Who Owns the High-Hazard Dams Without a Plan
The national emergency-action-plan gap is not spread evenly across dam owners. It is concentrated almost entirely in one category, and the pattern is orderly enough to be worth stating plainly: the less institutional the owner, the less likely the plan exists.
Among America's 17,049 high-hazard dams — those whose failure would likely cause loss of life — a privately owned dam is about 7 times more likely to have no emergency action plan on record than a federally owned one.
66% of the entire national gap sits with private owners.
Compliance by owner type
| Owner type | High-hazard dams | No EAP | Rate |
|---|---|---|---|
| Federal | 1,336 | 49 | 3.7% |
| Public Utility | 902 | 40 | 4.4% |
| State | 1,539 | 85 | 5.5% |
| Local Government | 5,239 | 550 | 10.5% |
| Private | 6,441 | 1,629 | 25.3% |
The gradient is monotonic, and it is not subtle. Federal, utility and state owners sit between 3.7% and 5.5%. Local government roughly doubles that. Private ownership is roughly five times the state rate.
That ordering is what you would expect if the binding constraint is capacity rather than willingness. A federal agency or a utility has engineering staff, a compliance function and a budget line. A county has some of that. The owner of a recreation pond dam has none of it, and in many cases does not know the structure is regulated at all — which is a very different policy problem from an institution declining to file.
Where the structural exposure is
If private ownership predicts a missing plan, then the states most exposed are the ones whose high-hazard inventory is most privately held — regardless of how well their programme currently performs.
| State | High-hazard | Privately owned | Share |
|---|---|---|---|
| Missouri | 1,478 | 1,245 | 84.2% |
| South Carolina | 679 | 545 | 80.3% |
| Hawaii | 118 | 84 | 71.2% |
| North Carolina | 1,678 | 1,179 | 70.3% |
| Idaho | 106 | 69 | 65.1% |
| Alabama | 228 | 147 | 64.5% |
| Illinois | 252 | 141 | 56.0% |
| Indiana | 282 | 157 | 55.7% |
| Mississippi | 349 | 191 | 54.7% |
| Utah | 283 | 151 | 53.4% |
| Tennessee | 275 | 139 | 50.5% |
| Pennsylvania | 788 | 392 | 49.7% |
Why this makes Alabama's new programme worth watching
Alabama created its first dam safety programme in the 2026 session, effective 1 October 2026. The enrolled text of SB 378 excludes privately owned dams, regardless of hazard designation, unless the owner voluntarily elects to participate.
Set against the table above, that is a programme whose default coverage omits the single category where compliance is weakest everywhere else — and in Alabama that category is 64% of the state's high-hazard dams. What SB 378 actually requires →
Method and limits
Basis. High-hazard-potential dams where NID records EAP status as either Yes or No. Dams recorded "Not Required" are excluded, since a plan's absence there is not a gap. Owner categories with fewer than 50 dams are not reported as rates, and states with fewer than 50 high-hazard dams are omitted from the per-state table.
What this does not show. NID reflects what state and federal programmes report to USACE. "No EAP recorded" means no plan is in the inventory, not that none exists, and reporting practice varies between programmes — some of the gradient above may be reporting capacity rather than compliance, which points the same way. This is an association in inventory data, not a causal claim about any owner or any dam.
high-hazard-eap-by-owner.csv — compliance by owner type and private-ownership share by state. Free to reuse with attribution to USACE NID and PE-Calc.
Data source. Computed from the U.S. Army Corps of Engineers National Inventory of Dams national extract, stamped 2026-8-28. Analysis by Michael Flynn, PE. Attribution appreciated; a link back is what keeps it updated.