State water-quality picture · #45 by reported lake-type waterbodies
Nevada lakes and reservoirs
Every figure on this page is computed from the assessment decisions Nevada and the Pyramid Lake Paiute Tribe of the Pyramid Lake Reservation reported to the U.S. Environmental Protection Agency under Clean Water Act sections 303(d) and 305(b) (reporting cycles 2022), plus daily water-level observations from the U.S. Geological Survey.
- 69
- Reported waterbodies
- 36
- Not supporting a use
- 15
- Fish use not supporting
- 2
- Gauged lakes
Nevada in one line
69 lake-type waterbodies in Nevada are reported to EPA ATTAINS across reporting cycles 2022: 36 assessed as not supporting at least one designated use, 17 fully supporting, and 16 without a definitive overall verdict. The most-listed impairment cause is Phosphorus, on 16 waterbodies.
- 69
- reported waterbodies
- 36
- not supporting a use
- 17
- fully supporting
- 68%
- of definitive verdicts impaired
An unassessed waterbody is neither confirmed clean nor confirmed impaired; states assess on multi-year cycles.
Nevada's smaller reported lake-type inventory
At 69 units, Nevada is in the lowest third of state lake-type registers. The charts below describe that compact filing set, not a national-scale inventory.
Data updated 2026-08-17
According to the U.S. Environmental Protection Agency's ATTAINS program, Nevada and the Pyramid Lake Paiute Tribe of the Pyramid Lake Reservation reported 69 lake-type waterbodies in Nevada in the August 2026 extract. See our methodology for filer attribution and multi-year reporting cycles.
Overall-status split on Nevada's compact register
Every reported lake-type unit in this smaller Nevada filing set falls into exactly one overall-status bucket. The bar partitions 69 units; cause and gauge panels below stay separate.
Most-listed impairment causes in Nevada
Waterbodies carrying each listed cause, most first
- Phosphorus
Phosphorus
16 waterbodies
- Mercury in Fish Tissue
Mercury in Fish Tissue
15 waterbodies
- Dissolved Oxygen
Dissolved Oxygen
13 waterbodies
- Temperature
Temperature
10 waterbodies
- Iron
Iron
7 waterbodies
What this shows Phosphorus is the most-listed impairment cause in Nevada, on 16 of the lake-type waterbodies reported there.
Computed share from EPA ATTAINS filed records, not an official EPA rating or safety grade.
Nevada: 68% of ruled verdicts are not-supporting, against a national share of 53%, 1.3× the national rate.
Reporting practice
Where Nevada stands on definitive-verdict coverage
Each reporting authority decides how much of the water it files to EPA it actually assesses in a cycle. That decision sets the denominator behind every count on this page.
Nevada holds the 45th-largest reported lake-type inventory in the country, 69 assessment units, carrying a definitive verdict on 76.8% of it. The counts above describe the 53 units carrying a verdict, not all 69 reported.
The states reporting at the nearest rates are Montana (76.7%) and Maryland (79.4%).
Assessing more of an inventory is a reporting choice, set by cycle length, monitoring budget and how finely a state splits its waters into units. It is not a measure of water quality, and it is why a raw count from one state does not sit beside a raw count from another. How assessment coverage varies.
Not every unit counted here was assessed by Nevada. 2 of them were filed by a sovereign tribal nation reporting directly to EPA under Clean Water Act section 518, which lets a tribe set and apply its own water quality standards in the same manner as a state: Pyramid Lake Paiute Tribe of the Pyramid Lake Reservation (2). Those decisions are theirs, not Nevada's.
Nevada against every comparable state
Share of reported lake-type waterbodies carrying a definitive verdict
76.8% 20th of 47 higher than 27 of 47 states
the 47 comparable states, by definitive-verdict share
Each bar is a band; taller bars hold more states. The dashed line + filled bar mark this entry. Hover or tap any bar for its full count and share, and where it sits relative to this entry.
Source EPA ATTAINS · Reporting cycles 1987–2026
Each bar counts states whose definitive-verdict share falls in that 10-point band. The 47 states shown are those reporting at least 25 lake-type units; a share off a smaller inventory is precision the data does not have.
By size
Largest assessed lakes in Nevada
By assessed acreage as reported in ATTAINS. Acreage is the assessed unit's size, which can differ from a lake's full surface area.
| # | Waterbody | Assessed acres |
|---|---|---|
| 1 | Lake Mead Fully Supporting | 147,392 |
| 2 | Lake Tahoe Not Supporting | 122,902 |
| 3 | Walker Lake Not Supporting | 35,521 |
| 4 | Lake Mohave Not Supporting | 27,001 |
| 5 | Rye Patch Reservoir Not Supporting | 16,001 |
| 6 | Lahontan Reservoir Not Supporting | 14,178 |
| 7 | Washoe Lakes Not Supporting | 5,545 |
| 8 | Wild Horse Reservoir Not Supporting | 2,263 |
| 9 | Chimney Reservoir Not Supporting | 2,177 |
| 10 | South Fork Reservoir Not Supporting | 1,611 |
| 11 | Swan Reservoir Not Assessed | 1,201 |
| 12 | Topaz Lake Not Supporting | 987 |
By cause count
Most-listed waterbodies in Nevada
Waterbodies carrying the most listed impairment causes among the lake-type units reported by Nevada and by the Pyramid Lake Paiute Tribe of the Pyramid Lake Reservation.
| # | Waterbody | Listed causes |
|---|---|---|
| 1 | Rye Patch Reservoir Not Supporting | 9 |
| 2 | Willow Creek Reservoir Not Supporting | 7 |
| 3 | Chimney Reservoir Not Supporting | 6 |
| 3 | Sparks Marina Not Supporting | 6 |
| 5 | Lahontan Reservoir Not Supporting | 5 |
| 6 | Walker Lake Not Supporting | 4 |
| 6 | Washoe Lakes Not Supporting | 4 |
| 6 | Wild Horse Reservoir Not Supporting | 4 |
| 9 | Ambrosetti Pond Not Supporting | 3 |
| 9 | Bilk Creek Reservoir Not Supporting | 3 |
7 of the 10 rows in this table tie on the ranked value: 2 at 6 (rank 3), 3 at 4 (rank 6), 2 at 3 (rank 9). Tied rows share a rank and are listed in no meaningful order; where a tie reaches the top the medal is shared, because nothing separates those rows.
Gauge network
Lakes with a daily level record in Nevada
Lakes with a linked USGS gauge and a daily water-level record. Readings are daily-batch snapshots, not real-time.
States with similar inventory scale or impairment load
Two EPA ATTAINS peer sets outside Nevada. The reporting-practice chart above stays on definitive-verdict share; these neighborhoods are cross-state nearest neighbors on register size and not-supporting counts.
States with a similar reported inventory
Nearest states by lake-type units on the register (69 here).
States with a similar not-supporting load
Nearest states by units assessed not supporting a use (36 here). Inventory peers above are omitted.
- Arizona · 34 not supporting · 2 off
- Delaware · 40 not supporting · 4 off
- Maine · 31 not supporting · 5 off
- Connecticut · 44 not supporting · 8 off
Peers are nearest-neighbor matches on EPA ATTAINS register size and not-supporting counts among states with at least 25 reported units. Impairment peers skip states already listed in the inventory column so the two link sets stay distinct.
Using this state picture
- Comparisons across states hold on shares, not counts: 76.8% of the inventory reported from Nevada carries a definitive verdict, 20th of 47 comparable states. National rankings
- Fish-consumption verdicts here are assessment decisions. Species-level meal advice comes from the state fish-advisory program. Consumption guide
- Browse every named Nevada waterbody with a populated record. Browse waterbodies
PlainLakes renders state assessment decisions and federal gauge observations without modification.
Figures on this page are computed from the assessment decisions Nevada and the Pyramid Lake Paiute Tribe of the Pyramid Lake Reservation reported to EPA's ATTAINS system and from USGS National Water Information System daily values, no number is typed in by an editor. State counts aggregate every lake-type assessment unit reported by Nevada and by the Pyramid Lake Paiute Tribe of the Pyramid Lake Reservation, including unnamed units that never receive their own page. 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.