State-by-state assessment picture
Lake water quality by state
Every state assesses its lakes on its own multi-year cycle and reports the decisions to the U.S. Environmental Protection Agency under Clean Water Act sections 303(d) and 305(b); sovereign tribal nations file their own assessments under section 518, and a row below sums every organization reporting inside that state's borders. The ATTAINS records behind this table span reporting cycles 1987-2026 across 50 states. Reported universes differ by monitoring program, so counts describe reporting coverage as much as water quality.
- 60,590
- Reported waterbodies
- 12,831
- Not supporting a use
- 50
- States covered
- 121
- Daily level record
The national picture in one line
State agencies and tribal nations report 60,590 lake-type waterbodies to EPA ATTAINS across 50 states; Wisconsin holds the most (19,871), and nationally 12,831 waterbodies are assessed as not supporting at least one designated use.
- Wisconsin (19,871)
- largest reported total
- 13,596
- fully supporting
- 6,956
- fish use not supporting
The states and tribal nations filing them has also retired 3,246 lake-type assessment units, superseded filings that are kept on the site but not counted here.
Data updated 2026-08-17
View all 50 states as a list
- New Hampshire: 3K
- Minnesota: 2K
- Michigan: 807
- Massachusetts: 678
- Florida: 636
- New Jersey: 583
- New York: 563
- Wisconsin: 493
- Illinois: 434
- Washington: 393
- Kansas: 241
- Nebraska: 219
- South Carolina: 212
- California: 202
- Virginia: 181
- Oregon: 165
- Vermont: 154
- Oklahoma: 153
- Missouri: 151
- Indiana: 145
- South Dakota: 145
- Alabama: 143
- Iowa: 137
- Pennsylvania: 135
- Texas: 125
- Rhode Island: 119
- North Carolina: 90
- Colorado: 89
- Utah: 77
- Kentucky: 72
- Louisiana: 64
- Arkansas: 62
- Tennessee: 60
- North Dakota: 52
- Idaho: 51
- Georgia: 47
- New Mexico: 46
- Connecticut: 44
- West Virginia: 44
- Delaware: 40
- Nevada: 36
- Arizona: 34
- Maryland: 32
- Maine: 31
- Montana: 28
- Mississippi: 14
- Alaska: 7
- Ohio: 7
- Wyoming: 7
- Hawaii: 2
All states
| State | Reported | Not supporting | Fully supporting | Fish use not supporting | Daily level record | Cycles |
|---|---|---|---|---|---|---|
| Wisconsin | 19,871 | 493 | 4,225 | 148 | 9 | 2022–2026 |
| Minnesota | 13,176 | 1,798 | 1,566 | 1,241 | 1 | 1998–2024 |
| Michigan | 4,307 | 807 | 3,457 | 578 | 8 | 2018–2026 |
| New Hampshire | 2,786 | 2,783 | 0 | 2,783 | 0 | 2024 |
| New York | 2,231 | 563 | 79 | Not reported | 16 | 2016–2022 |
| Indiana | 1,588 | 145 | 96 | 69 | 6 | 1998–2026 |
| Florida | 1,475 | 636 | 367 | 217 | 6 | 2024 |
| Oregon | 1,431 | 165 | 14 | 90 | 20 | 1998–2024 |
| Massachusetts | 1,191 | 678 | 40 | 241 | 1 | 2016–2026 |
| Washington | 832 | 393 | 0 | 126 | 1 | 2010–2022 |
| Illinois | 783 | 434 | 63 | 215 | 0 | 1988–2026 |
| Vermont | 712 | 154 | 558 | 44 | 0 | 2006–2026 |
| Idaho | 630 | 51 | 198 | Not reported | 4 | 2002–2024 |
| Missouri | 623 | 151 | 118 | 49 | 5 | 2026 |
| New Jersey | 611 | 583 | 21 | 261 | 1 | 2022 |
| South Carolina | 611 | 212 | 328 | 22 | 0 | 2014–2024 |
| California | 607 | 202 | 22 | 146 | 3 | 2009–2026 |
| Nebraska | 554 | 219 | 138 | Not reported | 0 | 2016–2026 |
| Pennsylvania | 516 | 135 | 381 | 62 | 0 | 1996–2026 |
| Texas | 489 | 125 | 331 | 59 | 0 | 2012–2024 |
| Oklahoma | 456 | 153 | 45 | 95 | 5 | 1987–2025 |
| West Virginia | 434 | 44 | 31 | 20 | 0 | 1996–2024 |
| Iowa | 371 | 137 | 66 | Not reported | 0 | 2024 |
| Colorado | 344 | 89 | 74 | Not reported | 8 | 1996–2024 |
| North Dakota | 340 | 52 | 143 | 4 | 4 | 2008–2022 |
| Maine | 339 | 31 | 272 | 6 | 0 | 2002–2024 |
| Kansas | 328 | 241 | 77 | 1 | 1 | 2024 |
| Alabama | 304 | 143 | 130 | 131 | 0 | 2006–2024 |
| North Carolina | 299 | 90 | 62 | 28 | 0 | 2014–2022 |
| Virginia | 275 | 181 | 50 | 126 | 0 | 2000–2026 |
| Rhode Island | 233 | 119 | 21 | 48 | 0 | 2009–2024 |
| South Dakota | 195 | 145 | 41 | Not reported | 1 | 2012–2026 |
| Connecticut | 182 | 44 | 95 | 12 | 0 | 2006–2024 |
| New Mexico | 176 | 46 | 28 | Not reported | 6 | 1998–2026 |
| Arkansas | 144 | 62 | 55 | 42 | 0 | 1992–2024 |
| Utah | 143 | 77 | 60 | Not reported | 1 | 2014–2026 |
| Kentucky | 141 | 72 | 57 | 23 | 3 | 1992–2024 |
| Georgia | 125 | 47 | 72 | Not reported | 0 | 1996–2026 |
| Tennessee | 117 | 60 | 16 | Not reported | 0 | 2017–2026 |
| Mississippi | 114 | 14 | 84 | 8 | 0 | 2014–2024 |
| Arizona | 78 | 34 | 20 | 23 | 2 | 2006–2026 |
| Alaska | 77 | 7 | 9 | Not reported | 0 | 1989–2024 |
| Louisiana | 76 | 64 | 11 | Not reported | 2 | 2016–2026 |
| Montana | 73 | 28 | 28 | Not reported | 3 | 1990–2024 |
| Nevada | 69 | 36 | 17 | 15 | 2 | 2022 |
| Maryland | 63 | 32 | 18 | 11 | 1 | 1996–2024 |
| Delaware | 47 | 40 | 6 | 5 | 0 | 2012–2026 |
| Wyoming | 14 | 7 | 6 | 0 | 0 | 1998–2024 |
| Ohio | 7 | 7 | 0 | 7 | 0 | 2026 |
| Hawaii | 2 | 2 | 0 | Not reported | 1 | 2011 |
Counts include unnamed assessment units, which are aggregated here but never receive their own page. Raw counts are not a state-vs-state water-quality score; see the rankings for share-based comparisons with minimum-sample floors.
State figures are computed from the assessment decisions state agencies and 16 sovereign tribal nations reported to EPA ATTAINS (228 of the records are tribally filed), summed by the geography a waterbody sits in; gauge counts come from the USGS National Water Information System, no number is typed in by an editor. 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.