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LakeQuality
Pink and orange afterglow over the treeline on Slim Lake after sunset

Updated August 2026

The State of Nevada's Lakes 2026

Of 44 lakes in Nevada, 18.8% earn a water-quality grade of A or B and 50% score D or F (average grade C). Illipah Reservoir is the cleanest; 22 lakes (50%) are on an official impaired-waters list.

Data Report

44
Monitored lakes graded
C
Average grade
18.8%
Grade A or B
50%
On impaired list

Nevada grade distribution

A
B
C
D
F
A: 2 (12.5%)B: 1 (6.3%)C: 5 (31.3%)D: 6 (37.5%)F: 2 (12.5%)

Cleanest lakes in Nevada

Highest combined water-quality score, 2026.

  1. 1.BIllipah Reservoir — White Pine County30 µg/L P · 2 µg/L chl-a
  2. 2.CRye Patch Reservoir — Pershing County120 µg/L P · 3 µg/L chl-a
  3. 3.COnion Valley Reservoir @ Dam — Humboldt County50 µg/L P · 5 µg/L chl-a
  4. 4.DSheep Creek Lake — Elko County6.2 ft clarity · 83 µg/L P · 20 µg/L chl-a
  5. 5.DBilly Shaw Lake — Elko County34 µg/L P · 15 µg/L chl-a
  6. 6.DMountain View Lake — Elko County40 µg/L P · 17 µg/L chl-a
  7. 7.FWildhorse Reservoir — Elko County5.9 ft clarity · 107 µg/L P · 67 µg/L chl-a
  8. 8.FKnott Creek Reservoir — Humboldt County145 µg/L P · 59 µg/L chl-a

Most-polluted lakes

Lowest combined water-quality score among monitored lakes.

  1. 1.FWildhorse Reservoir — Elko County5.9 ft clarity · 107 µg/L P · 67 µg/L chl-a
  2. 2.FKnott Creek Reservoir — Humboldt County145 µg/L P · 59 µg/L chl-a
  3. 3.DSheep Creek Lake — Elko County6.2 ft clarity · 83 µg/L P · 20 µg/L chl-a
  4. 4.DBilly Shaw Lake — Elko County34 µg/L P · 15 µg/L chl-a
  5. 5.DMountain View Lake — Elko County40 µg/L P · 17 µg/L chl-a
  6. 6.CRye Patch Reservoir — Pershing County120 µg/L P · 3 µg/L chl-a
  7. 7.COnion Valley Reservoir @ Dam — Humboldt County50 µg/L P · 5 µg/L chl-a
  8. 8.BIllipah Reservoir — White Pine County30 µg/L P · 2 µg/L chl-a

Worst algae hotspots

Highest measured chlorophyll-a (algae) concentration.

  1. 1.FWildhorse Reservoir — Elko County67 µg/L chlorophyll-a
  2. 2.NRSheep Creek Middle Reservoir — Elko County64 µg/L chlorophyll-a
  3. 3.FKnott Creek Reservoir — Humboldt County59 µg/L chlorophyll-a
  4. 4.CSpooner Lake — Douglas County41 µg/L chlorophyll-a
  5. 5.NRWillow Creek Reservoir East — Elko County27 µg/L chlorophyll-a

Trending lakes

Improving

  1. 1.BIllipah Reservoir — White Pine County
  2. 2.CRye Patch Reservoir — Pershing County
  3. 3.CSquaw Creek Reservoir — Washoe County
  4. 4.DMountain View Lake — Elko County
  5. 5.DWall Canyon Reservoir — Washoe County
  6. 6.FWildhorse Reservoir — Elko County
  7. 7.NRWillow Creek Reservoir East — Elko County
  8. 8.NRWillow Creek Reservoir West — Elko County

Declining

  1. 1.DWalker Lake — Mineral County
  2. 2.DSheep Creek Lake — Elko County
  3. 3.DBilly Shaw Lake — Elko County
  4. 4.CBoulder Reservoir — Washoe County
  5. 5.COnion Valley Reservoir @ Dam — Humboldt County
  6. 6.CSpooner Lake — Douglas County
  7. 7.AComins Reservoir — White Pine County
  8. 8.ALake Tahoe — Douglas County

Impaired waters in Nevada

22 lakes appear on the EPA/state 303(d) impaired-waters list (21 formally listed, 1 with a cleanup plan/TMDL).

Metals (other than mercury) · 18Nutrients (phosphorus, nitrogen) · 16Oxygen depletion (low DO) · 11Temperature · 8Mercury · 6Turbidity · 6pH / acidity · 6Salinity / chlorides · 4

Explore Nevada lakes

Lake Fishing Forecast

Species activity outlook by water temperature and season

Nevada Lake Trips

Where to stay at Nevada's top lakes, each with its grade

Grades combine total phosphorus, total nitrogen, chlorophyll-a, and turbidity from the EPA Water Quality Portal and state agencies. See the full methodology, the national State of America’s Lakes report, or all Nevada lakes.

Cite this report: LakeQuality, “The State of Nevada's Lakes 2026”.