Lakes / Montana / Largest Lakes in Montana

Largest Lakes in Montana

Ranked by surface area, from Montana Fish, Wildlife & Parks lake data. Flowages and reservoirs count here - size is size - and each is labeled in its own record.

#	Lake	County	Surface Area	Max Depth
1	Fort Peck Lake	Valley	233,053 acres	-
2	Flathead Lake	Lake	122,132 acres	About 380 ft
3	Canyon Ferry Lake	Broadwater	32,773 acres	About 170 ft
4	Lake Koocanusa	Lincoln	28,723 acres	-
5	Hungry Horse Reservoir	Flathead	23,577 acres	-
6	Lake Elwell	Liberty	14,842 acres	About 150 ft
7	Hebgen Lake	Gallatin	12,564 acres	About 80 ft
8	Bighorn Lake	Big Horn	12,422.5 acres	About 440 ft
9	Medicine Lake	Sheridan	8,931 acres	-
10	Noxon Reservoir	Sanders	7,592 acres	-
11	Lake McDonald	Flathead	6,867 acres	-
12	Clark Canyon Reservoir	Beaverhead	4,815 acres	About 91 ft
13	Lima Reservoir	Beaverhead	4,422 acres	-
14	Nelson Reservoir	Phillips	4,115 acres	-
15	Saint Mary Lake	Glacier	3,933 acres	-
16	Ennis Lake	Madison	3,692 acres	-
17	Holter Lake	Lewis and Clark	3,667 acres	-
18	Lake Bowdoin	Phillips	3,659.5 acres	-
19	Lake Frances	Pondera	3,618 acres	About 43 ft
20	Whitefish Lake	Flathead	3,315 acres	About 220 ft
21	Swan Lake	Lake	3,269 acres	About 120 ft
22	Bynum Reservoir	Teton	3,205 acres	-
23	Hauser Lake	Lewis and Clark	3,200 acres	About 65 ft
24	Fresno Reservoir	Hill	3,185 acres	-
25	Little Bitterroot Lake	Flathead	2,970 acres	About 260 ft
26	Upper Red Rock Lake	Beaverhead	2,948 acres	About 5 ft
27	Ashley Lake	Flathead	2,850 acres	About 200 ft
28	Cabinet Gorge Reservoir	Sanders	2,848 acres	-
29	Georgetown Lake	Granite	2,818 acres	About 25 ft
30	Benton Lake	Cascade	2,699.9 acres	-
31	Freezeout Lake	Teton	2,596 acres	-
32	Big Lake	Stillwater	2,583 acres	-
33	Lower Red Rock Lake	Beaverhead	2,219 acres	-
34	Lower Saint Mary Lake	Glacier	2,177 acres	-
35	Tongue River Reservoir	Big Horn	2,112 acres	-
36	Lake Helena	Lewis and Clark	2,073 acres	About 12 ft
37	Deadmans Basin Reservoir	Wheatland	1,954 acres	-
38	Wild Horse Lake	Petroleum	1,929.1 acres	-
39	Bowman Lake	Flathead	1,722 acres	-
40	Kintla Lake	Flathead	1,665 acres	-
41	Pablo Reservoir	Lake	1,650 acres	-
42	McGregor Lake	Flathead	1,522 acres	About 220 ft
43	Pishkun Reservoir	Teton	1,518 acres	About 78 ft
44	Lake Mary Ronan	Lake	1,513 acres	About 40 ft
45	Kingsbury Lake	Chouteau	1,463.6 acres	-
46	Duck Lake	Glacier	1,446 acres	-
47	Lake Sherburne	Glacier	1,368 acres	About 60 ft
48	Willow Creek Reservoir	Lewis and Clark	1,314 acres	About 50 ft
49	Gibson Reservoir	Lewis and Clark	1,289 acres	About 165 ft
50	Homestead Lake	Roosevelt	1,261.6 acres	-
51	Dry Lake Unit	Phillips	1,224.2 acres	-
52	Lake Mason	Musselshell	1,220 acres	-
53	Big Lake	Chouteau	1,212.5 acres	-
54	Placid Lake	Missoula	1,212 acres	About 93 ft
55	Tally Lake	Flathead	1,211 acres	About 450 ft
56	Ninepipe Reservoir	Lake	1,203 acres	-
57	Bull Lake	Lincoln	1,162 acres	About 60 ft
58	Aloe Lake	Toole	1,121 acres	-
59	Logging Lake	Flathead	1,113 acres	-
60	Weigand Reservoir	Phillips	1,097.3 acres	-
61	Seeley Lake	Missoula	1,031 acres	About 120 ft
62	Alkali Lake	Pondera	1,011.6 acres	-
63	Upper Waterton Lake	Glacier	1,009 acres	-
64	Big Salmon Lake	Flathead	972 acres	-
65	Thompson Falls Reservoir	Sanders	969 acres	-
66	Martinsdale Reservoir	Meagher	947 acres	-
67	Ruby River Reservoir	Madison	941 acres	-
68	Lake Como	Ravalli	911 acres	-
69	Quartz Lake	Flathead	869 acres	-
70	Benton Lake	Cascade	854.9 acres	-
71	Lindbergh Lake	Missoula	815 acres	About 120 ft
72	Benton Lake	Cascade	766.1 acres	-
73	Mission Lake	Glacier	755 acres	-
74	White Lake	Chouteau	754.6 acres	-
75	Cooney Reservoir	Carbon	733 acres	-
76	Lonesome Lake	Chouteau	727.7 acres	-
77	Capeneys Lake	Sheridan	722.5 acres	-
78	Four Horns Lake	Glacier	719 acres	-
79	Lower Two Medicine Lake	Glacier	718.7 acres	-
80	Willow Creek Reservoir	Madison	713 acres	-
81	Echo Lake	Flathead	695 acres	About 70 ft
82	Upper Holter Lake	Lewis and Clark	695 acres	-
83	Kicking Horse Reservoir	Lake	657 acres	-
84	Goose Lake	Sheridan	655.8 acres	-
85	Salmon Lake	Missoula	631 acres	About 65 ft
86	Buffalo Lake	Glacier	615.1 acres	-
87	Earthquake Lake	Madison	612 acres	About 120 ft
88	Cliff Lake	Madison	608 acres	-
89	Whitetail Reservoir	Jefferson	603 acres	-
90	Upper Stillwater Lake	Flathead	592 acres	-
91	Dickey Lake	Lincoln	585 acres	About 70 ft
92	Frenchman Reservoir	Phillips	573 acres	-
93	Painted Rocks Lake	Ravalli	564.9 acres	-
94	Benton Lake	Cascade	560.2 acres	-
95	Middle Thompson Lake	Lincoln	557 acres	About 160 ft
96	Helena Valley Regulating Reservoir	Lewis and Clark	553 acres	-
97	Mud Lake	Hill	546.3 acres	-
98	Lodge Grass Storage Reservoir	Big Horn	534 acres	-
99	North Chinook Reservoir	Blaine	523.1 acres	-
100	Glass Lindsay Lakes Lower Reservoir	Sweet Grass	522.4 acres	-

Showing the top 100 of 1,694 counted lakes. Search above, or browse by county on the Montana page, for the full inventory.

Source: Montana Fish, Wildlife & Parks lake data. Verified October 30, 2026. New lakes are added as their records are verified - rankings update with every addition.