Arizona lake · state assessment record
Patagonia Lake
Assessment decisions reported by Arizona to EPA under Clean Water Act sections 303(d) and 305(b), last assessed in the 2026 reporting cycle.
- 231
- Assessed acres
- Lake, Freshwater
- Water type
- Eutrophic
- Reported trophic class
This waterbody in one line
Patagonia Lake, a lake in Arizona, is assessed as not supporting one or more designated uses, with one listed impairment cause in the state's most recent Integrated Report cycle (2026). By assessed acreage it sits in the upper quartile by assessed acreage nationally (38,628 lakes); its impairment list is among the longest nationally (one listed cause vs 23,610 assessed lakes). Fish consumption is assessed as not supporting.
- Not Supporting
- overall status
- P83
- Assessed size nationally
- P20
- Shorter cause list
- Not Supporting
- fish consumption
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.
Patagonia 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: assessed size
The number that most separates Patagonia Lake nationally is assessed size: 231 acres, larger than 83% of the 38,628 lake-type units with an area on file.
The uses disagree
This record splits: Not Supporting on fish consumption, Fully Supporting on recreation. The divergence is inside the designated-use matrix, not a single all-or-nothing label.
Patagonia Lake: Category 5, TMDL still owed
Category 5 is the Integrated Report band where a TMDL (or equivalent) is still expected for Patagonia 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 Patagonia Lake is Not Supporting. That tile summarizes the assessment unit; the designated-use rows and cause list are the evidence behind it.
Typical cause-list length
1 listed cause is a middle-tercile list length among assessed lake-type units. Look to IR category and use outcomes for the distinctive reading.
According to the U.S. Environmental Protection Agency's ATTAINS program, Arizona carries 78 filed lake-type waterbodies in the August 2026 extract, and this page renders the assessment record EPA assigned to Patagonia 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 |
|---|---|---|
| Agricultural Irrigation | Other | Fully Supporting |
| Agricultural Livestock Watering | Other | Fully Supporting |
| Fish Consumption | Fish-consumption or fishery | Not Supporting |
| Full Body Contact | Recreation | Fully Supporting |
| Aquatic and Wildlife (Coldwater Fishery) | Aquatic-life or related | Insufficient Information |
| Domestic Water Source | Drinking-water supply designation | Insufficient Information |
The record
Listed impairment causes
Causes the state listed as impairing designated uses of this lake, with the cycle each was first listed and the Clean Water Act action recorded against it.
| Cause | Affected uses | First listed | Cleanup standing |
|---|---|---|---|
| Mercury in Fish Tissue | Fish Consumption | 2022 | TMDL priority: Low |
Reading the record
Where Patagonia Lake sits among peers
5 of 13 Arizona lakes assessed this deeply also came out mixed
Arizona ruled definitively on 4 designated uses at Patagonia Lake and found 1 of 4 not supported. The dataset shows 13 Arizona lakes judged to that same depth.
Arizona's assessed lakes are most often judged on 1 use; this one was judged on 4.
| 1 | 2 | 3 | 4 | 5+ | |
|---|---|---|---|---|---|
| All supported | 7 | 6 | 3 | 3 | 1 |
| Mixed | Not possible | 1 | 4 | 5 (this record) | 5 |
| None supported | 13 | 1 | 0 | 5 | 0 |
Ringed cell: Patagonia Lake. Source: EPA ATTAINS, Reporting cycles 1987–2026.
Scale and rank
Patagonia Lake is one of 78 lake-type waterbodies reported to EPA from Arizona, and one of 44 whose reported record carries enough populated assessment or gauge data for this site to list and index it. At 231 assessed acres it ranks 6,471st 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 6,470 lakes with a larger one.
Open in the register
The state has not yet filed a definitive aquatic-life verdict for this record; that field populates when it reports it in a future Integrated Report cycle.
Reported trophic class
Eutrophic is the trophic class the filing agency reported to EPA ATTAINS for this assessment unit. It describes nutrient enrichment, not whether the water is safe, and it is not a PlainLakes inference. What the trophic scale measures.
In context
Where Patagonia 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
231 Top 17% larger than 83% 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 Patagonia Lake. Hover or tap any bar for its full count and share.
In context
Arizona context
ATTAINS carries 78 lake-type waterbodies in Arizona, 34 assessed as not supporting at least one use and 20 fully supporting. Among the 44 indexed units there, Patagonia Lake ranks 21st by listed-cause count (one listed cause) and 18th by assessed size among the 44 with an area filed; it sits in the not-supporting set (34 statewide) . Its listed causes include Mercury in Fish Tissue, which also appears among Arizona's most-filed impairment causes (led by Mercury in Fish Tissue).
| Other large assessed lakes in Arizona | Assessed acres |
|---|---|
| Lake Mohave Not Supporting | 27,044 |
| Lake Havasu Not Supporting | 19,780 |
| Roosevelt Lake Not Supporting | 18,345 |
| Lake Powell Not Supporting | 9,770 |
| Lake Pleasant Not Supporting | 8,000 |
| Topock Marsh Not Assessed | 4,870 |
Peers near Patagonia Lake's size or cause load
Similar assessed acres
Nearest filed extents (231 acres here).
- Harvey Co. East Lake · 231 acres · KS
- North Pond · 231 acres · MA
- South Drywood · 231 acres · MN
- Lake Octahatchee · 231 acres · FL
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
- The fish-consumption use is assessed as not supporting. Before eating fish from this lake, check your state fish-advisory program for species-specific meal limits. 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 AZL15050301-1050_00. 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.