High-Hazard Dams by ZIP Code

Data current as of June 2026 — recomputed by ZipCheckup from federal data each build.

The National Inventory of Dams lists 16,896 high-hazard-potential dams across 50 U.S. states, where a failure would probably cause loss of life. Of those, 2,646 are rated in poor or unsatisfactory condition and 2,533 lack a required emergency action plan, as of June 2026. Hazard potential measures the consequence of failure, not its likelihood.

16,896 dams across 50 states carry a high hazard-potential rating — failure would probably cause loss of life — and 2,646 are rated in poor or unsatisfactory condition, as of June 2026.

By state

We report two independent facts side by side and do not rank states. A larger count reflects the size of a state's inventory and its reporting activity, not a judgment about water safety.

state	high hazard	poor condition	no eap
AK	31	4	2
AL	228	2	178
AR	197	22	9
AZ	170	34	13
CA	875	47	53
CO	472	37	3
CT	276	17	19
DE	57	3	4
FL	104	10	54
GA	546	190	106
HI	118	88	3
IA	95	5	7
ID	105	4	2
IL	252	0	50
IN	282	91	126
KS	328	75	35
KY	276	105	9
LA	42	4	1
MA	336	47	3
MD	107	33	69
ME	78	20	0
MI	161	19	3
MN	58	1	0
MO	1,477	34	50
MS	349	140	40
MT	214	41	16
NC	1,652	236	664
ND	55	12	3
NE	160	12	1
NH	162	57	4
NJ	232	56	0
NM	225	116	102
NV	162	26	2
NY	450	103	2
OH	421	132	81
OK	445	38	29
OR	173	31	2
PA	788	145	37
RI	95	34	47
SC	674	156	172
SD	92	22	4
TN	277	3	0
TX	1,607	182	317
UT	283	13	5
VA	440	52	38
VT	69	20	0
WA	416	53	35
WI	198	7	9
WV	447	41	115
WY	102	14	9

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Open data, licensed CC BY 4.0 · DOI: 10.5281/zenodo.19427201

How we compute this

We use the USACE National Inventory of Dams, the federal register of the nation's dams, and count those classified as high hazard potential — meaning a failure or misoperation would probably cause loss of human life. As of June 2026 that is 16,896 of 92,618 inventoried dams (18.2%). Hazard potential describes the consequence of a failure, not the probability that one will happen.

Within that high-hazard group we report two safety gaps the inventory records directly: dams whose condition assessment is poor or unsatisfactory (2,646), and dams where an emergency action plan is required but not prepared (2,533). We do not report downstream population, because the public inventory does not publish it.

Figures are grouped by state and recompute on every build. The undetermined hazard class is kept separate, never folded into a lower rating, and a small number of dams on territorial or tribal land are counted in the national totals but not assigned to a state.

Source: USACE National Inventory of Dams

Every number here is recomputed from public federal data on each build by open-source code in the ZipCheckup repository; a dated CSV snapshot is published with each finding. No data does not mean safe.

Frequently asked questions

How many high-hazard dams are there in the United States?

The National Inventory of Dams lists 16,896 dams with a high hazard-potential rating as of June 2026 — 18.2% of all 92,618 inventoried dams. A high rating means a failure would probably cause loss of life; it describes the consequence of failure, not how likely failure is. according to ZipCheckup's reading of federal data as of June 2026.

What does it mean when a high-hazard dam lacks an emergency action plan?

An emergency action plan sets out how a community would be warned and evacuated if a dam failed. As of June 2026, 2,533 high-hazard dams that are required to have one had not prepared it, and 2,646 high-hazard dams were rated in poor or unsatisfactory condition. ZipCheckup reports these counts by state from the National Inventory of Dams.