When is lake trout (mackinaw) season in Colorado?

Colorado keeps lake trout (mackinaw) open to fishing year-round for the 2026 regulation year — there is no closed season, though the daily bag and size limits below still apply every day.

What is the Colorado bag limit for lake trout (mackinaw)?

The Colorado daily bag limit for lake trout (mackinaw) is 8 / day no minimum on most Mysis-driven lake-trout reservoirs (Granby + Dillon + Twin Lakes); 4 / day with only 1 fish over 28 in / day on Blue Mesa (TROPHY MANAGEMENT slot). The possession limit is 16 in possession on Mysis-driven reservoirs; 8 in possession on Blue Mesa. Some named waters set a different limit — check the water-body overrides above.

Do you need a license to fish for lake trout (mackinaw) in Colorado?

Yes. Colorado requires a valid fishing license to fish for lake trout (mackinaw), with the usual exemptions for young children, state free-fishing days, and some senior or disabled-veteran categories. A license is valid only in the state that issued it, so non-residents need a Colorado license — compare resident and non-resident Colorado fees on the state regulations page below.

Are there gear restrictions for lake trout (mackinaw) in Colorado?

Yes. In Colorado, lake trout (mackinaw) fishing carries these gear rules: Hook-and-line; trolling permitted; deep-water jigging permitted; Spearfishing permitted on listed waters during ice-fishing season; Federal NPS regulations apply within Curecanti NRA + Rocky Mountain NP (CPW Fishing License valid — NPS does NOT supersede CPW); CPW Habitat Stamp + Fishing License required ages 18+ ($11.97 res / NR Habitat Stamp + $36.08 res annual / $97.97 NR annual); CPW Second-Rod Stamp $5.31 required to fish with 2 rods simultaneously on most waters; Confirm current-year CPW Fishing Regulations for District-by-District reservoir-specific rules.

Do specific Colorado waters have different lake trout (mackinaw) rules?

Yes. 5 named Colorado waters carry rules that override the statewide lake trout (mackinaw) regulation, including Blue Mesa Reservoir, Lake Granby, Dillon Reservoir, and 2 more. See the named water-body overrides above for the exact rule on each.

2026 regulation year

Colorado Lake trout (Mackinaw) 2026 — Season, Bag Limit, Size Rules

Salvelinus namaycush

Last updated May 27, 2026

Colorado lake trout (Mackinaw) fishery is anchored by Blue Mesa Reservoir (9,180-acre Curecanti National Recreation Area NPS overlay reservoir on the Gunnison River — USBR Blue Mesa Dam built 1965 — Gunnison County — Colorado's largest body of water + country's premier inland trophy lake trout fishery) — CO state-record lake trout 50 lb 8 oz Blue Mesa 2007 (one of largest inland US lake trout records alongside WY Flaming Gorge 50 lb 0 oz 1995 + Lake Superior + Lake Michigan + Lake Huron Great Lakes lake trout fishery). Blue Mesa carries CPW slot-limit-based TROPHY MANAGEMENT — 4 / day with only 1 fish over 28 in / day — explicitly designed to protect the trophy lake trout fishery and produce 30+ lb fish consistently. Lake Granby (7,256-acre Colorado-Big Thompson Project reservoir on the Colorado River — USBR Granby Dam built 1949 — Grand County) is Colorado's premier kokanee salmon + Mysis-shrimp-driven trophy lake trout fishery — Mysis shrimp (Mysis diluviana) was introduced into Granby + Dillon + Twin Lakes deep-water cold lakes in the 1970s + has shifted the entire forage base into trophy lake trout production (20-30+ lb fish routinely). Dillon Reservoir (3,233-acre Denver Water reservoir on the Blue River at 9,017 ft elevation — Summit County — Colorado's highest-elevation major reservoir) carries Mysis-driven trophy lake trout fishery alongside Granby. Twin Lakes (Lake County — 2,700-acre USBR Twin Lakes Dam 1980 reservoir on Lake Creek tributary of the Arkansas River — high-altitude 9,200 ft elevation) carries the third major Mysis-driven trophy lake trout reservoir. Williams Fork Reservoir (Grand County) + Wolford Mountain Reservoir (Grand County) + Vallecito Reservoir (La Plata County) + Lemon Reservoir (La Plata County) carry secondary trophy lake trout reservoirs. Colorado lake trout management framework is one of the most aggressive in the country: Mysis-driven reservoirs (Granby + Dillon + Twin Lakes) carry 8 / day no minimum encouraged-harvest rule (aggressive harvest to maintain the trophy size class — younger fish are abundant + slow-growing without harvest pressure); Blue Mesa carries the 4 / day with 28 in / day slot rule (explicit slot-based TROPHY MANAGEMENT on the country's premier inland trophy lake trout fishery — CPW-distinctive slot-based rather than size-min-based protection). CPW + USFWS Leadville NFH stocks lake trout on listed reservoirs alongside the Mysis-shrimp introduction program. Open year-round on most waters.

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Season

Open year-round Open year-round on most waters; Blue Mesa slot regulation (1 fish over 28 in / day) under CPW TROPHY MANAGEMENT; Mysis-driven Granby + Dillon + Twin Lakes carry 8 / day no minimum aggressive harvest.

Bag & possession

Daily bag: 8 / day no minimum on most Mysis-driven lake-trout reservoirs (Granby + Dillon + Twin Lakes); 4 / day with only 1 fish over 28 in / day on Blue Mesa (TROPHY MANAGEMENT slot)
Possession: 16 in possession on Mysis-driven reservoirs; 8 in possession on Blue Mesa

Size, slot, trophy rules

Size: No statewide minimum; Blue Mesa slot: only 1 fish over 28 in / day TROPHY MANAGEMENT
Slot: Blue Mesa Reservoir 4 / day with only 1 fish over 28 in / day — release all fish over 28 in except the 1 trophy-allotment; CPW-distinctive slot-based protection on country's premier inland trophy lake trout fishery
Trophy rule: Blue Mesa Reservoir country's premier inland trophy lake trout fishery — CO state-record lake trout 50 lb 8 oz Blue Mesa 2007 (one of largest inland US lake trout records alongside WY Flaming Gorge 50 lb 0 oz 1995 + Lake Superior + Lake Michigan + Lake Huron Great Lakes lake trout fishery); CPW slot-limit-based TROPHY MANAGEMENT — 4 / day with only 1 fish over 28 in / day; Granby + Dillon + Twin Lakes Mysis-shrimp-driven trophy lake trout fishery (Mysis introduction 1970s shifted forage base into 20-30+ lb fish routinely); CPW-distinctive aggressive 8 / day no min on Mysis-driven reservoirs to maintain trophy size class through harvest pressure

Gear restrictions

Hook-and-line; trolling permitted; deep-water jigging permitted
Spearfishing permitted on listed waters during ice-fishing season
Federal NPS regulations apply within Curecanti NRA + Rocky Mountain NP (CPW Fishing License valid — NPS does NOT supersede CPW)
CPW Habitat Stamp + Fishing License required ages 18+ ($11.97 res / NR Habitat Stamp + $36.08 res annual / $97.97 NR annual)
CPW Second-Rod Stamp $5.31 required to fish with 2 rods simultaneously on most waters
Confirm current-year CPW Fishing Regulations for District-by-District reservoir-specific rules

Named water-body overrides

Where statewide rules differ on specific Colorado waters:

Blue Mesa Reservoir
4 / day with only 1 fish over 28 in / day TROPHY MANAGEMENT slot; CO state-record lake trout 50 lb 8 oz Blue Mesa 2007; Curecanti NRA NPS overlay
Lake Granby
8 / day no minimum (CPW aggressive harvest on Mysis-driven fishery); 20-30+ lb fish routinely on spring + fall jigging + trolling
Dillon Reservoir
8 / day no min (Mysis-driven fishery); kokanee salmon 10 / day no min
Twin Lakes
8 / day no min (Mysis-driven fishery); high-altitude trophy lake trout alongside CO state-record cutthroat 16 lb 0 oz Twin Lakes 1964
Williams Fork Reservoir + Wolford Mountain Reservoir + Vallecito Reservoir + Lemon Reservoir
8 / day no min combined trout; trophy lake trout alongside kokanee + brown trout fishery

Official source

Colorado Parks and Wildlife (CPW) publishes the authoritative 2026 Coloradofishing regulations. Always verify the current rule before fishing — emergency closures and in-season changes can override what's published here.

Visit official Colorado fishing regulations →

Emergency-order channel

Lake trout (Mackinaw) closures, slot-limit changes, and harvest pauses are posted to Colorado Parks and Wildlife's emergency-order feed — check it before any Colorado trip during the active season.

Frequently asked questions

When is lake trout (mackinaw) season in Colorado?: Colorado keeps lake trout (mackinaw) open to fishing year-round for the 2026 regulation year — there is no closed season, though the daily bag and size limits below still apply every day.
What is the Colorado bag limit for lake trout (mackinaw)?: The Colorado daily bag limit for lake trout (mackinaw) is 8 / day no minimum on most Mysis-driven lake-trout reservoirs (Granby + Dillon + Twin Lakes); 4 / day with only 1 fish over 28 in / day on Blue Mesa (TROPHY MANAGEMENT slot). The possession limit is 16 in possession on Mysis-driven reservoirs; 8 in possession on Blue Mesa. Some named waters set a different limit — check the water-body overrides above.
What size lake trout (mackinaw) can you keep in Colorado?: The Colorado size rule for lake trout (mackinaw) is No statewide minimum; Blue Mesa slot: only 1 fish over 28 in / day TROPHY MANAGEMENT. Slot limit: Blue Mesa Reservoir 4 / day with only 1 fish over 28 in / day — release all fish over 28 in except the 1 trophy-allotment; CPW-distinctive slot-based protection on country's premier inland trophy lake trout fishery. Trophy rule: Blue Mesa Reservoir country's premier inland trophy lake trout fishery — CO state-record lake trout 50 lb 8 oz Blue Mesa 2007 (one of largest inland US lake trout records alongside WY Flaming Gorge 50 lb 0 oz 1995 + Lake Superior + Lake Michigan + Lake Huron Great Lakes lake trout fishery); CPW slot-limit-based TROPHY MANAGEMENT — 4 / day with only 1 fish over 28 in / day; Granby + Dillon + Twin Lakes Mysis-shrimp-driven trophy lake trout fishery (Mysis introduction 1970s shifted forage base into 20-30+ lb fish routinely); CPW-distinctive aggressive 8 / day no min on Mysis-driven reservoirs to maintain trophy size class through harvest pressure.
Do you need a license to fish for lake trout (mackinaw) in Colorado?: Yes. Colorado requires a valid fishing license to fish for lake trout (mackinaw), with the usual exemptions for young children, state free-fishing days, and some senior or disabled-veteran categories. A license is valid only in the state that issued it, so non-residents need a Colorado license — compare resident and non-resident Colorado fees on the state regulations page below.
Are there gear restrictions for lake trout (mackinaw) in Colorado?: Yes. In Colorado, lake trout (mackinaw) fishing carries these gear rules: Hook-and-line; trolling permitted; deep-water jigging permitted; Spearfishing permitted on listed waters during ice-fishing season; Federal NPS regulations apply within Curecanti NRA + Rocky Mountain NP (CPW Fishing License valid — NPS does NOT supersede CPW); CPW Habitat Stamp + Fishing License required ages 18+ ($11.97 res / NR Habitat Stamp + $36.08 res annual / $97.97 NR annual); CPW Second-Rod Stamp $5.31 required to fish with 2 rods simultaneously on most waters; Confirm current-year CPW Fishing Regulations for District-by-District reservoir-specific rules.
Do specific Colorado waters have different lake trout (mackinaw) rules?: Yes. 5 named Colorado waters carry rules that override the statewide lake trout (mackinaw) regulation, including Blue Mesa Reservoir, Lake Granby, Dillon Reservoir, and 2 more. See the named water-body overrides above for the exact rule on each.

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