Missoula County Lake Quality

Montana, 60 lakes, average grade A (Excellent)

Missoula County has 60 graded lakes, enough that within-county variation matters as much as the county average. Some are deep glacial basins, others are shallow agricultural-watershed waters, and the grade distribution reflects that mix. The county's average grade is A — among the cleanest in {{stateName}}. 42 lakes pull an A on their own, and almost none fall into the D or F brackets.

Most of the county's monitored lakes are shallow — under 50 feet — which means wind keeps the water column mixed all summer and sediment-bound phosphorus releases back into the surface layer whenever the bottom is disturbed. Big Sky Lake South Hole (A) is the cleanest in the county.

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Quick Answers for Missoula County

Cleanest lakes in Missoula County →Cleanest lakes in Montana →Safest swimming lakes in Montana →

Planning a trip? Check special fishing regulations for Big Sky Lake South Hole — or check the official Montana fishing regulations.

All Lakes in Missoula County

Rank	Lake	Grade	Clarity	Phosphorus
1	Big Sky Lake South Hole	A	17.7 ft	9.6 µg/L
2	Nla Lake	A	41.9 ft	3.7 µg/L
3	Lake Alva Mid-Lake Deep	A	21.6 ft	6.6 µg/L
4	Salmon Lake South Basin	A	16.6 ft	-
5	Seeley Lake Middle Basin	A	15.4 ft	8.1 µg/L
6	Placid Lake North Finger Outlet Hole	A	16.8 ft	-
7	Placid Lake Midlake Hole	A	16.5 ft	8 µg/L
8	Lake Inez North Hole	A	17.4 ft	-
9	Salmon Lake Mid-South Basin	A	16.4 ft	-
10	Lake Inez South Hole	A	17.8 ft	12.1 µg/L
11	Seeley Lake North Basin	A	16.8 ft	-
12	Clearwater Lake Deep	A	28.6 ft	-
13	Rainy Lake Deep	A	18.9 ft	-
14	Salmon Lake Mid-North Basin	A	17 ft	11.3 µg/L
15	Lindbergh Lake	A	26.5 ft	-
16	Holland Lake	A	30.5 ft	-
17	Holland Lake	A	-	4.6 µg/L
18	Lindbergh Lake	A	-	4 µg/L
19	Lake Inez Off Helms Rd S End of Lake	A	-	4.9 µg/L
20	Lake Inez Off Rana Drive Upper W Side of Lake	A	-	6 µg/L
21	Seeley Lake	A	-	6 µg/L
22	Salmon Lake	A	-	7.5 µg/L
23	Placid Lake Off Placid Lake Rd S	A	-	7.8 µg/L
24	Seeley Lake	A	-	5.2 µg/L
25	Salmon Lake	A	-	7.7 µg/L
26	Seeley Lake	A	-	6 µg/L
27	Seeley Lake	A	-	4.9 µg/L
28	Seeley Lake	A	-	5.5 µg/L
29	Placid Lake	A	-	10.7 µg/L
30	Placid Lake Off Placid Lake Rd N	A	-	7.3 µg/L
31	Seeley Lake	A	-	3.8 µg/L
32	Salmon Lake	A	-	7.6 µg/L
33	Clearwater River Lake	A	-	12 µg/L
34	Seeley Lake	A	-	5.6 µg/L
35	Seeley Lake	A	-	5.8 µg/L
36	Seeley Lake	A	-	5.7 µg/L
37	Inez Lake	A	-	6.6 µg/L
38	Big Sky Lake	A	-	10.2 µg/L
39	Inez_deep Lake	A	-	16.3 µg/L
40	Alva Lake	A	-	4.7 µg/L
41	Alva_deep Lake	A	-	10.5 µg/L
42	Seeley Lake South Basin	A	14.4 ft	17.4 µg/L
43	Salmon Lake North Basin	B	14.7 ft	-
44	Big Sky_deep Lake	F	-	181 µg/L