Updated Aug 2026
New Mexico Lake Water Quality
Water quality grades for 73 monitored lakes across 22 counties.
73 New Mexico lakes carry a grade. Most of the input data flows through monitoring run by the New Mexico Environment Department, which feeds state, federal, and volunteer measurements into the EPA Water Quality Portal. Only about 5% of New Mexico's lakes pull an A grade — the smaller, agricultural-watershed lakes that dominate the dataset tend to carry persistent nutrient loads. 8% of lakes fall in the D or F brackets.
The state's dominant trophic class is oligotrophic: clear, nutrient-poor, slow-growing. These lakes are also the most sensitive to disturbance — the same volume that buffers them against nutrients also slows recovery if those nutrients arrive in quantity. San Miguel ranks highest on average county grade (A). Sierra sits lowest. With only 22 counties in the state, the cross-county spread is narrower than the within-county spread for most lakes.
Grade Distribution
All 73 New Mexico lakes in the index: 18 (24.7%) carry an A–F grade and 55 (75.3%) are not rated, because they lack enough recent nutrient or algae sampling to support a letter.
Where to stay near New Mexico
Top-rated places to stay near New Mexico
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Top-Graded New Mexico Lakes
The highest water-quality grades in New Mexico — clarity, depth, and A-F grade at a glance.
Lake Map
Explore New Mexico Lakes
New Mexico reports, fishing & travel
Reservoirs in New Mexico
View all 45 reservoirs →45 of 73 New Mexico lakes (62%) are man-made reservoirs in the USACE National Inventory of Dams. 42 carry a High or Significant hazard rating. The oldest matched dam dates to 1900.
EPA-Impaired Lakes in New Mexico
View all 42 impaired lakes →42 of 73 New Mexico lakes (58%) are officially listed as impaired under Clean Water Act §303(d) in the most recent EPA ATTAINS reporting cycle. 5 have an approved Total Maximum Daily Load (TMDL) restoration plan.
New Mexico Fishing & Recreation
Licenses, regulations, records, and where to fish across New Mexico.
Counties
All 22 New Mexico counties, ranked by average lake water quality. Compare them against every county nationwide in the county rankings, browse the full directory of graded lakes, or pick a different state.
Cleanest New Mexico Lakes
18 lakes18 graded lakes
| # | Lake | County | Grade | Clarity | Trophic | Access |
|---|---|---|---|---|---|---|
| 1 | AAbiquiu Reservoir | Rio Arriba | A | 3.3 ft | Mesotrophic | Not recorded |
| 2 | AAbiquiu Reservoir Chama R Inlet | Rio Arriba | A | 3.3 ft | Mesotrophic | ✓ Public |
| 3 | AConchas Reservoir | San Miguel | A | 8.9 ft | Mesotrophic | ✓ Public |
| 4 | ASanta Rosa L Dp Sta Midchannel Buoy Lake | Guadalupe | A | 1.6 ft | Mesotrophic | ✓ Public |
| 5 | CHeron Lake Deep Dam | Rio Arriba | C | 3.7 ft | Oligotrophic | ✓ Public |
| 6 | CGrindstone Canyon Reservoir Deep | Lincoln | C | 9 ft | Oligotrophic | Not recorded |
| 7 | CHeron Lake Shallow | Rio Arriba | C | 2.5 ft | Mesotrophic | Not recorded |
| 8 | CSandia Lakes Recreation Area | Sandoval | C | 1.3 ft | Eutrophic | Not recorded |
| 9 | CSandia Lakes | Sandoval | C | 1.2 ft | Eutrophic | Not recorded |
| 10 | CMescalero Lake Deep | Otero | C | No recent samples | Oligotrophic | ✓ Public |
| 11 | CMescalero Lake Shallow | Otero | C | No recent samples | Oligotrophic | Not recorded |
| 12 | CSilver Lake Deep | Otero | C | No recent samples | Oligotrophic | Not recorded |
| 13 | DAlto Lake | Lincoln | D | 8.9 ft | Mesotrophic | Not recorded |
| 14 | DE Butte Lake | Sierra | D | 3.6 ft | Eutrophic | ✓ Public |
| 15 | DSilver Lake Shallow | Otero | D | No recent samples | Oligotrophic | Not recorded |
| 16 | DGrindstone Caynon Reservoir Inlet | Lincoln | D | No recent samples | Eutrophic | Not recorded |
| 17 | FHopewell Lake | Rio Arriba | F | 3.9 ft | Hypereutrophic | Not recorded |
| 18 | FCaballo Lake | Sierra | F | 1.8 ft | Hypereutrophic | ✓ Public |
New Mexico Lakes Needing Attention
18 lakes18 graded lakes
| # | Lake | County | Grade | Clarity |
|---|---|---|---|---|
| 1 | FCaballo Lake | Sierra | F | 1.8 ft |
| 2 | FHopewell Lake | Rio Arriba | F | 3.9 ft |
| 3 | DGrindstone Caynon Reservoir Inlet | Lincoln | D | No recent samples |
| 4 | DSilver Lake Shallow | Otero | D | No recent samples |
| 5 | DE Butte Lake | Sierra | D | 3.6 ft |
| 6 | DAlto Lake | Lincoln | D | 8.9 ft |
| 7 | CSilver Lake Deep | Otero | C | No recent samples |
| 8 | CMescalero Lake Shallow | Otero | C | No recent samples |
| 9 | CMescalero Lake Deep | Otero | C | No recent samples |
| 10 | CSandia Lakes | Sandoval | C | 1.2 ft |
| 11 | CSandia Lakes Recreation Area | Sandoval | C | 1.3 ft |
| 12 | CHeron Lake Shallow | Rio Arriba | C | 2.5 ft |
| 13 | CGrindstone Canyon Reservoir Deep | Lincoln | C | 9 ft |
| 14 | CHeron Lake Deep Dam | Rio Arriba | C | 3.7 ft |
| 15 | ASanta Rosa L Dp Sta Midchannel Buoy Lake | Guadalupe | A | 1.6 ft |
| 16 | AConchas Reservoir | San Miguel | A | 8.9 ft |
| 17 | AAbiquiu Reservoir Chama R Inlet | Rio Arriba | A | 3.3 ft |
| 18 | AAbiquiu Reservoir | Rio Arriba | A | 3.3 ft |
Lake Match
Which lake suits how you actually use one?
Six questions — swimming, fishing, quiet, cabins, drive time — and a shortlist of graded lakes that fit, with the water quality behind each one.
Source: EPA National Aquatic Resource Surveys and the EPA Water Quality Portal.
More on lake water quality
The top-graded lake in every state we cover, picked grade-first with water clarity as the tie-breaker — plus the states whose winner is still not clean.
State-by-state Secchi champions: the clearest measured lake in each U.S. state we grade, which is not the same as the cleanest nutrient grade.
A data snapshot of the lakes we grade: how the A–F distribution breaks down, the clearest and the greenest states, and where the water is improving.
How lakes are graded A–F on nutrients and algae using EPA ecoregion condition classes, what each letter means in the water, and why an A is not a clearance.