New Mexico reservoir · state assessment record
San Gregorio Lake
Assessment decisions reported by New Mexico to EPA under Clean Water Act sections 303(d) and 305(b), last assessed in the 2016 reporting cycle.
- 36
- Assessed acres
- Reservoir
- Water type
This waterbody in one line
San Gregorio Lake, a reservoir in New Mexico, is assessed as not supporting one or more designated uses, with one listed impairment cause in the state's most recent Integrated Report cycle (2016). By assessed acreage it sits below the national median by assessed acreage (38,628 lakes); its impairment list is among the longest nationally (one listed cause vs 23,610 assessed lakes). New Mexico rules it not supporting for high quality coldwater aquatic life, while other aquatic-life uses are supported.
- Not Supporting
- overall status
- P47
- Assessed size nationally
- P20
- Shorter cause list
- Not Supporting
- aquatic-life or related
Assessment verdicts are the state agency's decisions as reported to EPA ATTAINS; PlainLakes renders them without modification.
A composite of this record's EPA ATTAINS designated-use verdicts, filed impairment count, and assessment currency, weighted and benchmarked against the national corpus of assessed active waterbodies. This is a water-quality standing, not a human-recreation or property-value judgment, and dimensions with no filed verdict drop out rather than count against the score.
San Gregorio Lake against the ATTAINS register
Paragraphs are selected by this unit's percentiles and use matrix: different lakes lead with different dimensions. Figures are ATTAINS / portal register arithmetic, not advice.
The signature stat: in-state cause rank
Inside New Mexico, cause-list rank 37 of 58 is mid-pack, the state peer table is not driven by an extreme list length here.
Not one verdict, several
This record splits: Not Supporting on aquatic life, Fully Supporting on recreation. The divergence is inside the designated-use matrix, not a single all-or-nothing label.
San Gregorio Lake: Category 5, TMDL still owed
Category 5 is the Integrated Report band where a TMDL (or equivalent) is still expected for San Gregorio Lake. Read the listed causes and any cleanup actions filed beside them before treating the overall status tile as a finished restoration story.
Overall status: not supporting
The filer's overall status for San Gregorio Lake is Not Supporting. That tile summarizes the assessment unit; the designated-use rows and cause list are the evidence behind it.
Mid-pack inside New Mexico
Size rank 38 of 58 inside New Mexico is mid-pack; the national percentile is the better scale comparison for this unit.
According to the U.S. Environmental Protection Agency's ATTAINS program, New Mexico carries 176 filed lake-type waterbodies in the August 2026 extract, and this page renders the assessment record EPA assigned to San Gregorio Lake without modification. See our methodology for reporting-unit limits and gauge linking rules.
The record
Designated-use assessments
Fully Supporting and Not Supporting are the state's definitive verdicts; other entries mean the use was not conclusively assessed in this cycle.
| Designated use | Group | Verdict |
|---|---|---|
| Domestic Water Supply | Drinking-water supply designation | Fully Supporting |
| High Quality Coldwater Aquatic Life | Aquatic-life or related | Not Supporting |
| Irrigation | Other | Fully Supporting |
| Livestock Watering | Other | Fully Supporting |
| Primary Contact | Recreation | Fully Supporting |
| Wildlife Habitat | Aquatic-life or related | Fully Supporting |
The record
Listed impairment causes
Causes the state listed as impairing designated uses of this reservoir, with the cycle each was first listed and the Clean Water Act action recorded against it.
| Cause | Affected uses | First listed | Cleanup standing |
|---|---|---|---|
| Nutrients | High Quality Coldwater Aquatic Life | 2016 | TMDL priority: Medium |
Reading the record
Where San Gregorio Lake sits among peers
78% of New Mexico's lakes assessed this deeply also came out mixed
New Mexico ruled definitively on 6 designated uses at San Gregorio Lake and found 1 of 6 not supported. The dataset shows 37 New Mexico lakes judged to that same depth.
New Mexico's assessed lakes are most often judged on 5 or more uses, as this one was.
Computed share from EPA ATTAINS filed records, not an official EPA rating or safety grade.
| 1 | 2 | 3 | 4 | 5+ | |
|---|---|---|---|---|---|
| All supported | 3 | 10 | 3 | 4 | 8 |
| Mixed | Not possible | 1 | 0 | 9 | 29 (this record) |
| None supported | 7 | 0 | 0 | 0 | 0 |
Ringed cell: San Gregorio Lake. Source: EPA ATTAINS, Reporting cycles 1987–2026.
Scale and rank
San Gregorio Lake is one of 176 lake-type waterbodies reported to EPA from New Mexico, and one of 58 whose reported record carries enough populated assessment or gauge data for this site to list and index it. At 36 assessed acres it ranks 20,647th by assessed size among the 38,628 lakes the dataset carries an area for, counting a state’s repeated filings of one water once, behind 20,646 lakes with a larger one.
Not yet on record
The state has not yet filed a definitive fish-consumption verdict for this record; that field populates when it reports it in a future Integrated Report cycle.
In context
Where San Gregorio Lake sits nationally
Assessed size among U.S. lakes
Distribution of assessed acreage across ATTAINS lakes filed with an area, counting a state’s repeated filings of one water once
36 Top 53% larger than 47% of 38,628 lakes
lakes the dataset carries an area for, counting a state’s repeated filings of one water once, bucketed by value
Source EPA ATTAINS · Reporting cycles 1987–2026
Listed causes vs waterbodies carrying a verdict
How many impairment causes U.S. waterbodies with a reported verdict carry
1 Longer than most more listed causes than 49% of 23,610 waterbodies carrying a verdict
named waterbodies carrying a verdict, bucketed by value
Source EPA ATTAINS · Reporting cycles 1987–2026
In both charts each bar is a band and taller bars hold more waterbodies; the dashed line and filled bar mark San Gregorio Lake. Hover or tap any bar for its full count and share.
In context
New Mexico context
ATTAINS carries 176 lake-type waterbodies in New Mexico, 46 assessed as not supporting at least one use and 28 fully supporting. Among the 58 indexed units there, San Gregorio Lake ranks 37th by listed-cause count (one listed cause) and 38th by assessed size among the 58 with an area filed; it sits in the not-supporting set (46 statewide) . Its listed causes include Nutrients, which also appears among New Mexico's most-filed impairment causes (led by Nutrients).
| Other large assessed lakes in New Mexico | Assessed acres |
|---|---|
| Navajo Reservoir Not Supporting | 12,680 |
| Elephant Butte Reservoir Not Supporting | 10,909 |
| South Lordsburg Playa Not Assessed | 7,412 |
| Ute Reservoir Not Supporting | 5,988 |
| Heron Reservoir Not Supporting | 4,497 |
| Laguna del Pero Fully Supporting | 4,477 |
Peers near San Gregorio Lake's size or cause load
Similar assessed acres
Nearest filed extents (36 acres here).
- Louise Mill Pond · 36 acres · MN
- Spring · 36 acres · MN
- <Null> · 36 acres · OR
- Penny · 36 acres · MN
Similar cause load
Nearest listed-cause counts (1 here). Peers already in the acreage column are omitted.
- Aaron · 1 causes · MN
- Aaron River Reservoir · 1 causes · MA
- Abbotts Creek (including Lexington-Thomasville Water Supply Reservoir at normal reservoir elevation, Tom-A-Lex Lake) · 1 causes · NC
- Abeniki Lake · 1 causes · NH
What to do with this record
- Assessment verdicts are cycle-based, not real-time. For fish-consumption decisions, your state advisory program is the binding source. Consumption status guide
- Impairment listings follow the Clean Water Act 303(d) process; a listing is a regulatory finding, not a closure notice. 303(d) explained
PlainLakes renders state assessment decisions and federal gauge observations without modification. It does not issue advisories.
Assessment decisions on this page are rendered directly from state Integrated Report records in EPA's ATTAINS system; gauge figures are daily-value observations from the USGS National Water Information System, no number is typed in by an editor. Overall status, use verdicts, and causes are the state's reported decisions for assessment unit NM-2106.B_10. Counts and percentiles are computed across all lake-type records PlainLakes ingests from ATTAINS. See our editorial standards & corrections policy, the methodology behind these numbers, or report a data error. Data current as of 2026-08-17. Primary sources: EPA ATTAINS and USGS National Water Information System.