River. The seasonal September 15 to December 1 closure in the 2026 brochure applies to the Blue above Dillon Reservoir, not to the tailwater.
Denver Water sets the release from Dillon; it can sit near 50 cfs through a dry fall and jumps sharply when the reservoir fills and spills in spring. Local sources put comfortable wading in town at roughly 80 to 300 cfs, and the town water is not floatable. Check the current Colorado Parks and Wildlife brochure before you go.