State water-quality picture · #6 by reported lake-type waterbodies
Indiana lakes and reservoirs
Every figure on this page is computed from the assessment decisions Indiana reported to the U.S. Environmental Protection Agency under Clean Water Act sections 303(d) and 305(b) (reporting cycles 1998–2026), plus daily water-level observations from the U.S. Geological Survey.
- 1,588
- Reported waterbodies
- 145
- Not supporting a use
- 69
- Fish use not supporting
- 6
- Gauged lakes
Indiana in one line
1,588 lake-type waterbodies in Indiana are reported to EPA ATTAINS across reporting cycles 1998–2026: 145 assessed as not supporting at least one designated use, 96 fully supporting, and 1,347 without a definitive overall verdict. The most-listed impairment cause is PCBs in Fish Tissue, on 60 waterbodies.
- 1,588
- reported waterbodies
- 145
- not supporting a use
- 96
- fully supporting
- 60%
- of definitive verdicts impaired
An unassessed waterbody is neither confirmed clean nor confirmed impaired; states assess on multi-year cycles.
Indiana pairs a mid-pack inventory with a denser USGS gauge link-set
6 gauge-linked lakes put Indiana in the upper third of states on that link count, against a mid-third register of 1,588 units.
Data updated 2026-08-17
According to the U.S. Environmental Protection Agency's ATTAINS program, Indiana reported 1,588 lake-type waterbodies in Indiana in the August 2026 extract. See our methodology for filer attribution and multi-year reporting cycles.
How Indiana's large inventory splits across overall status
Each of the 1,588 lake-type units reported by Indiana lands in exactly one overall-status bucket. On a register this large, the bar is an inventory partition, the cause chart and national gauge below answer different questions.
Most-listed impairment causes in Indiana
Waterbodies carrying each listed cause, most first
- PCBs in Fish Tissue
PCBs in Fish Tissue
60 waterbodies
- Phosphorus, Total
Phosphorus, Total
50 waterbodies
- Biological Integrity
Biological Integrity
29 waterbodies
- Mercury in Fish Tissue
Mercury in Fish Tissue
24 waterbodies
- Escherichia coli (E. coli) 12
Escherichia coli (E. coli)
12 waterbodies
What this shows PCBs in Fish Tissue is the most-listed impairment cause in Indiana, on 60 of the lake-type waterbodies reported there.
Computed share from EPA ATTAINS filed records, not an official EPA rating or safety grade.
Indiana: 60% of ruled verdicts are not-supporting, against a national share of 53%, 1.1× the national rate.
Reporting practice
A definitive verdict is still missing for most of Indiana's inventory
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.
Indiana holds the 6th-largest reported lake-type inventory in the country, 1,588 assessment units, carrying a definitive verdict on 15.2% of it. The counts above describe the 241 units carrying a verdict, not all 1,588 reported. Indiana has also retired 8 lake-type assessment units, superseded filings that are kept on the site but not counted here.
The states reporting at the nearest rates are West Virginia (17.1%) and Oregon (12.4%).
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.
Indiana against every comparable state
Share of reported lake-type waterbodies carrying a definitive verdict
15.2% 46th of 47 higher than 1 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 Indiana
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 Michigan (Not Indexed) (Salmonid) (Osrw) Not Supporting | 154,176 |
| 2 | Patoka Reservoir (Pws) Fully Supporting | 8,880 |
| 3 | Monroe Reservoir (Lower) (Pws) Not Supporting | 6,863 |
| 4 | Brookville Reservoir Not Supporting | 5,260 |
| 5 | Monroe Reservoir (Upper) (Pws) Not Supporting | 3,887 |
| 6 | Wawasee, Lake Not Supporting | 3,410 |
| 7 | Gibson Generating Plant Lake Not Assessed | 3,200 |
| 8 | Mississinewa Reservoir Not Supporting | 3,180 |
| 9 | Salamonie Reservoir Fully Supporting | 2,855 |
| 10 | Cecil M. Harden Reservoir Not Supporting | 2,060 |
| 11 | Maxinkuckee, Lake Fully Supporting | 1,854 |
| 12 | Morse Reservoir Not Supporting | 1,800 |
By cause count
Most-listed waterbodies in Indiana
Waterbodies carrying the most listed impairment causes among the lake-type units reported by Indiana.
| # | Waterbody | Listed causes |
|---|---|---|
| 1 | Monroe Reservoir (Upper) (Pws) Not Supporting | 4 |
| 2 | Cedarville Reservoir Not Supporting | 3 |
| 2 | Eagle Creek Reservoir (Pws) Not Supporting | 3 |
| 2 | Lake Michigan Shoreline (Pws) (Osrw) Not Supporting | 3 |
| 2 | Rivir Lake Not Supporting | 3 |
| 2 | Turtle Creek Reservoir Not Supporting | 3 |
| 2 | Wolf Lake Not Supporting | 3 |
| 8 | Clear Lake Not Supporting | 2 |
| 8 | Fish Lake (Lower) Not Supporting | 2 |
| 8 | Fish Lake (Upper) Not Supporting | 2 |
9 of the 10 rows in this table tie on the ranked value: 6 at 3 (rank 2), 3 at 2 (rank 8). 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 Indiana
Lakes with a linked USGS gauge and a daily water-level record. Readings are daily-batch snapshots, not real-time.
- Cagles Mill Lake Fully Supporting USGS gauge 03358900 Level record →
- Hamilton Lake Not Supporting USGS gauge 04177700 Level record →
- Sylvan Lake Not Supporting USGS gauge 04100180 Level record →
- Waldron Lake Not Assessed USGS gauge 04100220 Level record →
- Pike Lake Not Supporting USGS gauge 03331040 Level record →
- Heron Lake Not Assessed USGS gauge 03352695 Level record →
States with similar inventory scale or impairment load
Two EPA ATTAINS peer sets outside Indiana. 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 (1,588 here).
- Florida · 1,475 units · 113 off
- Oregon · 1,431 units · 157 off
- Massachusetts · 1,191 units · 397 off
- New York · 2,231 units · 643 off
Similar not-supporting load
Nearest states by units assessed not supporting a use (145 here). Inventory peers above are omitted.
- South Dakota · 145 not supporting · 0 off
- Alabama · 143 not supporting · 2 off
- Missouri · 151 not supporting · 6 off
- Oklahoma · 153 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: 15.2% of the inventory reported from Indiana carries a definitive verdict, 46th 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 Indiana 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 Indiana 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 Indiana, 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.