Two canoes crossing open water between forested points in the Boundary Waters

Updated August 2026

Biggest Lake in Colorado: Blue Mesa Reservoir (9,180 acres)

Blue Mesa Reservoir is Colorado's largest inland lake per the Bureau of Reclamation (Aspinall Unit) / NPS Curecanti NRA / USACE National Inventory of Dams. Below: 50 Colorado lakes ranked by surface area.

The largest lake in Colorado is Blue Mesa Reservoir at 9,180 acres , in Gunnison County, according to the Bureau of Reclamation (Aspinall Unit) / NPS Curecanti NRA / USACE National Inventory of Dams. Navajo Reservoir is larger at 19,000 acres. Straddles the Colorado-New Mexico line. Navajo Dam and the bulk of the pool are in New Mexico, so it is not a Colorado lake even though the upper end reaches Archuleta County (USACE NID NM00120: 19,000 acres).

See our Blue Mesa Reservoir water-quality report card D

Source: Bureau of Reclamation (Aspinall Unit) / NPS Curecanti NRA / USACE National Inventory of Dams (2026-07-30). The table below ranks the Colorado lakes in our own index by surface area.

Lakes with area data

11,590

Largest (acres)

1,788

Median of top 50

31/50

Reservoirs (vs natural)

Reading Colorado's size profile

Colorado's largest lake by surface area is John Martin Reservoir in Bent County, spanning 11,590 acres. Most of Colorado's biggest waters are reservoirs — dammed river valleys built for water supply, flood control, and recreation, so their footprints shift with pool level.

Surface area is a poor proxy for water quality on its own — a large lake can hold a clean, deep core and a nutrient-loaded bay at the same time. Each lake below links to its full report card with grade, clarity, depth, and EPA impairment status. Area figures come from state DNR surveys and the USACE National Inventory of Dams; grades come from EPA and state monitoring data.

The 50 biggest lakes in Colorado by surface area

#	Lake	County	Surface area	Max depth	Grade
1	John Martin Reservoir	Bent	11,590 acres	-	NR
2	Lake Granby Dam Bottom	Grand	7,260 acres	-	B
3	Lake Meredith	Crowley	6,223 acres	-	NR
4	Pueblo Reservoir	Pueblo	5,671 acres	-	A
5	Adobe Creek Reservoir	Bent	5,094 acres	-	NR
6	Mcphee Reservoir	Montezuma	4,918 acres	-	NR
7	Nee Noshe Reservoir	Kiowa	3,696 acres	-	NR
8	Riverside Reservoir	Weld	3,633 acres	-	NR
9	Carter Reservoir	Larimer	3,551 acres	-	NR
10	Antero Reservoir	Park	3,446 acres	-	C
11	Dillon Reservoir	Summit	3,300 acres	-	D
12	North Sterling Reservoir	Logan	2,880 acres	-	F
13	Milton Reservoir	Weld	2,660 acres	-	NR
14	Vallecito Reservoir	La Plata	2,603 acres	-	NR
15	Empire Reservoir	Weld	2,486 acres	-	NR
16	Jackson Reservoir	Morgan	2,427 acres	-	D
17	Spinney Mountain Reservoir	Park	2,403 acres	-	NR
18	Prewitt Reservoir	Washington	2,329 acres	-	NR
19	Horse Creek Reservoir	Otero	2,181 acres	-	NR
20	Green Mountain Reservoir	Summit	2,125 acres	-	A
21	Taylor Park Reservoir	Gunnison	2,038 acres	-	NR
22	Shadow Mountain Lake	Grand	1,852 acres	-	D
23	Bonny Reservoir	Yuma	1,846 acres	-	NR
24	Barr Lake	Adams	1,830 acres	-	NR
25	Horsetooth Reservoir	Larimer	1,817 acres	-	NR
26	Turquoise Reservoir	Lake	1,788 acres	-	D
27	Boyd Lake	Larimer	1,747 acres	-	A
28	Wolford Mountain Reservoir	Grand	1,550 acres	-	C
29	Williams Fork Reservoir	Grand	1,549 acres	-	NR
30	Lake Nighthorse	La Plata	1,548 acres	-	C
31	Trinidad Reservoir	Las Animas	1,442 acres	-	C
32	Julesburg Reservoir	Sedgwick	1,418 acres	-	NR
33	Standley Lake	Jefferson	1,222 acres	-	NR
34	Neesopah Reservoir	Kiowa	1,216 acres	-	NR
35	Lake Henry	Crowley	1,194 acres	-	NR
36	Chatfield Reservoir	Jefferson	1,150 acres	-	B
37	Vega Reservoir	Mesa	1,109 acres	-	D
38	Ridgway Reservoir	Ouray	1,109 acres	-	C
39	Steamboat Lake	Routt	1,056 acres	-	D
40	Ruedi Reservoir	Eagle	1,031 acres	-	NR
41	Platoro Reservoir	Conejos	1,000 acres	-	NR
42	Neeskah Reservoir	Kiowa	915 acres	-	NR
43	Cheesman Lake	Douglas	885 acres	-	NR
44	Cherry Creek Reservoir Top	Arapahoe	852 acres	-	NR
45	Windsor Reservoir	Weld	852 acres	-	NR
46	Stagecoach Lake	Routt	819 acres	-	D
47	Rio Grande Reservoir	Hinsdale	809 acres	-	NR
48	Electra Lake	La Plata	804 acres	-	NR
49	San Luis Lake	Alamosa	798 acres	-	NR
50	Morrow Point Reservoir	Gunnison	775 acres	-	NR

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Frequently Asked Questions

What is the largest lake in Colorado?

Blue Mesa Reservoir, at 9,180 acres, in Gunnison County. Navajo Reservoir is larger at 19,000 acres. Straddles the Colorado-New Mexico line. Navajo Dam and the bulk of the pool are in New Mexico, so it is not a Colorado lake even though the upper end reaches Archuleta County (USACE NID NM00120: 19,000 acres). Source: Bureau of Reclamation (Aspinall Unit) / NPS Curecanti NRA / USACE National Inventory of Dams, 2026-07-30.

How is lake surface area measured?

Surface area comes from state DNR lake surveys and, for reservoirs, US Army Corps of Engineers (USACE) National Inventory of Dams records. Area is reported in acres at normal pool level. Reservoirs rise and fall with management and drought, so their listed area is the long-term normal rather than a single-day reading.

Are Colorado's largest lakes natural or reservoirs?

Of the top 50 Colorado lakes by area, 31 sit on a dammed river (reservoirs) and 19 are natural basins. Glacial states (MN, WI, MI, NY) skew natural; plains and southern states (MO, IA, ND, OH) skew toward reservoirs built for water supply, flood control, and recreation.

Do larger lakes have better water quality?

Not reliably. Quality varies more within a big lake than between lakes — a large lake can have a clean, deep main basin and a murky, algae-prone bay fed by a tributary, so one grade can mask wide swings. Depth, watershed land use, and how fast the lake flushes matter far more than raw surface area.

How big is the typical Colorado lake in this ranking?

Across the top 50 Colorado lakes by surface area, the median is 1,788 acres (Turquoise Reservoir). This list is biased toward the biggest waters; the typical Colorado lake is far smaller.

Where to stay near Colorado's largest lakes

Planning a trip? Jump to live cabin, resort, and hotel availability near Colorado's biggest lakes.

Deepest lakes in Colorado →Cleanest lakes in Colorado →Largest lakes (all states) →All Colorado lakes →