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LakeQuality

An oligotrophic lake is what most people picture when they think of pristine northern lake country: clarity to depth, no algal scum, cold water that holds dissolved oxygen all the way to the bottom even in August. Across New Mexico, 6 lakes register as oligotrophic — 0% of them break 50 feet of depth, which is the structural condition that underwrites the trophic class. Without depth and a low-nutrient watershed, oligotrophy is hard to sustain.

On our A–F scale, oligotrophic lakes almost always pull an A or B — the same low-nutrient conditions that produce the trophic class also produce the high grade.

#LakeCountyGradeClarityDepthTSI
1Heron Lake Deep DamRio ArribaC3.7 ft-49
2Grindstone Canyon Reservoir DeepLincolnC9 ft-46
3Mescalero Lake DeepOteroC--46
4Mescalero Lake ShallowOteroC--48
5Silver Lake DeepOteroC--47
6Silver Lake ShallowOteroD--49

Source: EPA National Aquatic Resource Surveys, 2026.