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 | annually | yes | Division of Safety of Dams | California Water Code |
| California | High | Expected to cause loss of at least one human life. | annually | yes | Division of Safety of Dams | California Water Code |
| California | Low | No probable loss of human life and low economic and environmental losses. | annually | yes | Division of Safety of Dams | California Water Code |
| California | Significant | No probable loss of human life but can cause economic loss | annually | yes | Division of Safety of Dams | California Water Code |
| Michigan | High | every three years | yes | professional engineer licensed in Michigan | Part 315, Dam Safety | |
| Michigan | Low | every five years | yes | professional engineer licensed in Michigan | Part 315, Dam Safety | |
| Michigan | Significant | every four years | yes | professional engineer licensed in Michigan | Part 315, Dam Safety | |
| Ohio | Class I | probable loss of life | periodic | yes | Chief of the Division of Water Resources | 1501:21-13 |
| Ohio | Class II | health hazard, flood water damage to homes, businesses, industrial structures (no loss of life envisioned), damage to state and interstate highways, loss of public utilities, railroads, downstream dams, only access to residential areas | periodic | yes | Chief of the Division of Water Resources | 1501:21-13 |
| Ohio | Class III | damage to low value non-residential structures and local roads | periodic | yes | Chief of the Division of Water Resources | 1501:21-13 |
| Ohio | Class IV | losses restricted mainly to the dam | as deemed necessary | conditional — the chief may inspect class IV dams as deemed necessary | Chief of the Division of Water Resources | 1501:21-13 |
| 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 | Vermont Dam Safety Rule |
| Vermont | Low | None Expected | 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 | Vermont Dam Safety Rule |
| Vermont | Minimal | Same as LOW hazard | no | Dam Safety Program or an engineer hired by the Owner | Vermont Dam Safety Rule | |
| Vermont | Significant | None expected | Major or extensive public and private facilities | 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 | Vermont Dam Safety Rule |
| Washington | High | located in areas where dam failure poses a risk for loss of life | every five years | yes | dam safety engineers | |
| Washington | Significant | located in areas where dam failure poses a risk for loss of life | every five years | yes | dam safety engineers | |
| Wisconsin | High | every two years | yes | professional engineer (PE) with experience in dams | Chapter 31, Wis. Stats. | |
| Wisconsin | Low | every 10 years | yes | professional engineer (PE) with experience in dams | Chapter 31, Wis. Stats. | |
| Wisconsin | Significant | every three to four years | yes | professional engineer (PE) with experience in dams | Chapter 31, Wis. Stats. |
Where this came from
Every record above links the page it was taken from and quotes the sentence that states it. These are the 8 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
- water.ca.govhttps://water.ca.gov/Programs/All-Programs/Division-of-Safety-of-Dams
- michigan.govhttps://www.michigan.gov/egle/about/organization/water-resources/dam-safety/rules-regs
- ohiodnr.govhttps://ohiodnr.gov/rules-and-regulations/rules-and-regulations-by-division/water-resources/dam-levee-classification
- codes.ohio.govhttps://codes.ohio.gov/ohio-administrative-code/rule-1501:21-21-01
- dec.vermont.govhttps://dec.vermont.gov/water-investment/dam-safety/inspection-program
- ecology.wa.govhttps://ecology.wa.gov/water-shorelines/water-supply/dams/info-for-dam-owners/inspections
- dnr.wisconsin.govhttps://dnr.wisconsin.gov/topic/dams/inspections.html
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.
- data.csvThe same records as one flat table, for a spreadsheet or a dataframe. The last four columns are the source URL, the quoted sentence it was read from, the date we last checked it, and which columns are our reading rather than the page's words.
- How this is made and checkedWhat "verified against source" does and does not mean.
From your own code
Same records, same quotes, without scraping the page: refsource is on PyPI and npm. Each value comes back carrying the URL it was read from and the sentence on that page that states it — .source and .quote sit on the value itself rather than in a side channel, so the checking step is available instead of skipped.
pip install refsource
refsource lookup state-dam-safety-classification state=California
npx -y refsource lookup state-dam-safety-classification state=CaliforniaSet your AI assistant up to use this
Two files and no account. Put this in .mcp.json at the root of your project — Claude Code, Cursor, Windsurf, VS Code and Codex all read that file — and your assistant can look this dataset up instead of recalling it. The server is remote, keyless and read-only.
{
"mcpServers": {
"referencesource": {
"type": "http",
"url": "https://referencesource.org/mcp"
}
}
}Add to Cursor · or, on the command line: claude mcp add --transport http referencesource https://referencesource.org/mcp --scope project
Then one line in the project's CLAUDE.md or AGENTS.md, so the assistant knows when to reach for it:
When a question needs "Dam safety hazard classification, inspection frequency, and owner obligations by US state", call the referencesource MCP server at https://referencesource.org/mcp (tool `search_records`, dataset_slug `state-dam-safety-classification`) instead of answering from memory — every record it returns carries its source URL and a verbatim quote from that page.What each tool does, and the servers built over single registers: Connect your AI assistant.