Cleanest Lakes in New Mexico: Top 25 Ranked by Water Quality
The single cleanest lake in New Mexico is Nla Lake, with the highest combined water quality score in our 2026 dataset (grade A). Cleanliness is measured by Secchi depth (clarity), total phosphorus, and chlorophyll-a — all sourced from EPA Water Quality Portal and state agency sampling. The full top 25 ranked list appears below.
Filtered to remove lakes with limited data (<3 sampling years). Sorted by overall water quality score.
Ranking the cleanest {{stateName}} lakes means picking the basins that score high on all three water-quality dimensions, not just one. Nla Lake leads the list with a grade of A, with Nla Lake close behind.
The top of the cleanest-lakes list is dominated by deep, glacial, cold-water basins — the same basins that produce the A-grade bracket overall. The pattern is not coincidence: depth and watershed land-use are the dominant inputs to water-clarity and nutrient-loading both.
| Rank | Lake | County | Grade | Clarity | Phosphorus | Chlorophyll-a | Area |
|---|---|---|---|---|---|---|---|
| 1 | Nla Lake | San Juan | A | 14.4 ft | 13.9 µg/L | 0.3 µg/L | - |
| 2 | Nla Lake | San Miguel | A | 2.3 ft | 21.7 µg/L | 2.7 µg/L | - |
| 3 | Nla Lake | San Miguel | A | 8.2 ft | 17.7 µg/L | 2.6 µg/L | - |
| 4 | Nla Lake | Colfax | A | 10.5 ft | 24.8 µg/L | 2.4 µg/L | - |
| 5 | Nla Lake | Colfax | A | 8.2 ft | 23.7 µg/L | 1.9 µg/L | - |
| 6 | Fenton Lake | Sandoval | A | 7.9 ft | 14 µg/L | 5.4 µg/L | - |
| 7 | Figure Eight Lake | Chaves | A | 6.9 ft | 17 µg/L | 3 µg/L | - |
| 8 | Heron Lake Deep Dam | Rio Arriba | B | 3.7 ft | 29 µg/L | 1.6 µg/L | - |
| 9 | Abiquiu Reservoir | Rio Arriba | B | 3.3 ft | 40 µg/L | 2.7 µg/L | - |
| 10 | Abiquiu Reservoir Chama R Inlet | Rio Arriba | B | 3.3 ft | 36 µg/L | 2.4 µg/L | - |
| 11 | Grindstone Canyon Reservoir Deep | Lincoln | B | 9 ft | 38 µg/L | 2 µg/L | - |
| 12 | Heron Lake Shallow | Rio Arriba | B | 2.5 ft | 32 µg/L | 2.1 µg/L | - |
| 13 | Mescalero Lake Deep | Otero | B | — | 50 µg/L | 1.2 µg/L | - |
| 14 | Mescalero Lake Shallow | Otero | B | — | 55 µg/L | 1.6 µg/L | - |
| 15 | Silver Lake Shallow | Otero | B | — | 50 µg/L | 1.9 µg/L | - |
| 16 | Nla Lake | Rio Arriba | B | 3.9 ft | 43.8 µg/L | 5.4 µg/L | - |
| 17 | Nla Lake | Mora | B | 1 ft | 34 µg/L | 6.5 µg/L | - |
| 18 | Brantley Reservoir Shallow | Eddy | B | 2.1 ft | 40 µg/L | 4.7 µg/L | - |
| 19 | Silver Lake Deep | Otero | B | — | 80 µg/L | 1.3 µg/L | - |
| 20 | Nla Lake | Quay | C | 3.9 ft | 24000 µg/L | 1.7 µg/L | - |
| 21 | Nla Lake | San Juan | C | 10.5 ft | 17000 µg/L | 1.2 µg/L | - |
| 22 | Nla Lake | McKinley | C | 5.7 ft | 76084.2 µg/L | 2.8 µg/L | - |
| 23 | Nla Lake | Rio Arriba | C | 19 ft | 56000 µg/L | 1.8 µg/L | - |
| 24 | Nla Lake | Taos | C | 8.2 ft | 8007.4 µg/L | 1.7 µg/L | - |
| 25 | Nla Lake | Rio Arriba | C | 3.3 ft | 36.9 µg/L | 8.7 µg/L | - |
Clearest lakes in New Mexico by water clarity
“Clearest” ranks by Secchi depth — how far you can see into the water — which can differ from the combined cleanliness score above. The clearest water in New Mexico is Nla Lake at 19 ft of Secchi visibility.
- 1. Nla Lake — 19 ft, Rio Arriba County
- 2. Navajo Reservoir — 16 ft, San Juan County
- 3. Perch Lake — 14.8 ft, Guadalupe County
- 4. Nla Lake — 14.4 ft, San Juan County
- 5. Navajo Reservoir la Jara Confluence — 13.5 ft, Rio Arriba County
Frequently Asked Questions
What is the cleanest lake in New Mexico?
Nla Lake has the highest water quality score in our 2026 New Mexico dataset (grade A), based on combined Secchi clarity, phosphorus, and chlorophyll-a measurements. Cleanliness here means low nutrient load, deep water clarity, and minimal algae — measured directly from EPA and state DNR samples.
What is the most polluted lake in New Mexico?
Among monitored New Mexico lakes, Bluewater Lake ranks among the most polluted by combined phosphorus and chlorophyll-a load. See our full ranking on the most-polluted-lakes trend page for state-by-state details.
Where in New Mexico has the cleanest water?
New Mexico's clearest waters are concentrated in deeper, lower-nutrient glacial basins with forested or low-agriculture watersheds. Among the current top-ranked lakes above, counties like Rio Arriba, Otero, and San Juan produce the highest-scoring lakes.
What is the clearest lake in New Mexico?
Nla Lake is the clearest lake in New Mexico by water clarity, with a Secchi depth of 19 feet — the deepest transparency in our 2026 dataset. "Clearest" ranks by Secchi depth (how far you can see into the water) specifically, while "cleanest" combines clarity with phosphorus and chlorophyll-a. See our full clearest-lakes ranking for New Mexico for the top 25 by Secchi clarity.
Are these lakes safe to swim in?
A and B grade lakes are typically safe for swimming under normal conditions. Chlorophyll-a below 10 µg/L means low risk of harmful algal blooms. Always check posted advisories before swimming — water quality changes seasonally, especially in late summer when blue-green algae bloom risk peaks.
How are these grades calculated?
Each lake is scored on three signals: Secchi depth (water clarity in feet), total phosphorus (nutrient load in µg/L), and chlorophyll-a (algae concentration in µg/L). Each gets a 0–100 sub-score relative to New Mexico state norms. The three sub-scores average into the overall score, which maps to an A–F letter grade. Methodology details live on our methodology page.
What are the top 5 cleanest lakes in the US?
There is no single national ranking of cleanest lakes — each state agency uses different metrics. Crater Lake (Oregon) is widely cited as the clearest US lake, with Secchi depths over 30 m. Lake Tahoe and Lake Superior are also top-tier nationally. Within New Mexico, the lakes ranked above are the top 25 by our standardized 2026 grading.
How we rank cleanest lakes
Cleanliness here means three things working together:
- Secchi clarity — how deep you can see into the water (in feet). Greater depth = clearer water = lower suspended sediment and algae.
- Total phosphorus — the nutrient that fuels algae. Lower phosphorus levels mean less algae growth potential.
- Chlorophyll-a — the green pigment in algae. Direct measurement of how much algae is currently in the water.
Each signal is normalized against New Mexico state norms and combined into a single 0–100 score. The lakes above are sorted by that combined score.Full methodology →
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Source: EPA National Aquatic Resource Surveys, 2026.