Risk-assessment baseline packet. County FIPS 53045. Release 2026-10, data as of 2026-09-30.
Summary
Plan status as of 2026-09-30: Approved, expires 2028-09-12. Plan: Mason County Hazard Mitigation Plan (FEMA plan 109120), approved 2023-09-13.
Since the plan was approved on 2023-09-13: 3 new hazard declarations (2 incidents) and 4 NOAA Storm Events records; details under "What changed since your last plan".
Highest expected annual loss (FEMA National Risk Index, modeled total; see B1-a): Earthquake ($26,332,449 a year), Inland Flooding ($14,807,871) and Coastal Flooding ($1,276,639).
The packet's tables are organized by the items of FEMA's Local Mitigation Plan Review Tool, Element B (B1-a to B2-c); the summaries below follow the same order.
What changed since your last plan (approved 2023-09-13)
- New federal declarations:
- 3 new hazard declarations (2 incidents): DR-4775-WA (Severe Winter Storms, Straight-Line Winds, Flooding, Landslides, and Mudslides), EM-3629-WA (Severe Storms, Straight-Line Winds, Flooding, Landslides, and Mudslides), DR-4906-WA (Severe Storms, Straight-Line Winds, Flooding, Landslides, and Mudslides)
- Storm Events records since approval:
- 4 records (data through 2026-06-30)
- Repetitive loss now:
- FMA RL 1, SRL 4 (44 CFR 77.2); any definition: 27
- Repeat-flood change:
- this release sets the baseline count.
What the packet contains
Sections in FEMA checklist order; each heading names the review item its tables support. Full tables are in the downloads above.
Supports FEMA checklist item B1-a Hazard identification
17 of the 18 National Risk Index hazards apply here.
Highest expected annual loss (NRI, modeled): Earthquake, Inland Flooding and Coastal Flooding.
Not covered by NRI (local data needed): dam failure (incl. upstream dams); levee failure; flash flood as its own subtype; ice jams; debris flows; erosion (riverine and coastal); land subsidence and sinkholes; expansive soils.
The state hazard mitigation plan also lists hazards for this county; FEMA asks the plan to explain any hazard it leaves out.
Supports FEMA checklist item B1-b Hazard location
- Avalanche, Earthquake, Hurricane, Landslide, Tornado, Tsunami, Volcanic Activity and Wildfire vary within the county; the packet lists the highest-rated census tracts for each.
- Coastal Flooding and Inland Flooding: the FEMA Flood Insurance Rate Map (FIRM) is the required location source for flooding. See the FEMA Flood Map Service Center (https://msc.fema.gov) for this county.
- Cold Wave, Drought, Hail, Heat Wave, Ice Storm, Lightning, Strong Wind and Winter Weather: affects the whole county; national data give no location within it.
Supports FEMA checklist item B1-c Hazard extent
Storm Events records for 11 of the 20 NOAA event-type groups mapped to the 18 hazards, with the scale, observed range and worst recorded event for each; the others say which local data are needed.
Worst recorded tornado, hail and thunderstorm wind (the three event types on record since the 1950s; the packet has every group):
- Hail: 1 in hail, 1985-10-22
- Tornado: EF1 tornado, 2019-10-18, 0.68 mi within this county, 90 yd wide, $150,000 property; $0 crops (2019 dollars)
Supports FEMA checklist item B1-d Previous occurrences
Federal declarations for this area: 32 declarations covering 28 separate hazard incidents counted in this packet; each with type, dates and county Public Assistance dollars.
New since the last plan (approved 2023-09-13): DR-4906-WA, EM-3629-WA and DR-4775-WA.
4 statewide declarations listed separately.
Hazards with no Storm Events record and no federal declaration are stated as such (5 of 18).
Storm Events history: 119 records (notable ones in the PDF, all of them in the Excel file).
Supports FEMA checklist item B1-e Probability of future events
FEMA annualized frequency (modeled) for each hazard, with a descriptor from a scale defined in the packet.
- Highly likely: Coastal Flooding, Landslide and Lightning
- Likely: Heat Wave, Inland Flooding and Winter Weather
- Possible: Avalanche, Earthquake, Hail, Ice Storm, Tornado, Tsunami and Wildfire
- Unlikely: Strong Wind and Volcanic Activity
Historical frequency by intensity band (tornado, hail, wind): 9 bands from Storm Events.
Supports FEMA checklist item B1-f Hazards that vary across jurisdictions
Range of census tract risk scores within the area for 18 hazards (19 tracts; rated tracts only).
2 jurisdictions: plan clock, repeat-flood count, Public Assistance dollars and event records naming the place (starting figures from federal data).
County Public Assistance in B1-d also includes applicants filed under the county that are not matched to a jurisdiction row here (for example county offices and boards filed under their own names, such as a sheriff's office or a conservation board, and state agencies, special districts and nonprofits), so the jurisdiction rows add up to less.
Supports FEMA checklist items B2-a and B2-b Vulnerability and potential impacts
The packet's table gives county-level starting figures; the plan describes impacts for each jurisdiction and its own assets.
Storm Events damage since 2023-09-13: none reported in county-coded records (0 records); $0 reported for the zone (4 zone records). Data through 2026-06-30; nominal dollars.
Local data needed
To gather:
- Critical facilities and lifelines per hazard
- A problem statement per jurisdiction per hazard
- Changes in development in hazard-prone areas since the last approval, or a statement of none (E1-a)
- Future assets
Supports FEMA checklist item B2-a Vulnerability (county context)
Population 65,689; building value $13,634,127,879 and agriculture value $62,486,333 (total, not at risk).
National Risk Index rating Relatively Moderate; social vulnerability Relatively High; community resilience Relatively Low.
Supports FEMA checklist item B2-c Repetitive loss properties
Repetitive-loss properties, FMA definition (44 CFR 77.2): 1 repetitive loss, 4 severe repetitive loss. NFIP insurance definition: 26 and 3.
Mitigated 0; insured 11; NFIP data as of 2026-08-02. Counts by occupancy group and for each jurisdiction are in the packet.