North Carolina reservoir · state assessment record
CATAWBA RIVER (Mountain Island Lake below elevation 648)
Assessment decisions reported by N.C. Dept. of Environmental Quality to EPA under Clean Water Act sections 303(d) and 305(b), last assessed in the 2022 reporting cycle.
- 1,937
- Assessed acres
- Reservoir
- Water type
This waterbody in one line
CATAWBA RIVER (Mountain Island Lake below elevation 648), a reservoir in North Carolina, is assessed as not supporting one or more designated uses, with one listed impairment cause in the state's most recent Integrated Report cycle (2022). By assessed acreage it sits among the largest 5% by assessed acreage nationally (38,628 lakes); its impairment list is among the longest nationally (one listed cause vs 23,610 assessed lakes). Fish consumption is assessed as not supporting.
- Not Supporting
- overall status
- P96
- Assessed size nationally
- P20
- Shorter cause list
- Not Supporting
- fish consumption
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.
CATAWBA RIVER (Mountain Island Lake below elevation 648) 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 CATAWBA RIVER (Mountain Island Lake below elevation 648) nationally is assessed size: 1,937 acres, larger than 96% of the 38,628 lake-type units with an area on file.
Every ruled-on use is not supporting
On the uses this filer ruled on, fish consumption, every determination is Not Supporting. That is a use-by-use reading of the filed record, not a single overall lake grade.
CATAWBA RIVER (Mountain Island Lake below elevation 648): Category 5, TMDL still owed
Category 5 is the Integrated Report band where a TMDL (or equivalent) is still expected for CATAWBA RIVER (Mountain Island Lake below elevation 648). Read the listed causes and any cleanup actions filed beside them before treating the overall status tile as a finished restoration story.
Overall status: not supporting
The filer's overall status for CATAWBA RIVER (Mountain Island Lake below elevation 648) is Not Supporting. That tile summarizes the assessment unit; the designated-use rows and cause list are the evidence behind it.
Typical cause-list length
1 listed cause is a middle-tercile list length among assessed lake-type units. Look to IR category and use outcomes for the distinctive reading.
According to the U.S. Environmental Protection Agency's ATTAINS program, North Carolina carries 299 filed lake-type waterbodies in the August 2026 extract, and this page renders the assessment record EPA assigned to CATAWBA RIVER (Mountain Island Lake below elevation 648) 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 |
|---|---|---|
| Fish Consumption | Fish-consumption or fishery | Not Supporting |
| Water Supply | Drinking-water supply designation | Fully Supporting |
| Aquatic Life | Aquatic-life or related | Insufficient Information |
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 |
|---|---|---|---|
| PCBs - Fish Consumption Advisory | Fish Consumption | 2012 | TMDL priority: Low |
Reading the record
Where CATAWBA RIVER (Mountain Island Lake below elevation 648) sits among peers
57% of North Carolina's lakes assessed this deeply also came out mixed
North Carolina ruled definitively on 2 designated uses at CATAWBA RIVER (Mountain Island Lake below elevation 648) and found 1 of 2 not supported. The dataset shows 49 North Carolina lakes judged to that same depth.
North Carolina's assessed lakes are most often judged on 1 use; this one was judged on 2.
Computed share from EPA ATTAINS filed records, not an official EPA rating or safety grade.
| 1 | 2 | 3 | 4 | 5+ | |
|---|---|---|---|---|---|
| All supported | 50 | 12 | 0 | 0 | 0 |
| Mixed | Not possible | 28 (this record) | 8 | 1 | 0 |
| None supported | 44 | 9 | 0 | 0 | 0 |
Ringed cell: CATAWBA RIVER (Mountain Island Lake below elevation 648). Source: EPA ATTAINS, Reporting cycles 1987–2026.
Scale and rank
CATAWBA RIVER (Mountain Island Lake below elevation 648) is one of 299 lake-type waterbodies reported to EPA from North Carolina, and one of 92 whose reported record carries enough populated assessment or gauge data for this site to list and index it. At 1,937 assessed acres it ranks 1,406th 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 1,405 lakes with a larger one.
Still unfiled
The state has not yet filed a definitive recreation verdict and a definitive aquatic-life verdict for this record; those fields populate when it reports them in a future Integrated Report cycle.
In context
Where CATAWBA RIVER (Mountain Island Lake below elevation 648) 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
1,937 Top 4% larger than 96% 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
1 Longer than most more listed causes than 49% 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 CATAWBA RIVER (Mountain Island Lake below elevation 648). Hover or tap any bar for its full count and share.
In context
North Carolina context
ATTAINS carries 299 lake-type waterbodies in North Carolina, 90 assessed as not supporting at least one use and 62 fully supporting. Among the 92 indexed units there, CATAWBA RIVER (Mountain Island Lake below elevation 648) ranks 41st by listed-cause count (one listed cause) and 14th by assessed size among the 91 with an area filed; it sits in the not-supporting set (90 statewide) . Its listed causes include PCBs - Fish Consumption Advisory, which also appears among North Carolina's most-filed impairment causes (led by Chlorophyll-a - Aquatic Life Use Support).
| Other large assessed lakes in North Carolina | Assessed acres |
|---|---|
| CATAWBA RIVER (Lake Norman below elevation 760) Not Supporting | 31,332 |
| Phelps Lake Fully Supporting | 15,938 |
| Albemarle Sound Not Supporting | 15,600 |
| Nutbush Creek Arm of John H. Kerr Reservoir (below normal pool elevation 300 feet MSL or as this elevation may be adjusted by the Corps of Engineers) Fully Supporting | 9,690 |
| Lake Waccamaw Fully Supporting | 8,840 |
| ROANOKE RIVER (Lake Gaston below normal full power pool elevation 200 MSL) Fully Supporting | 7,965 |
Peers near CATAWBA RIVER (Mountain Island Lake below elevation 648)'s size or cause load
Similar assessed acres
Nearest filed extents (1,937 acres here).
- Nesowadnehunk Stream · 1,936 acres · ME
- Tombigbee River (Demopolis Lake) · 1,935 acres · AL
- Pipestem Reservoir · 1,933 acres · ND
- Long · 1,943 acres · MN
Similar cause load
Nearest listed-cause counts (1 here). Peers already in the acreage column are omitted.
- Aaron · 1 causes · MN
- Aaron River Reservoir · 1 causes · MA
- Abeniki Lake · 1 causes · NH
- Academy Brook II Dam · 1 causes · NH
What to do with this record
- The fish-consumption use is assessed as not supporting. Before eating fish from this reservoir, check your state fish-advisory program for species-specific meal limits. 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 NC11-(114). 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.