Updated Jul 2026
Indiana Lake Water Quality
Water quality grades for 22 monitored lakes across 63 counties.
Indiana has 22 graded lakes in our dataset, sampled across 63 counties, drawing on monitoring by the Indiana Department of Environmental Management plus federal and volunteer measurements. Only about 5% of Indiana's lakes pull an A grade — the smaller, agricultural-watershed lakes that dominate the dataset tend to carry persistent nutrient loads. 55% of lakes fall in the D or F brackets.
The state's lakes lean eutrophic: enough nutrient input to support an active algal community, with the trade-offs in clarity and dissolved oxygen that come with it. The cleanest county on average is Clay (grade A); the most-stressed is Montgomery. The gap between the top and bottom counties is large enough that "Indiana lake water quality" hides real local variation.
Grade Distribution
How Indiana’s 22 graded lakes break down from A (excellent) to F.
Top-Graded Indiana Lakes
The highest water-quality grades in Indiana — clarity, depth, and A-F grade at a glance.
Middle Lagoon Lake
Lake County, Indiana
See grade for Middle Lagoon Lake →Lake George
Steuben County, Indiana
See grade for Lake George →Dewart Lake
Kosciusko County, Indiana
See grade for Dewart Lake →Oswego Lake
Kosciusko County, Indiana
See grade for Oswego Lake →Grand Calumet Lagoon Lake
Lake County, Indiana
See grade for Grand Calumet Lagoon Lake →Big Chapman Lake
Kosciusko County, Indiana
See grade for Big Chapman Lake →Tippecanoe Lake
Kosciusko County, Indiana
See grade for Tippecanoe Lake →Lamb Lake
Johnson County, Indiana
See grade for Lamb Lake →Center Lake
Kosciusko County, Indiana
See grade for Center Lake →Lake Map
Explore Indiana Lakes
Indiana reports, fishing & travel
Indiana's cleanest and most-polluted lakes, ranked A–F
Fish species and top-graded lakes across Indiana
Species activity outlook by water temperature and season
Best-graded lakes within 50 miles of Indianapolis
Best-graded lakes within 50 miles of Fort Wayne
Reservoirs in Indiana
View all 5 reservoirs →5 of 22 Indiana lakes (23%) are man-made reservoirs in the USACE National Inventory of Dams. 5 carry a High or Significant hazard rating. The oldest matched dam dates to 1835.
EPA-Impaired Lakes in Indiana
View all 15 impaired lakes →15 of 22 Indiana lakes (68%) are officially listed as impaired under Clean Water Act §303(d) in the most recent EPA ATTAINS reporting cycle.
Indiana Fishing & Recreation
Licenses, regulations, records, and where to fish across Indiana.
Counties
All 63 Indiana counties, ranked by average lake water quality. Compare them against every county nationwide in the county rankings, browse the full directory of graded lakes, or pick a different state.
Indiana Lake Water Quality Dataset (2026)
Every graded Indiana lake in one spreadsheet — A–F grade, water clarity, phosphorus, chlorophyll-a, trophic state, size, public access, and a link to each lake's report card.
Top 25 Cleanest Lakes
| Rank | Lake | County | Grade | Clarity |
|---|---|---|---|---|
| 1 | Middle Lagoon Lake | Lake | A | - |
| 2 | Lake George | Steuben | B | 14.5 ft |
| 3 | Dewart Lake | Kosciusko | B | 10.2 ft |
| 4 | Oswego Lake | Kosciusko | B | 9.9 ft |
| 5 | Grand Calumet Lagoon Lake | Lake | B | - |
| 6 | Big Chapman Lake | Kosciusko | C | 6.9 ft |
| 7 | Tippecanoe Lake | Kosciusko | C | 8.5 ft |
| 8 | Lamb Lake | Johnson | C | 7.2 ft |
| 9 | Center Lake | Kosciusko | C | 8.7 ft |
| 10 | Syracuse Lake | Kosciusko | C | 8.8 ft |
| 11 | Lost Lake | Marshall | D | 4.9 ft |
| 12 | Koontz Lake | Starke | D | 4.9 ft |
| 13 | Lake Wawasee | Kosciusko | D | 5.9 ft |
| 14 | Webster Lake | Kosciusko | D | 5.6 ft |
| 15 | James Lake | Kosciusko | D | 5.3 ft |
| 16 | Monroe Lake | Monroe | D | 5.7 ft |
| 17 | Winona Lake | Kosciusko | F | 2.8 ft |
| 18 | Yellow Creek Lake | Kosciusko | F | 2.8 ft |
| 19 | Pike Lake | Kosciusko | F | 1.9 ft |
| 20 | Beaver Dam Lake | Kosciusko | F | 3.1 ft |
| 21 | Big Barbee Lake | Kosciusko | F | 3.1 ft |
| 22 | Lake Lemon | Monroe | F | 2.1 ft |
25 Lakes Needing Attention
| Rank | Lake | County | Grade | Clarity |
|---|---|---|---|---|
| 1 | Lake Lemon | Monroe | F | 2.1 ft |
| 2 | Big Barbee Lake | Kosciusko | F | 3.1 ft |
| 3 | Beaver Dam Lake | Kosciusko | F | 3.1 ft |
| 4 | Pike Lake | Kosciusko | F | 1.9 ft |
| 5 | Yellow Creek Lake | Kosciusko | F | 2.8 ft |
| 6 | Winona Lake | Kosciusko | F | 2.8 ft |
| 7 | Monroe Lake | Monroe | D | 5.7 ft |
| 8 | James Lake | Kosciusko | D | 5.3 ft |
| 9 | Webster Lake | Kosciusko | D | 5.6 ft |
| 10 | Lake Wawasee | Kosciusko | D | 5.9 ft |
| 11 | Koontz Lake | Starke | D | 4.9 ft |
| 12 | Lost Lake | Marshall | D | 4.9 ft |
| 13 | Syracuse Lake | Kosciusko | C | 8.8 ft |
| 14 | Center Lake | Kosciusko | C | 8.7 ft |
| 15 | Lamb Lake | Johnson | C | 7.2 ft |
| 16 | Tippecanoe Lake | Kosciusko | C | 8.5 ft |
| 17 | Big Chapman Lake | Kosciusko | C | 6.9 ft |
| 18 | Grand Calumet Lagoon Lake | Lake | B | - |
| 19 | Oswego Lake | Kosciusko | B | 9.9 ft |
| 20 | Dewart Lake | Kosciusko | B | 10.2 ft |
| 21 | Lake George | Steuben | B | 14.5 ft |
| 22 | Middle Lagoon Lake | Lake | A | - |
Where to stay near Indiana
Top-rated places to stay near Indiana
Availability and prices from Stay22 partners (Booking.com, Vrbo, Expedia). We may earn a commission from bookings, at no extra cost to you.
Planning a trip to Indiana?
Get lake water-quality report cards plus the best cabin & lodging deals near Indiana — straight to your inbox. No spam, unsubscribe anytime.
Source: EPA National Aquatic Resource Surveys, 2026.