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Virginia Dam Safety Act — Dam Break Inundation Zone Overlay (VA)

Tracked preemption from the Virginia overlay bundle.

Overview

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Effective
1982-07-01
Sunset
—
Authority
state
Scope
state:VA
Other Virginia preemptions
Virginia 2024-2025 Housing Preemption Bills (Status: None Enacted)Virginia Small Cell Wireless Facility Preemption (§§15.2-2316.3 / 15.2-2316.4)Virginia Stormwater Management Program (VSMP)Virginia Military Air Installation Influence Areas (§15.2-2294)Virginia Local Hazard Mitigation Plan Integration (44 CFR 201.6 / Va. Code §44-146.18:2)Virginia Family Day Home Preemption (§15.2-2292)Virginia RPA 100-ft Riparian Buffer (Chesapeake Bay Preservation Act)Virginia Floodplain Management — NFIP Coordination (Va. Code §10.1-600 et seq.)

Trigger predicate

When this evaluates true for a parcel, the law's preempted fields take precedence over base zoning.

OR
  • parcel.in_dam_break_inundation_zone == True
  • parcel.geometry geographic match

Preempted fields

2 fields on the base district schema are rewritten when the trigger fires.

FieldOpValueNote
review_typeadddam_safety_inundation_zone_review_requiredVa. Code §15.2-2209.6 / §15.2-2243.1 require localities to determine, prior to subdivision plat approval or building permit issuance for new structures, whether the property lies within the dam break inundation zone of a state-regulated impounding structure; the dam owner and DCR must receive notice and may require the developer to share in spillway upgrade costs if the new development changes the dam's hazard classification.
base_districts[*].downstream_dam_inundation_disclosureoverridemandatory_recorded_plat_notationSubdivision plats and site plans within mapped inundation zones must carry a notation; developers may be required to fund Phase I or Phase II dam-break analyses (4VAC50-20).

Citation

Authority source
Va. Code §10.1-604 et seq. (Dam Safety Act); §15.2-2209.6 (dam break inundation zone — subdivision review); §15.2-2243.1 (dam break inundation zone — building permits); regulations 4VAC50-20 (Impounding Structure Regulations)
§ §§10.1-604 through 10.1-613.6; 4VAC50-20
https://law.lis.virginia.gov/vacode/title10.1/chapter6/article2/

Research notes

Administered by Virginia DCR (Department of Conservation and Recreation) Dam Safety Program with regulatory authority vested in the Virginia Soil and Water Conservation Board. ~2,500 regulated impounding structures statewide, classified by hazard potential (4VAC50-20-40): Class I (High Hazard — probable loss of life), Class II (Significant Hazard — possible loss of life or appreciable property damage), Class III (Low Hazard — no loss of life expected), Class IV (low-volume roadway classification per 4VAC50-20-45). Inundation zone mapping is required for High and Significant hazard dams. Dam owners must hold an Operation and Maintenance Certificate; new development that increases downstream hazard classification triggers spillway upgrade obligations the developer may be required to fund (Va. Code §15.2-2243.1).