Nevada lake · state assessment record
Lake Tahoe
Assessment decisions reported by Nevada to EPA under Clean Water Act sections 303(d) and 305(b), last assessed in the 2022 reporting cycle.
- 122,902
- Assessed acres
- Lake
- Water type
This waterbody in one line
Lake Tahoe, a lake in Nevada, is assessed as not supporting one or more designated uses, with 3 listed impairment causes in the state's most recent Integrated Report cycle (2022). By assessed acreage it sits among the largest 1% of assessed lakes nationally (38,628 lakes with a filed area); its impairment list is among the longest nationally (3 listed causes vs 23,610 assessed lakes). Nevada rules aquatic life fully supporting, and waters of extraordinary ecological or aesthetic value not supported.
- Not Supporting
- overall status
- P100
- Assessed size nationally
- P5
- 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.
Lake Tahoe 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 Lake Tahoe nationally is assessed size: 122,902 acres, larger than 100% of the 38,628 lake-type units with an area on file.
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.
Longer than most cause lists
3 listed causes puts this unit above 90% of assessed lake-type records by list length. Treat that as a coding-and-sampling signal: states that split pollutants finely mint longer lists without proving worse water.
Lake Tahoe: Category 4A reading
Category 4A means a TMDL (or equivalent) is already approved for the impairment on Lake Tahoe. 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 Lake Tahoe is Not Supporting. That tile summarizes the assessment unit; the designated-use rows and cause list are the evidence behind it.
According to the U.S. Environmental Protection Agency's ATTAINS program, Nevada carries 69 filed lake-type waterbodies in the August 2026 extract, and this page renders the assessment record EPA assigned to Lake Tahoe 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. Monitoring behind at least one of these designated-use verdicts ran through 2022, as Nevada filed it. Nevada filed its own confidence on the 10 definitive verdicts it rated: Low. That rating is the filer's, in EPA's own field, and EPA publishes no definition of the four words it offers.
| Designated use | Group | Verdict |
|---|---|---|
| Aquatic Life | Aquatic-life or related | Fully Supporting Filer confidence: Low |
| Industrial Supply | Other | Fully Supporting Filer confidence: Low |
| Irrigation | Other | Fully Supporting Filer confidence: Low |
| Municipal or Domestic Supply | Drinking-water supply designation | Fully Supporting Filer confidence: Low |
| Propagation of Wildlife | Other | Fully Supporting Filer confidence: Low |
| Recreation Involving Contact with the Water | Recreation | Fully Supporting Filer confidence: Low |
| Recreation Not Involving Contact with the Water | Recreation | Fully Supporting Filer confidence: Low |
| Water and Organisms | Aquatic-life or related | Fully Supporting Filer confidence: Low |
| Watering of Livestock | Other | Fully Supporting Filer confidence: Low |
| Waters of Extraordinary Ecological or Aesthetic Value | Aquatic-life or related | Not Supporting Filer confidence: Low |
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 |
|---|---|---|---|
| Non-Native Fish/Shellfish/Zooplankton | Waters of Extraordinary Ecological or Aesthetic Value | 2024 | TMDL approved |
| Phosphorus | Waters of Extraordinary Ecological or Aesthetic Value | 2024 | TMDL approved |
| Vertical Extinction Coefficient | Waters of Extraordinary Ecological or Aesthetic Value | 2024 | TMDL approved |
Reading the record
Lake Tahoe: Category 4A reading
4A Category 4A: impaired, TMDL completed
Nevada 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
Lake Tahoe is one of 69 lake-type waterbodies reported to EPA from Nevada, and one of 50 whose reported record carries enough populated assessment or gauge data for this site to list and index it. At 122,902 assessed acres it ranks 24th 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 23 lakes with a larger one.
Open in the register
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
Lake Tahoe has no daily USGS water-level or reservoir-storage series on this page because a site was matched, but it reports no daily water level or reservoir storage values in the trailing 365-day window. How PlainLakes links gauges.
In context
Where Lake Tahoe 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
122,902 Top 1% larger than 99%+ 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
3 Longer than most more listed causes than 90% 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 Lake Tahoe. Hover or tap any bar for its full count and share.
In context
Nevada context
ATTAINS carries 69 lake-type waterbodies in Nevada, 36 assessed as not supporting at least one use and 17 fully supporting. Among the 50 indexed units there, Lake Tahoe ranks 9th by listed-cause count (3 listed causes) and 2nd by assessed size among the 50 with an area filed; it sits in the not-supporting set (36 statewide) . Its listed causes include Phosphorus, which also appears among Nevada's most-filed impairment causes (led by Phosphorus). It also lists Non-Native Fish/Shellfish/Zooplankton; and Vertical Extinction Coefficient, outside that top-five list.
| Other large assessed lakes in Nevada | Assessed acres |
|---|---|
| Lake Mead Fully Supporting | 147,392 |
| Walker Lake Not Supporting | 35,521 |
| Lake Mohave Not Supporting | 27,001 |
| Rye Patch Reservoir Not Supporting | 16,001 |
| Lahontan Reservoir Not Supporting | 14,178 |
| Washoe Lakes Not Supporting | 5,545 |
Peers near Lake Tahoe's size or cause load
Similar assessed acres
Nearest filed extents (122,902 acres here).
- Lake Michigan Nearshore · 125,440 acres · IL
- Red (Upper Red) · 119,279 acres · MN
- Upper Red Lake · 118,943 acres · MN
- Mille Lacs · 128,076 acres · MN
Similar cause load
Nearest listed-cause counts (3 here). Peers already in the acreage column are omitted.
- 67th St. Beach · 3 causes · IL
- Abiquiu Reservoir · 3 causes · NM
- Absecon Creek (AC Reserviors) (gage to SB) · 3 causes · NJ
- Absecon Creek (below gage) · 3 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 NV06-TB-08_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.