Datasets:

referencesource
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state-dam-safety-classification

classification_criteria string	derived_fields list	hazard_class string	id string	inspection_frequency string	inspection_mandatory string	inspector_qualification string	source string	source_quote string	state string	statute_citation string	url string	verified_fields list
probable loss of life	[ "inspection_mandatory" ]	Class I	class-i-ohio	periodic	yes	Chief of the Division of Water Resources	https://ohiodnr.gov/rules-and-regulations/rules-and-regulations-by-division/water-resources/dam-levee-classification	Class I — probable loss of life	Ohio	1501:21-13	https://referencesource.org/state-dam-safety-classification/class-i-ohio/	[ "classification_criteria", "hazard_class", "inspection_frequency", "inspector_qualification", "state", "statute_citation" ]
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	[ "inspection_mandatory" ]	Class II	class-ii-ohio	periodic	yes	Chief of the Division of Water Resources	https://ohiodnr.gov/rules-and-regulations/rules-and-regulations-by-division/water-resources/dam-levee-classification	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	Ohio	1501:21-13	https://referencesource.org/state-dam-safety-classification/class-ii-ohio/	[ "classification_criteria", "hazard_class", "inspection_frequency", "inspector_qualification", "state", "statute_citation" ]
damage to low value non-residential structures and local roads	[ "inspection_mandatory" ]	Class III	class-iii-ohio	periodic	yes	Chief of the Division of Water Resources	https://ohiodnr.gov/rules-and-regulations/rules-and-regulations-by-division/water-resources/dam-levee-classification	Class III — damage to low value non-residential structures and local roads	Ohio	1501:21-13	https://referencesource.org/state-dam-safety-classification/class-iii-ohio/	[ "classification_criteria", "hazard_class", "inspection_frequency", "inspector_qualification", "state", "statute_citation" ]
losses restricted mainly to the dam	[ "inspection_mandatory" ]	Class IV	class-iv-ohio	as deemed necessary	conditional — the chief may inspect class IV dams as deemed necessary	Chief of the Division of Water Resources	https://ohiodnr.gov/rules-and-regulations/rules-and-regulations-by-division/water-resources/dam-levee-classification	Class IV — losses restricted mainly to the dam	Ohio	1501:21-13	https://referencesource.org/state-dam-safety-classification/class-iv-ohio/	[ "classification_criteria", "hazard_class", "inspection_frequency", "inspector_qualification", "state", "statute_citation" ]
Expected to cause considerable loss of human life	[ "inspection_mandatory" ]	Extremely High	extremely-high-california	annually	yes	Division of Safety of Dams	https://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	Expected to cause considerable loss of human life or would result in an Extremely High inundation area with a population of 1,000 or more.	California	California Water Code	https://referencesource.org/state-dam-safety-classification/extremely-high-california/	[ "classification_criteria", "hazard_class", "inspection_frequency", "inspector_qualification", "state", "statute_citation" ]
Expected to cause loss of at least one human life.	[ "inspection_mandatory" ]	High	high-california	annually	yes	Division of Safety of Dams	https://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	High Expected to cause loss of at least one human life.	California	California Water Code	https://referencesource.org/state-dam-safety-classification/high-california/	[ "classification_criteria", "hazard_class", "inspection_frequency", "inspector_qualification", "state", "statute_citation" ]
null	[ "inspection_mandatory" ]	High	high-michigan	every three years	yes	professional engineer licensed in Michigan	https://www.michigan.gov/egle/about/organization/water-resources/dam-safety/rules-regs	High hazard dams require an inspection report to be submitted every three years. Inspection reports must be prepared, signed, and sealed by a professional engineer licensed in Michigan.	Michigan	Part 315, Dam Safety	https://referencesource.org/state-dam-safety-classification/high-michigan/	[ "hazard_class", "inspection_frequency", "inspector_qualification", "state", "statute_citation" ]
Probable or Certain (one or more) (extensive downstream residential, commercial, or industrial development)	[ "inspection_mandatory" ]	High	high-vermont	2 years	no	Dam Safety Program or an engineer hired by the Owner	https://dec.vermont.gov/water-investment/dam-safety/inspection-program	High \| Probable or Certain (one or more) (extensive downstream residential, commercial, or industrial development) \| Not considered for this classification \| Not considered for this classification \| Not considered for this classification \| 2 years	Vermont	Vermont Dam Safety Rule	https://referencesource.org/state-dam-safety-classification/high-vermont/	[ "classification_criteria", "hazard_class", "inspection_frequency", "inspector_qualification", "state", "statute_citation" ]
located in areas where dam failure poses a risk for loss of life	[ "inspection_mandatory" ]	High	high-washington	every five years	yes	dam safety engineers	https://ecology.wa.gov/water-shorelines/water-supply/dams/info-for-dam-owners/inspections	Periodic inspections are conducted on existing "significant hazard" or "high hazard" dams — those located in areas where dam failure poses a risk for loss of life. The inspections are intended to identify deficiencies and to reasonably assure safe operation and confirm that maintenance is being adequately perform...	Washington	null	https://referencesource.org/state-dam-safety-classification/high-washington/	[ "classification_criteria", "hazard_class", "inspection_frequency", "inspector_qualification", "state" ]
null	[ "inspection_mandatory" ]	High	high-wisconsin	every two years	yes	professional engineer (PE) with experience in dams	https://dnr.wisconsin.gov/topic/dams/inspections.html	Chapter 31, Wis. Stats., requires owners of large dams to hire a professional engineer (PE) with experience in dams to inspect their dams periodically. The frequency of inspections completed by a professional engineer are related to the hazard rating of the dam: high hazard large dams – PE inspection every two years	Wisconsin	Chapter 31, Wis. Stats.	https://referencesource.org/state-dam-safety-classification/high-wisconsin/	[ "hazard_class", "inspection_frequency", "inspector_qualification", "state", "statute_citation" ]
No probable loss of human life and low economic and environmental losses.	[ "inspection_mandatory" ]	Low	low-california	annually	yes	Division of Safety of Dams	https://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	No probable loss of human life and low economic and environmental losses. Low Losses are expected to be principally limited to the owner’s property.	California	California Water Code	https://referencesource.org/state-dam-safety-classification/low-california/	[ "classification_criteria", "hazard_class", "inspection_frequency", "inspector_qualification", "state", "statute_citation" ]
null	[ "inspection_mandatory" ]	Low	low-michigan	every five years	yes	professional engineer licensed in Michigan	https://www.michigan.gov/egle/about/organization/water-resources/dam-safety/rules-regs	Low hazard dams require an inspection report to be submitted every five years.	Michigan	Part 315, Dam Safety	https://referencesource.org/state-dam-safety-classification/low-michigan/	[ "hazard_class", "inspection_frequency", "inspector_qualification", "state", "statute_citation" ]
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	[ "inspection_mandatory" ]	Low	low-vermont	10 years	no	Dam Safety Program or an engineer hired by the Owner	https://dec.vermont.gov/water-investment/dam-safety/inspection-program	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	Vermont	Vermont Dam Safety Rule	https://referencesource.org/state-dam-safety-classification/low-vermont/	[ "classification_criteria", "hazard_class", "inspection_frequency", "inspector_qualification", "state", "statute_citation" ]
null	[ "inspection_mandatory" ]	Low	low-wisconsin	every 10 years	yes	professional engineer (PE) with experience in dams	https://dnr.wisconsin.gov/topic/dams/inspections.html	Low hazard large dams – PE inspection every 10 years	Wisconsin	Chapter 31, Wis. Stats.	https://referencesource.org/state-dam-safety-classification/low-wisconsin/	[ "hazard_class", "inspection_frequency", "inspector_qualification", "state", "statute_citation" ]
Same as LOW hazard	[ "inspection_mandatory" ]	Minimal	minimal-vermont	null	no	Dam Safety Program or an engineer hired by the Owner	https://dec.vermont.gov/water-investment/dam-safety/inspection-program	Minimal \| Same as LOW hazard \| None	Vermont	Vermont Dam Safety Rule	https://referencesource.org/state-dam-safety-classification/minimal-vermont/	[ "classification_criteria", "hazard_class", "inspector_qualification", "state", "statute_citation" ]
No probable loss of human life but can cause economic loss	[ "inspection_mandatory" ]	Significant	significant-california	annually	yes	Division of Safety of Dams	https://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	No probable loss of human life but can cause economic loss, environmental Significant damage, impacts to critical facilities, or other significant impacts.	California	California Water Code	https://referencesource.org/state-dam-safety-classification/significant-california/	[ "classification_criteria", "hazard_class", "inspection_frequency", "inspector_qualification", "state", "statute_citation" ]
null	[ "inspection_mandatory" ]	Significant	significant-michigan	every four years	yes	professional engineer licensed in Michigan	https://www.michigan.gov/egle/about/organization/water-resources/dam-safety/rules-regs	Significant hazard dams require an inspection report to be submitted every four years.	Michigan	Part 315, Dam Safety	https://referencesource.org/state-dam-safety-classification/significant-michigan/	[ "hazard_class", "inspection_frequency", "inspector_qualification", "state", "statute_citation" ]
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	[ "inspection_mandatory" ]	Significant	significant-vermont	5 years	no	Dam Safety Program or an engineer hired by the Owner	https://dec.vermont.gov/water-investment/dam-safety/inspection-program	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	Vermont	Vermont Dam Safety Rule	https://referencesource.org/state-dam-safety-classification/significant-vermont/	[ "classification_criteria", "hazard_class", "inspection_frequency", "inspector_qualification", "state", "statute_citation" ]
located in areas where dam failure poses a risk for loss of life	[ "inspection_mandatory" ]	Significant	significant-washington	every five years	yes	dam safety engineers	https://ecology.wa.gov/water-shorelines/water-supply/dams/info-for-dam-owners/inspections	Note: "significant hazard" dams are inspected every five years based on a proviso in the 2009 budget passed by the Legislature.	Washington	null	https://referencesource.org/state-dam-safety-classification/significant-washington/	[ "classification_criteria", "hazard_class", "inspection_frequency", "inspector_qualification", "state" ]
null	[ "inspection_mandatory" ]	Significant	significant-wisconsin	every three to four years	yes	professional engineer (PE) with experience in dams	https://dnr.wisconsin.gov/topic/dams/inspections.html	Significant hazard large dams – PE inspection every three to four years	Wisconsin	Chapter 31, Wis. Stats.	https://referencesource.org/state-dam-safety-classification/significant-wisconsin/	[ "hazard_class", "inspection_frequency", "inspector_qualification", "state", "statute_citation" ]

Dam safety hazard classification, inspection frequency, and owner obligations by US state

Canonical, always-current version: https://referencesource.org/state-dam-safety-classification/ Machine-readable: https://referencesource.org/state-dam-safety-classification/data.json — this mirror is a point-in-time copy.

Last verified: 2026-08-18
Stale after: 2027-08-18 (past this date, prefer the canonical copy — it re-verifies on a cadence this snapshot does not)
Records: 20

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.

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Licence position

US state government works — public domain

Facts are not copyrightable; what this dataset takes from each source is a fact plus a short attributed quote linking back to the page that states it.

Sources

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