Maine lake · state assessment record
Flagstaff L
Assessment decisions reported by Maine to EPA under Clean Water Act sections 303(d) and 305(b), last assessed in the 2016 reporting cycle.
- 20,300
- Assessed acres
- Lake, Freshwater
- Water type
This waterbody in one line
Flagstaff L, a lake in Maine, is assessed as not supporting one or more designated uses, with one listed impairment cause in the state's most recent Integrated Report cycle (2016). 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 (one listed cause vs 23,610 assessed lakes). Aquatic life is assessed as not supporting. Fish consumption is assessed as fully supporting.
- Not Supporting
- overall status
- P100
- Assessed size nationally
- P20
- Shorter cause list
- Not Supporting
- aquatic life
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.
Where Flagstaff L stands in the filed 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 Flagstaff L nationally is assessed size: 20,300 acres, larger than 100% of the 38,628 lake-type units with an area on file.
The uses disagree
This record splits: Not Supporting on aquatic life, Fully Supporting on fish consumption, recreation. The divergence is inside the designated-use matrix, not a single all-or-nothing label.
Flagstaff L: Category 4C reading
Category 4C marks impairment from pollution that is not a pollutant (for example habitat or flow alteration) on Flagstaff L. A classic TMDL load model often does not apply; the cause list should name the non-pollutant stressor.
Overall status: not supporting
The filer's overall status for Flagstaff L 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, Maine carries 339 filed lake-type waterbodies in the August 2026 extract, and this page renders the assessment record EPA assigned to Flagstaff L 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. Maine filed its own confidence on the 10 definitive verdicts it rated: Good. 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 |
|---|---|---|
| Agricultural Supply | Other | Fully Supporting Filer confidence: Good |
| Drinking Water Supply After Disinfection | Drinking-water supply designation | Fully Supporting Filer confidence: Good |
| Fish Consumption | Fish-consumption or fishery | Fully Supporting Filer confidence: Good |
| Fish and Other Aquatic Life | Aquatic-life or related | Not Supporting Filer confidence: Good |
| Fishing | Fish-consumption or fishery | Fully Supporting Filer confidence: Good |
| Hydroelectric Power Generation | Other | Fully Supporting Filer confidence: Good |
| Industrial Process and Cooling Water Supply | Other | Fully Supporting Filer confidence: Good |
| Navigation | Other | Fully Supporting Filer confidence: Good |
| Primary Contact Recreation | Recreation | Fully Supporting Filer confidence: Good |
| Secondary Contact Recreation | Recreation | Fully Supporting Filer confidence: Good |
The record
Listed impairment causes
Causes the state listed as impairing designated uses of this lake, with the cycle each was first listed. None is a pollutant, so none carries a TMDL cleanup plan.
| Cause | Affected uses | First listed | Cleanup standing |
|---|---|---|---|
| Habitat Alterations | Fish and Other Aquatic Life | 2002 | Not applicable (non-pollutant) |
Probable sources named by the state
Each source below is listed under the cause the state filed it against, and carries the word the state filed with it — confirmed, or suspected.
- Habitat Alterations
- Impacts From Hydrostructure Flow Regulation/Modification (suspected)
Reading the record
Flagstaff L: Category 4C reading
4C Category 4C: impaired by a non-pollutant; TMDL programme does not apply
Maine filed this assessment unit as Category 4C: the impairment is not caused by a pollutant, so the Clean Water Act 303(d) cleanup-plan (TMDL) programme, which allocates pollutant loads, does not apply here.
A 4C listing is still an impairment finding about designated uses; it is not a clean bill of health. How listing and cleanup work.
Scale and rank
Flagstaff L is one of 339 lake-type waterbodies reported to EPA from Maine, and one of 302 whose reported record carries enough populated assessment or gauge data for this site to list and index it. At 20,300 assessed acres it ranks 152nd 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 151 lakes with a larger one.
In context
Where Flagstaff L 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
20,300 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
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 Flagstaff L. Hover or tap any bar for its full count and share.
In context
Maine context
ATTAINS carries 339 lake-type waterbodies in Maine, 31 assessed as not supporting at least one use and 272 fully supporting. Among the 302 indexed units there, Flagstaff L ranks 24th by listed-cause count (one listed cause) and 9th by assessed size among the 302 with an area filed; it sits in the not-supporting set (31 statewide) . Its listed causes include Habitat Alterations, which also appears among Maine's most-filed impairment causes (led by Phosphorus, Total).
| Other large assessed lakes in Maine | Assessed acres |
|---|---|
| Moosehead Lake Fully Supporting | 79,454 |
| Sebago Lake Fully Supporting | 45,624 |
| Spednick Lake Fully Supporting | 35,904 |
| Chesuncook Lake Fully Supporting | 34,926 |
| Mooselookmeguntic Lake Fully Supporting | 32,243 |
| West Grand Lake Fully Supporting | 31,174 |
Peers near Flagstaff L's size or cause load
Similar assessed acres
Nearest filed extents (20,300 acres here).
- Tennessee River (Lake Guntersville) · 20,440 acres · AL
- Barkley Reservoir · 20,459 acres · TN
- Mark Twain Lake · 20,100 acres · MO
- Houghton Lake · 20,066 acres · MI
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
- Abbotts Creek (including Lexington-Thomasville Water Supply Reservoir at normal reservoir elevation, Tom-A-Lex Lake) · 1 causes · NC
- Abeniki Lake · 1 causes · NH
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 ME0103000203_38L. 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.