Dam safety hazard classification, inspection frequency, and owner obligations by US state
State-by-state comparison of dam safety programs: hazard classification systems, inspection frequencies, who must inspect, and dam owner obligations. Each record is one (state, hazard class) pair with the classification name, criteria for that class, required inspection interval, inspector qualifications, and whether inspections are mandatory or voluntary. Covers the ~91,000 non-federal dams in the US. Answers 'how often must my dam be inspected in [state]', 'what hazard classification is my dam', 'do I need a licensed engineer for inspections in [state]', and 'what are the penalties for non-compliance'. The ASDSO published a 50-state summary in 2020 as a PDF; it is now 6 years stale and not structured for search. This asset maintains the current state of each program from each state's own dam safety statute and program pages.
The data
| State | Hazard classification | Classification criteria | Inspection frequency | Mandatory | Inspector qualification | Statute |
|---|---|---|---|---|---|---|
| California | Extremely High | Expected to cause considerable loss of human life or would result in an inundation area with a population of 1,000 or more. | annually | yes | Division of Safety of Dams (DSOD) | California Water Code |
| California | High | Expected to cause loss of at least one human life. | annually | yes | Division of Safety of Dams (DSOD) | California Water Code |
| Michigan | High | Emergency Action Plans (EAPs) are required for high and significant hazard dams | every 3 years | yes | professional engineer licensed in Michigan | Part 315, Dam Safety, Natural Resources and Environmental Protection Act, 1994 PA 451 |
| Vermont | High | Probable or Certain (one or more) (extensive downstream residential, commercial, or industrial development) | 2 years | no | Dam Safety Program or an engineer hired by the Owner | 10 V.S.A. § 1105 |
| California | Low | No probable loss of human life and low economic and environmental losses. Losses are expected to be principally limited to the owner's property. | annually | yes | Division of Safety of Dams (DSOD) | California Water Code |
| Michigan | Low | Dams that are over six feet in height and impound five acres or more | every 5 years | yes | professional engineer licensed in Michigan | Part 315, Dam Safety, Natural Resources and Environmental Protection Act, 1994 PA 451 |
| Vermont | Low | None Expected loss of life; Private agricultural lands, equipment and isolated non-occupied buildings, non-major roads; No disruption of services – repairs are cosmetic or rapidly repairable damage; Minimal incremental damage | 10 years | no | Dam Safety Program or an engineer hired by the Owner | 10 V.S.A. § 1105 |
| Vermont | Minimal | Same as LOW hazard; None property losses | 10 years | no | Dam Safety Program or an engineer hired by the Owner | 10 V.S.A. § 1105 |
| California | Significant | No probable loss of human life but can cause economic loss, environmental damage, impacts to critical facilities, or other significant impacts. | annually | yes | Division of Safety of Dams (DSOD) | California Water Code |
| Michigan | Significant | Emergency Action Plans (EAPs) are required for high and significant hazard dams | every 4 years | yes | professional engineer licensed in Michigan | Part 315, Dam Safety, Natural Resources and Environmental Protection Act, 1994 PA 451 |
| Vermont | Significant | None expected loss of life; Major or extensive public and private facilities property losses; Disruption of essential or critical facilities and access; Major or extensive mitigation required or impossible to mitigate | 5 years | no | Dam Safety Program or an engineer hired by the Owner | 10 V.S.A. § 1105 |
Where this came from
Every record above links the page it was taken from and quotes the sentence that states it. These are the 3 sources this dataset was assembled from.
- water.ca.govhttps://water.ca.gov/-/media/DWR-Website/Web-Pages/Programs/All-Programs/Division-of-Safety-of-Dams/Files/Publications/Division-of-Safety-of-Dams-Definitions-for-Downstream-Hazard-and-Condition-Assessment.pdf
- michigan.govhttps://www.michigan.gov/egle/about/organization/water-resources/dam-safety/rules-regs
- dec.vermont.govhttps://dec.vermont.gov/water-investment/dam-safety/inspection-program
Machine-readable
- data.jsonThe whole dataset — every record with its source URL and source quote.
- Open Knowledge Format bundleOne JSON object per line — every record's frontmatter and quoted span exactly as it is held here, in one fetch.
- How this is made and checkedWhat "verified against source" does and does not mean.