Iowa’s largest lakes range from giant flood-control reservoirs on the state’s rivers to the glacial natural lakes of the northwest. This guide ranks the largest lakes in Iowa by surface area, separates the biggest reservoir from the biggest natural lake, and links to a full guide for each. It’s part of our Iowa Lakes Database.
- The largest lakes in Iowa, by size
- The largest reservoir vs. the largest natural lake
- Where the big lakes are
- Frequently asked questions
- What is the largest lake in Iowa?
- What is the largest natural lake in Iowa?
- What are the three biggest lakes in Iowa?
- Quick answers about Iowa lakes
- What is the biggest lake in Iowa?
- What are the Iowa Great Lakes?
- How many lakes does Iowa have?
The largest lakes in Iowa, by size
- Lake Red Rock – about 15,000 acres at conservation pool (far larger at flood stage); the largest lake in Iowa, a Des Moines River reservoir near Pella.
- Rathbun Lake – about 11,000 acres, “Iowa’s Ocean,” in the south.
- Big Spirit Lake – about 5,684 acres; the largest natural lake in Iowa.
- Saylorville Lake – about 5,400 acres, near Des Moines.
- Coralville Lake – about 5,000 acres, near Iowa City.
- West Okoboji Lake – about 3,847 acres, the deep, clear jewel of the Iowa Great Lakes.
- Clear Lake – about 3,684 acres in north-central Iowa.
- Storm Lake and East Okoboji round out the big-water list.
The largest reservoir vs. the largest natural lake
It’s worth separating the two. Lake Red Rock is the largest lake in Iowa, but it’s a man-made flood-control reservoir on the Des Moines River. The largest natural lake is Big Spirit Lake in the Iowa Great Lakes – a glacial lake renowned for walleye. Iowa’s deepest lakes, by contrast, are smaller: see West Okoboji (over 130 ft) and Brushy Creek (77 ft).
Where the big lakes are
Iowa’s biggest reservoirs – Red Rock, Rathbun, Saylorville, Coralville – were built by the Corps of Engineers for flood control on the Des Moines, Chariton and Iowa rivers, mostly in the central and southern parts of the state. The biggest natural lakes – Big Spirit, West and East Okoboji, Clear Lake, Storm Lake, Lost Island – are glacial lakes in the north and northwest, with the Iowa Great Lakes being the densest cluster.
Frequently asked questions
What is the largest lake in Iowa?
Lake Red Rock, at about 15,000 acres at conservation pool (much larger at flood stage) – a Des Moines River reservoir near Pella. It’s man-made.
What is the largest natural lake in Iowa?
Big Spirit Lake, at about 5,684 acres in the Iowa Great Lakes – a glacial lake renowned for walleye.
What are the three biggest lakes in Iowa?
Lake Red Rock, Rathbun Lake and Big Spirit Lake (the largest natural lake).
Browse the full database by Largest Lakes and Small Lakes, see our best lakes roundup, or head back to the Iowa Lakes Database.
Quick answers about Iowa lakes
What is the biggest lake in Iowa?
Iowa’s largest lake is Lake Red Rock, a flood-control reservoir on the Des Moines River that covers roughly 15,000 acres at full pool. The largest natural lake is Spirit Lake (about 5,684 acres) in the Iowa Great Lakes.
What are the Iowa Great Lakes?
The Iowa Great Lakes are a cluster of natural glacial lakes in northwest Iowa near Okoboji – chiefly Spirit Lake, West Okoboji and East Okoboji – known for clear water, boating and fishing.
How many lakes does Iowa have?
Iowa has well over 100 significant public lakes and reservoirs, plus hundreds of smaller ponds and impoundments managed by the Iowa DNR.
