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

Cleanest Lakes in Boulder County, Colorado

Lake Isabelle in Boulder County leads the rankings with a water quality grade of NR. Below are the top 35 cleanest monitored lakes in Boulder County, Colorado, ranked by EPA water quality score.

Ranked List

#LakeCountyGradeClarityPhosphorusAlgae
1Lake IsabelleBoulderNR---
2Long LakeBoulderNR---
3Albion LakeBoulderNR---
4Goose LakeBoulderNR---
5Island LakeBoulderNR---
6Boulder ReservoirBoulderNR---
7Left Hand Valley ReservoirBoulderNR---
8Sixmile ReservoirBoulderNR---
9Hayden LakeBoulderNR---
10Leggett and Hillcrest ReservoirBoulderNR---
11Harper LakeBoulderNR---
12Base Line ReservoirBoulderNR---
13Marshall LakeBoulderNR---
14Waneka ReservoirBoulderNR---
15Barker ReservoirBoulderNR---
16Gross ReservoirBoulderNR---
17Gold LakeBoulderNR---
18Silver LakeBoulderNR---
19Left Hand ReservoirBoulderNR---
20Beaver ReservoirBoulderNR---
21Button Rock ReservoirBoulderNR---
22Allens LakeBoulderNR---
23Foothills ReservoirBoulderNR---
24Clover Basin ReservoirBoulderNR---
25McIntosh LakeBoulderNR---
26Lagerman ReservoirBoulderNR---
27Dodd ReservoirBoulderNR---
28Gaynor LakeBoulderNR---
29Terry LakeBoulderNR---
30Crystal LakeBoulderNR---
31Walker ReservoirBoulderNR---
32Divide ReservoirBoulderNR---
33Ish ReservoirBoulderNR---
34Burch LakeBoulderNR---
35McCall LakeBoulderNR---

More Answers for Boulder County, Colorado

All lakes in Boulder County →Cleanest lakes in Colorado →

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