Map of All 4,128 Iowa Dams
Iowa has 4,128 dams in the National Inventory of Dams — and 95 are classified as high hazard (2% of the state’s total), meaning failure would likely cause loss of life. 5 Iowa dams are both high-hazard and in poor or unsatisfactory condition.
Use the interactive Iowa dams map below to explore every dam in the state, color-coded by hazard level. Click any dam for its condition assessment, last inspection date, and Emergency Action Plan status. Or view the full US Dams interactive map to compare Iowa to every other state.
Hazard
Condition
Purpose
Iowa Dams by the Numbers
- 4,128 total dams in Iowa
- 95 high hazard — failure would likely cause loss of life
- 274 significant hazard
- 3,759 low hazard
- 25 in poor or unsatisfactory condition (24 poor, 1 unsatisfactory)
- 5 Iowa dams are both high-hazard AND in poor/unsatisfactory condition
Data source: US Army Corps of Engineers, National Inventory of Dams (NID).
The Tallest Dams in Iowa
The tallest dam in Iowa is Red Rock Dam at 142 feet, completed in 1969. The 10 tallest Iowa dams from the National Inventory of Dams:
| Dam | Height | Year | Primary Purpose | Condition | County |
|---|---|---|---|---|---|
| Red Rock Dam | 142 ft | 1969 | Flood Risk Reduction | Not Available | Marion |
| Coralville Dam | 132 ft | 1958 | Flood Risk Reduction | Not Available | Johnson |
| Saylorville Dam | 125 ft | 1975 | Flood Risk Reduction | Not Available | Polk |
| County Basin Dam | 104 ft | 2006 | – | Satisfactory | Guthrie |
| Rathbun Dam | 100 ft | 1969 | Flood Risk Reduction | Not Available | Appanoose |
| Brushy Creek Dam | 100 ft | 1998 | Recreation | Satisfactory | Webster |
| Gibson South – Dredge Spoil Disposal | 95 ft | 1999 | Other | Satisfactory | Guthrie |
| Big Creek Terminal Dam | 95 ft | 1972 | Flood Risk Reduction | Not Available | Polk |
| Big Creek Barrier Dam | 84 ft | 1974 | Flood Risk Reduction | Not Available | Polk |
| Des Moines County Roadgrade Dam 18-70-2 | 84 ft | 1987 | Irrigation | Not Rated | Des Moines |
High-Hazard Iowa Dams in Poor Condition
The most concerning dams are those classified as high-hazard that also carry a Poor or Unsatisfactory condition rating — 5 dams in Iowa. Notable examples:
- Smokey Hollow Subwatershed Site 4 (64 ft, Woodbury County) — Flood Risk Reduction, Poor condition
- Held Watershed Site E-3 (43 ft, Plymouth County) — Flood Risk Reduction, Poor condition
- Schoenewe Dam (41 ft, Des Moines County) — Recreation, Poor condition
- Held Watershed Site E-4 (37 ft, Plymouth County) — Flood Risk Reduction, Poor condition
- Middle Pond Dam (27 ft, Iowa County) — Irrigation, Poor condition
Filter the interactive US Dams map by hazard and condition to see all of them on one view.
Dam Safety in Iowa
Dam safety in Iowa is overseen by the state dam safety program, in coordination with federal regulators: the US Army Corps of Engineers, the Bureau of Reclamation (for federal water projects), the Tennessee Valley Authority where applicable, and the Federal Energy Regulatory Commission (FERC) for licensed hydropower dams. Emergency Action Plans are typically required for high-hazard dams under state regulations.
Frequently Asked Questions
How many dams are in Iowa?
Iowa has 4,128 dams in the National Inventory of Dams tracked by the US Army Corps of Engineers: 95 high hazard, 274 significant hazard, and 3,759 low hazard.
What is the tallest dam in Iowa?
The tallest dam in Iowa is Red Rock Dam at 142 feet, completed in 1969. It is primarily a flood risk reduction structure.
How many Iowa dams are in poor condition?
25 Iowa dams are currently rated as being in Poor or Unsatisfactory condition. Of those, 5 are also classified as high-hazard — meaning failure would likely cause loss of life.
