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LakeQuality
Late afternoon sun over Slim Lake, scattering a bright path across wind-textured water
D

Powell County Lake Quality

Montana, 20 lakes, average grade D (Nutrient-rich)

There are 20 monitored lakes in Powell County. The mix is varied enough that the county-level average tells you the broad strokes, not the choose-this-cabin specifics. 1 of those lake carry an A–F grade. The county-level summary describes that subset, not every water body listed. The county-wide average grade is D — water quality issues are persistent across most of the monitored basins. 0 lakes fall into the F bracket outright.

The county's lakes lean shallow, which makes the grades sensitive to wind, sediment-resuspension, and any nutrient inputs from the watershed. The cleanest lake on the books is Elbow Lake (D); the most-stressed is Elbow Lake (D).

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Top-rated places to stay near Powell County

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All Lakes in Powell County

20 lakes · 1 graded, 19 not rated1 graded lake · 19 not rated, hidden

#LakeGradeClarityPhosphorusAlgaeTrophicAccess
1DElbow LakePowellDNo recent samples11.6 µg/L4.2 µg/LNo recent samplesNot recorded
NRMountain Ben LakePowellNRNo recent samplesNo recent samplesNo recent samplesNo recent samplesNot recorded
NRUpper Elliot LakePowellNRNo recent samplesNo recent samplesNo recent samplesNo recent samplesNot recorded
NRLower Elliot LakePowellNRNo recent samplesNo recent samplesNo recent samplesNo recent samplesNot recorded
NRLois LakePowellNRNo recent samplesNo recent samplesNo recent samplesNo recent samplesNot recorded
NRNevada LakePowellNRNo recent samplesNo recent samplesNo recent samplesNo recent samplesNot recorded
NRDoney LakePowellNRNo recent samplesNo recent samplesNo recent samplesNo recent samplesNot recorded
NRRock Creek LakePowellNRNo recent samplesNo recent samplesNo recent samplesNo recent samplesNot recorded
NRBrowns LakePowellNRNo recent samplesNo recent samplesNo recent samplesNo recent samplesNot recorded
NRKleinschmidt LakePowellNRNo recent samplesNo recent samplesNo recent samplesNo recent samplesNot recorded
NREvans LakePowellNRNo recent samplesNo recent samplesNo recent samplesNo recent samplesNot recorded
NRWales Creek ReservoirPowellNRNo recent samplesNo recent samplesNo recent samplesNo recent samplesNot recorded
NRUpsata LakePowellNRNo recent samplesNo recent samplesNo recent samplesNo recent samples✓ Public
NRBandy ReservoirPowellNRNo recent samplesNo recent samplesNo recent samplesNo recent samplesNot recorded
NRJames LakePowellNRNo recent samplesNo recent samplesNo recent samplesNo recent samplesNot recorded
NRShoup LakePowellNRNo recent samplesNo recent samplesNo recent samplesNo recent samplesNot recorded
NRJones LakePowellNRNo recent samplesNo recent samplesNo recent samplesNo recent samplesNot recorded
NRLahrity LakePowellNRNo recent samplesNo recent samplesNo recent samplesNo recent samplesNot recorded
NRDoney LakePowellNRNo recent samplesNo recent samplesNo recent samplesNo recent samplesNot recorded
NRCoopers LakePowellNRNo recent samplesNo recent samplesNo recent samplesNo recent samplesNot recorded

NR = not rated: there is not enough recent sampling to support a letter. That is EPA Integrated Reporting Category 3 (insufficient information), not a failing grade. How grading works.

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See how Powell County stacks up in the national county water-quality rankings, or browse the full directory of graded lakes across all United States (49 states), Canada (Ontario, Québec, Nova Scotia, British Columbia and Newfoundland and Labrador), and 38 other country hubs..

Source: EPA National Aquatic Resource Surveys, 2026.