Updated August 2026
The State of Indiana's Lakes 2026
Of 22 lakes in Indiana, 50% sit in EPA's favourable condition classes for nutrients and algae and 0% in its poorer ones. 15 lakes (68.2%) are on an official impaired-waters list.
Data Report
22
Monitored lakes sampled
B
Average readings
50%
low nutrient and algae readings
68.2%
On impaired list
Indiana nutrient and algae readings
Cleanest lakes in Indiana
Cleanest combined nutrient and algae readings, 2026.
No qualifying lakes with sufficient data.
Highest measured algae
Highest measured chlorophyll-a (algae) concentration.
No qualifying lakes with sufficient data.
Trending lakes
Improving
- 1.Winona Lake — Kosciusko County
- 2.Yellow Creek Lake — Kosciusko County
- 3.Big Chapman Lake — Kosciusko County
- 4.Syracuse Lake — Kosciusko County
Declining
- 1.Lost Lake — Marshall County
- 2.Lake George — Steuben County
- 3.Koontz Lake — Starke County
- 4.Beaver Dam Lake — Kosciusko County
- 5.Oswego Lake — Kosciusko County
- 6.Lamb Lake — Johnson County
- 7.Big Barbee Lake — Kosciusko County
- 8.Lake Lemon — Monroe County
Impaired waters in Indiana
15 lakes appear on the EPA/state 303(d) impaired-waters list (15 formally listed, 0 with a cleanup plan/TMDL).
Nutrients (phosphorus, nitrogen) · 8PCBs · 5Impaired biota (cause unknown) · 3
Explore Indiana lakes
Readings combine total phosphorus, total nitrogen, chlorophyll-a, and turbidity from the EPA Water Quality Portal and state agencies. See the full methodology, the national State of America’s Lakes report, or all Indiana lakes.
Cite this report: LakeQuality, “The State of Indiana's Lakes 2026”.