State water-quality picture · #39 by reported lake-type waterbodies
Tennessee lakes and reservoirs
Every figure on this page is computed from the assessment decisions Tennessee reported to the U.S. Environmental Protection Agency under Clean Water Act sections 303(d) and 305(b) (reporting cycles 2017–2026), plus daily water-level observations from the U.S. Geological Survey.
- 117
- Reported waterbodies
- 60
- Not supporting a use
- Not reported
- Fish use assessments
- 0
- Gauged lakes
Tennessee in one line
117 lake-type waterbodies in Tennessee are reported to EPA ATTAINS across reporting cycles 2017–2026: 60 assessed as not supporting at least one designated use, 16 fully supporting, and 41 without a definitive overall verdict. The most-listed impairment cause is Mercury in Fish Tissue, on 31 waterbodies.
- 117
- reported waterbodies
- 60
- not supporting a use
- 16
- fully supporting
- 79%
- of definitive verdicts impaired
An unassessed waterbody is neither confirmed clean nor confirmed impaired; states assess on multi-year cycles.
A compact Tennessee register with a concentrated not-supporting share
Tennessee's 117 lake-type units sit in the smallest third of state inventories, yet the ruled not-supporting share (79%) is in the upper third. The load is dense relative to register size.
Data updated 2026-08-17
According to the U.S. Environmental Protection Agency's ATTAINS program, Tennessee reported 117 lake-type waterbodies in Tennessee in the August 2026 extract. See our methodology for filer attribution and multi-year reporting cycles.
Overall-status split on Tennessee's compact register
Every reported lake-type unit in this smaller Tennessee filing set falls into exactly one overall-status bucket. The bar partitions 117 units; cause and gauge panels below stay separate.
Most-listed impairment causes in Tennessee
Waterbodies carrying each listed cause, most first
- Mercury in Fish Tissue
Mercury in Fish Tissue
31 waterbodies
- PCBs in Fish Tissue
PCBs in Fish Tissue
25 waterbodies
- Sedimentation/Siltation 9
Sedimentation/Siltation
9 waterbodies
- Dissolved Oxygen 8
Dissolved Oxygen
8 waterbodies
- Nutrients 8
Nutrients
8 waterbodies
What this shows Mercury in Fish Tissue is the most-listed impairment cause in Tennessee, on 31 of the lake-type waterbodies reported there.
Computed share from EPA ATTAINS filed records, not an official EPA rating or safety grade.
Tennessee: 79% of ruled verdicts are not-supporting, against a national share of 53%, 1.5× the national rate.
Reporting practice
Tennessee's definitive-verdict share, by the numbers
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.
Tennessee holds the 39th-largest reported lake-type inventory in the country, 117 assessment units, carrying a definitive verdict on 65% of it. The counts above describe the 76 units carrying a verdict, not all 117 reported.
The states reporting at the nearest rates are Illinois (63.5%) and Arizona (67.9%).
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.
Tennessee against every comparable state
Share of reported lake-type waterbodies carrying a definitive verdict
65% 25th of 47 higher than 22 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 Tennessee
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 | Kentucky Reservoir Assessment unit TN06040005020_1000 Fully Supporting | 99,500 |
| 2 | Chickamauga Reservoir Fully Supporting | 35,400 |
| 3 | Watts Bar Reservoir Not Supporting | 34,075 |
| 4 | Douglas Reservoir Fully Supporting | 30,400 |
| 5 | Old Hickory Reservoir Fully Supporting | 27,439 |
| 6 | Cherokee Reservoir Not Supporting | 25,964 |
| 7 | Norris Reservoir Not Supporting | 23,198 |
| 8 | Center Hill Reservoir Not Supporting | 23,051 |
| 9 | Dale Hollow Reservoir Not Supporting | 22,000 |
| 10 | Kentucky Reservoir Assessment unit TN06040001001_1000 Fully Supporting | 20,592 |
| 11 | Barkley Reservoir Assessment unit TN05130205015_1000 Fully Supporting | 20,459 |
| 12 | Barkley Reservoir Assessment unit TN05130205015_2000 Fully Supporting | 16,541 |
By cause count
Most-listed waterbodies in Tennessee
Waterbodies carrying the most listed impairment causes among the lake-type units reported by Tennessee.
| # | Waterbody | Listed causes |
|---|---|---|
| 1 | Arrow Lake Not Supporting | 7 |
| 2 | Center Hill Reservoir Not Supporting | 5 |
| 3 | Blue Basin of Reelfoot Lake Not Supporting | 4 |
| 3 | Boone Reservoir Not Supporting | 4 |
| 3 | Buck Basin Not Supporting | 4 |
| 3 | City Lake Portland Not Supporting | 4 |
| 3 | Upper Blue Basin Not Supporting | 4 |
| 3 | Watauga Embayment of Boone Reservoir Not Supporting | 4 |
| 3 | West Sandy Embayment Not Supporting | 4 |
| 10 | Clinch River Arm of Watts Bar Reservoir Not Supporting | 3 |
7 of the 10 rows in this table tie on the ranked value: 7 at 4 (rank 3). 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.
States near Tennessee's heavier not-supporting load
Two EPA ATTAINS peer sets outside Tennessee. The reporting-practice chart above stays on definitive-verdict share; the neighborhoods below emphasize cross-state nearest neighbors when the not-supporting count is in the upper third.
Similar reported inventory
Nearest states by lake-type units on the register (117 here).
- Mississippi · 114 units · 3 off
- Georgia · 125 units · 8 off
- Kentucky · 141 units · 24 off
- Utah · 143 units · 26 off
Comparable not-supporting counts
Nearest states by units assessed not supporting a use (60 here). Inventory peers above are omitted.
- Arkansas · 62 not supporting · 2 off
- Louisiana · 64 not supporting · 4 off
- North Dakota · 52 not supporting · 8 off
- Idaho · 51 not supporting · 9 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: 65% of the inventory reported from Tennessee carries a definitive verdict, 25th 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 Tennessee 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 Tennessee 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 Tennessee, 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.