California reservoir · state assessment record
Pinto Lake
Assessment decisions reported by California to EPA under Clean Water Act sections 303(d) and 305(b), last assessed in the 2022 reporting cycle.
- 105
- Assessed acres
- Lake / Reservoir / Pond
- Water type
This waterbody in one line
Pinto Lake, a reservoir in California, is assessed as not supporting one or more designated uses, with 5 listed impairment causes in the state's most recent Integrated Report cycle (2022). By assessed acreage it sits above the national median by assessed acreage (38,628 lakes); its impairment list is among the longest nationally (5 listed causes vs 23,610 assessed lakes). Aquatic life is assessed as not supporting.
- Not Supporting
- overall status
- P71
- Assessed size nationally
- P1
- Shorter cause list
- Not Supporting
- aquatic life
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.
Where Pinto Lake stands in the filed 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: cause-list length
The standout filed fact is cause-list length: 5 listed impairment causes, a longer list than 97% of assessed lake-type units (n=23,610). List length tracks how states sample and code, not a severity score.
Every filed use falls short
On the uses this filer ruled on, recreation, aquatic life, every determination is Not Supporting. That is a use-by-use reading of the filed record, not a single overall lake grade.
Pinto Lake: Category 4A reading
Category 4A means a TMDL (or equivalent) is already approved for the impairment on Pinto Lake. The remaining work is implementation and tracking, read the cleanup-standing and cause rows for what the state already committed to address.
Overall status: not supporting
The filer's overall status for Pinto Lake is Not Supporting. That tile summarizes the assessment unit; the designated-use rows and cause list are the evidence behind it.
Large assessed unit
At 104.5 acres, Pinto Lake clears the upper tercile of assessed lake-type units with an area on file (11,373 still larger). Size comparisons use the portal's deduplicated lake ranking population, not raw ATTAINS row counts.
According to the U.S. Environmental Protection Agency's ATTAINS program, California carries 607 filed lake-type waterbodies in the August 2026 extract, and this page renders the assessment record EPA assigned to Pinto 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 Supply | Other | Not Supporting |
| Municipal and Domestic Supply | Drinking-water supply designation | Not Supporting |
| Spawning, Reproduction, and/Or Early Development | Aquatic-life or related | Not Supporting |
| Warm Freshwater Habitat | Aquatic-life or related | Not Supporting |
| Water Contact Recreation | Recreation | Not Supporting |
| Wildlife Habitat | Other | Not 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 |
|---|---|---|---|
| Ammonia | Warm Freshwater Habitat Also assessed as meeting: Agricultural Supply; Municipal and Domestic Supply | 2024 | TMDL approved |
| Chlorophyll-a | Water Contact Recreation, Warm Freshwater Habitat | 2024 | TMDL approved |
| Cyanobacteria Hepatotoxic Microcystins | Municipal and Domestic Supply; Water Contact Recreation; Agricultural Supply; Wildlife Habitat | 2024 | TMDL approved |
| Dissolved Oxygen | Warm Freshwater Habitat; Spawning, Reproduction, and/Or Early Development | 2024 | TMDL approved |
| Scum/Foam | Warm Freshwater Habitat | 2024 | TMDL approved |
Probable sources named by the state
Each source below is listed under the cause the state filed it against, and carries the word the state filed with it — confirmed, or suspected.
- Ammonia
- Contaminated Groundwater (suspected) Industrial/Commercial Site Stormwater Discharge (Permitted) (suspected) Agriculture (suspected) Livestock (Grazing or Feeding Operations) (suspected) Urban Runoff/Storm Sewers (suspected) Atmospheric Deposition - Toxics (suspected) On-Site Treatment Systems (Septic Systems and Similar Decentralized Systems) (suspected) Internal Nutrient Recycling (suspected)
- Chlorophyll-a
- Contaminated Groundwater (suspected) Industrial/Commercial Site Stormwater Discharge (Permitted) (suspected) Agriculture (suspected) Livestock (Grazing or Feeding Operations) (suspected) Urban Runoff/Storm Sewers (suspected) Atmospheric Deposition - Toxics (suspected) On-Site Treatment Systems (Septic Systems and Similar Decentralized Systems) (suspected) Internal Nutrient Recycling (suspected)
- Cyanobacteria Hepatotoxic Microcystins
- Contaminated Groundwater (suspected) Agriculture (suspected) Livestock (Grazing or Feeding Operations) (suspected) Urban Runoff/Storm Sewers (suspected) Atmospheric Deposition - Toxics (suspected) On-Site Treatment Systems (Septic Systems and Similar Decentralized Systems) (suspected) Internal Nutrient Recycling (suspected)
- Dissolved Oxygen
- Contaminated Groundwater (suspected) Industrial/Commercial Site Stormwater Discharge (Permitted) (suspected) Agriculture (suspected) Livestock (Grazing or Feeding Operations) (suspected) Urban Runoff/Storm Sewers (suspected) Atmospheric Deposition - Toxics (suspected) On-Site Treatment Systems (Septic Systems and Similar Decentralized Systems) (suspected) Internal Nutrient Recycling (suspected)
- Scum/Foam
- Contaminated Groundwater (suspected) Industrial/Commercial Site Stormwater Discharge (Permitted) (suspected) Agriculture (suspected) Livestock (Grazing or Feeding Operations) (suspected) Urban Runoff/Storm Sewers (suspected) Atmospheric Deposition - Toxics (suspected) On-Site Treatment Systems (Septic Systems and Similar Decentralized Systems) (suspected) Internal Nutrient Recycling (suspected)
California also recorded the source of at least one listing here as unknown, including for Cyanobacteria Hepatotoxic Microcystins.
Reading the record
Pinto Lake: Category 4A reading
4A Category 4A: impaired, TMDL completed
California filed this assessment unit as Category 4A: impaired, with a pollutant-budget TMDL already completed under 303(d). The listing remains an impairment finding; the plan is on file rather than still awaiting write-up.
Scale and rank
Pinto Lake is one of 607 lake-type waterbodies reported to EPA from California, and one of 195 whose reported record carries enough populated assessment or gauge data for this site to list and index it. At 105 assessed acres it ranks 11,374th 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 11,373 lakes with a larger one.
Still unfiled
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.
Why no water-level record
Pinto Lake has no daily USGS water-level or reservoir-storage series on this page because NWIS lists a lake monitoring site named for the waterbody, but the site is not active, and PlainLakes ingests only the active inventory, so there is no series to attach. How PlainLakes links gauges.
In context
Where Pinto 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
105 Top 29% larger than 71% 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
5 Longer than most more listed causes than 97% 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 Pinto Lake. Hover or tap any bar for its full count and share.
In context
California context
ATTAINS carries 607 lake-type waterbodies in California, 202 assessed as not supporting at least one use and 22 fully supporting. Among the 195 indexed units there, Pinto Lake ranks 21st by listed-cause count (5 listed causes) and 128th by assessed size among the 195 with an area filed; it sits in the not-supporting set (202 statewide) . Its listed causes include Dissolved Oxygen, which also appears among California's most-filed impairment causes (led by Mercury). It also lists Ammonia; Chlorophyll-a; Cyanobacteria Hepatotoxic Microcystins; and Scum/Foam, outside that top-five list.
| Other large assessed lakes in California | Assessed acres |
|---|---|
| Salton Sea Not Supporting | 233,045 |
| Tahoe, Lake Not Supporting | 84,092 |
| Goose Lake (Modoc County) Not reported | 62,385 |
| Honey Lake Not Supporting | 55,526 |
| Klamath River HU, Tule Lake and Lower Klamath Lake National Wildlife Refuge Not Supporting | 48,791 |
| Mono Lake Not Supporting | 45,299 |
Peers near Pinto Lake's size or cause load
Similar assessed acres
Nearest filed extents (105 acres here).
- Moose · 105 acres · MN
- Hidden Lake · 105 acres · OR
- Clear · 105 acres · MN
- Erwin · 105 acres · MN
Similar cause load
Nearest listed-cause counts (5 here). Peers already in the acreage column are omitted.
- Alexandria Lake No. 3 · 5 causes · NE
- Alexauken Ck (above 74d 55m) · 5 causes · NJ
- Alexauken Ck (below 74d 55m to 11BA06) · 5 causes · NJ
- Alloway Ck (Quinton to Alloway-WdstwnRd) · 5 causes · NJ
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 CAL3051003020020124122807. 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.