Green Mountain Reservoir, CO

About Green Mountain Reservoir

Green Mountain Reservoir is a deep, high-country impoundment on the Blue River in Summit County, Colorado, sitting at roughly 8,000 feet of elevation in the shadow of the Gore Range. Built behind Green Mountain Dam as part of the Colorado-Big Thompson water project, it stretches several miles north of Silverthorne and offers a big, open expanse of cold, clear water surrounded by sagebrush hills and pine-covered ridges. Among Front Range and mountain anglers, it is best known as one of Colorado's most reliable kokanee salmon fisheries.

What sets Green Mountain apart is the mix of a healthy landlocked kokanee population layered over a coldwater trout and lake trout (mackinaw) fishery, all in a scenic reservoir that draws both serious trollers and casual shoreline anglers. Water levels swing widely through the season as the reservoir is drawn down for irrigation and downstream demand, so the lake fishes differently from a full, high-water spring to a low, exposed-shoreline fall. That fluctuation, combined with depth and cold temperatures, is the backdrop for nearly every pattern that works here.

Fish Species

Green Mountain Reservoir holds a coldwater mix typical of high Colorado impoundments, with a few clear standouts:

• Kokanee salmon — the signature fish. These landlocked sockeye run in schools, feed on zooplankton, and turn brilliant red as they stage for their fall spawning run up the Blue River. They are the reason many anglers make the trip.
• Lake trout (mackinaw) — present in the deeper basins and capable of reaching solid sizes. They are the apex predator here and are targeted by anglers jigging and trolling deep.
• Rainbow trout — common and stocked, providing steady action for trollers and bait anglers from shore.
• Brown trout — present in the reservoir and the connected Blue River, offering a chance at a larger, wild-feeling fish.

You may also encounter other trout and the occasional incidental species, but kokanee and lake trout are what give Green Mountain its reputation, with rainbows and browns rounding out the fishery.

Best Seasons & Times

Spring (ice-off through June): As the ice releases, fish that wintered deep move shallower and feed actively in the warming surface and mid-depth water. Early-season trolling for rainbows and cruising trout near the upper end and inflows can be excellent, and kokanee begin to school up. Mornings are prime before boat traffic and wind build.

Summer (July–August): As surface water warms, kokanee and lake trout slide deeper to find the cold, oxygenated layer. This is downrigger and lead-core season — locate the thermocline and the schools with electronics. Early morning and the last hour of light are the most productive windows, and calm mornings beat the afternoon mountain wind.

Fall (September–October): The headline season for kokanee. Maturing fish color up bright red and stage near the upper reservoir and the Blue River inlet ahead of their spawning run. They grow aggressive and territorial, making them more willing to strike. Reservoir drawdown concentrates fish, and cooler water spreads trout through more of the water column.

Winter: When safe ice forms, Green Mountain can offer hard-water fishing, but high-elevation conditions and fluctuating water levels make ice quality variable and sometimes unsafe. Always verify current ice conditions locally before venturing out, and treat early and late ice with extra caution.

Techniques & Baits

For kokanee: Trolling is king. Run small, flashy lures — pink, orange, or chartreuse hoochies, squid skirts, and tiny spoons — behind a dodger or flasher to imitate the flash of a feeding school. Tip hooks with white shoepeg corn (often scented) for a proven kokanee trigger. Use a downrigger or lead-core line to reach their depth, run slow (roughly 1 to 1.5 mph), and work the depth where your electronics mark schools. In fall, brightly colored gear near staging areas takes aggressive, spawning-stage fish.

For lake trout: Go deep. Vertical jigging with tube jigs, white or chartreuse soft plastics, and heavy spoons over the deeper basins is effective, as is trolling large minnow-imitating plugs and spoons near the bottom with a downrigger. A quality sonar to find structure and suspended fish makes a big difference.

For rainbows and browns: From shore, fish PowerBait, nightcrawlers, or salmon eggs on a slip-sinker rig, or cast spinners and spoons. Trollers do well with cowbells/flasher rigs trailing a worm, small spoons, and crankbaits in the upper water column in spring and fall. Fly anglers can find action near inlets and along drop-offs with streamers and attractor patterns.

• Mind the changing water level — productive shoreline spots shift as the reservoir is drawn down.
• Match your presentation depth to the thermocline in summer; fish the top in spring and fall.

Access & Launches

Green Mountain Reservoir lies within the White River National Forest north of Silverthorne, just off Colorado Highway 9, which makes it relatively easy to reach from the I-70 corridor. The reservoir offers public access for both boaters and shore anglers, with developed boat-launch facilities and several Forest Service campgrounds and day-use areas spread along the shoreline. Both the eastern and western sides see angler use, and the upper (north) end near the Blue River inflow is a popular area, especially during the fall kokanee run.

Because this is a National Forest reservoir, expect public ramps, primitive and developed camping, and open shoreline rather than a single managed marina complex. Water levels fluctuate substantially, so ramp usability and shoreline footing change through the season — it is wise to confirm current launch conditions before hauling a boat. Plan for high-elevation weather, afternoon wind, and limited services on site.

Regulations & Licenses

A valid Colorado fishing license is required for all anglers of licensing age, and you should carry it whenever you fish here. Colorado Parks and Wildlife sets the rules that govern Green Mountain Reservoir, and they can include species-specific bag and possession limits, gear restrictions, and special provisions — kokanee salmon in particular are often subject to their own limits and may have snagging seasons or gear rules tied to the spawning run in some Colorado waters.

Limits and regulations change from year to year and can differ between the reservoir and the connected Blue River, so always check the current Colorado Parks and Wildlife fishing regulations brochure (and any site-specific or seasonal notices) before your trip. Practice careful catch-and-release where appropriate, respect any closures protecting spawning fish, and follow all boating and aquatic-nuisance-species (mussel inspection) requirements that may apply.

Frequently Asked Questions

What is Green Mountain Reservoir known for catching?
It is best known for kokanee salmon, with a strong lake trout (mackinaw) fishery and good numbers of rainbow and brown trout. Kokanee are the main draw, especially during the fall when they color up red ahead of their spawning run.

When is the best time to fish for kokanee at Green Mountain Reservoir?
Kokanee fish well from late spring through fall. Summer means trolling deep near the thermocline with downriggers or lead-core line, while fall (September–October) is the marquee season as mature, bright-red fish stage near the upper reservoir and the Blue River inlet. Early morning is consistently the most productive window.

What lures and baits work best here?
For kokanee, troll small dodger/flasher rigs with pink, orange, or chartreuse hoochies and tiny spoons tipped with scented white corn. For lake trout, jig tubes and heavy spoons deep or troll big plugs near bottom. Shore anglers do well on PowerBait, nightcrawlers, and salmon eggs for rainbows, plus spinners and spoons.

Do I need a license, and are there special regulations?
Yes — a valid Colorado fishing license is required. Green Mountain Reservoir is managed by Colorado Parks and Wildlife, and bag/size limits and gear rules apply and vary by species, with kokanee often having their own limits and seasonal provisions. Always check the current CPW regulations before fishing.