Mono County, CA: risk-assessment baseline packet, release 2026-10

Summary

Plan status as of 2026-09-30: Approved, expires 2030-07-13. Plan: Mono County (FEMA plan 111793), approved 2025-07-14.

Since the plan was approved on 2025-07-14: no new federal declaration.

NOAA Storm Events records since that date: 27 records (data through 2026-06-30).

Highest expected annual loss (FEMA National Risk Index, modeled total; see B1-a): Inland Flooding ($6,866,072 a year), Earthquake ($5,089,052) and Wildfire ($1,827,733).

Repetitive-loss flood properties now: FMA RL 0, SRL 0 (44 CFR 77.2); any definition: 1.

The tables that follow are organized by the items of FEMA's Local Mitigation Plan Review Tool, Element B (B1-a to B2-c); each heading says which item its tables support.

Terms used

EAL:: expected annual loss: FEMA's modeled average yearly loss from a hazard.
NRI:: FEMA's National Risk Index (version 1.20, December 2025).
NFIP:: National Flood Insurance Program.
RL, SRL:: repetitive loss and severe repetitive loss: flood-insured properties with repeated claims (definitions in B2-c).
FMA, HMGP:: Flood Mitigation Assistance and Hazard Mitigation Grant Program, FEMA mitigation grants.
PA:: FEMA Public Assistance: disaster aid to governments and some nonprofits.
Zone-level:: NOAA logged the event for a National Weather Service forecast zone, which may include parts of neighboring counties.
County-coded:: NOAA logged the event to this county.
FIPS:: the federal code for a place; 06051 is this area.
D0 to D4:: U.S. Drought Monitor categories, from abnormally dry (D0) to exceptional drought (D4).
F/EF, EFU:: Fujita and Enhanced Fujita tornado ratings; EFU is an unrated tornado.
kt, CONUS:: knots (1 kt is about 1.15 mph); the contiguous United States.
CFR:: Code of Federal Regulations.
A4-a, E1-a:: other items of FEMA's Local Mitigation Plan Review Tool (sources, and changes since the last plan).
Dollars:: nominal (as reported, labeled with the year), not adjusted for inflation.

Plan clock

Status:: Approved, expires 2030-07-13
Plan:: Mono County (FEMA plan 111793)
Approved:: 2025-07-14
Days to expiry:: 1,382

What changed since your last plan (approved 2025-07-14)

New federal declarations:: none
Storm Events records since approval:: 27 records (data through 2026-06-30)
Repetitive loss now:: FMA RL 0, SRL 0 (44 CFR 77.2); any definition: 1
Repeat-flood change:: this release sets the baseline count.

Sources: 1, 2, 4, 6 (numbered list at the end)

Plan status for every jurisdiction listed in this county

Source: 1

Jurisdiction	Type	Status	Plan	Approved	Expires	Days to expirynegative = days since expiry	Update underway	Notes
Mono County	County	Approved, expires 2030-07-13	Mono County (FEMA plan 111793)	2025-07-14	2030-07-13	1,382		this jurisdiction approved 2026-07-15
Mammoth Lakes town	Town	Approved, expires 2030-07-13	Mono County (FEMA plan 111793)	2025-07-14	2030-07-13	1,382		this jurisdiction approved 2026-07-14
Bridgeport Public Utility District	Special District	Plan 111793 approved 2025-07-14, pending adoption here; not yet eligible	Mono County (FEMA plan 111793), pending adoption here	2025-07-14 by FEMA; not yet adopted here	2030-07-13 once adopted		FEMA tracker shows a plan approvable pending adoption	Not yet eligible: adopt the approved plan.
Hilton Creek Community Services District	Community Services District	Plan 111793 approved 2025-07-14, pending adoption here; not yet eligible	Mono County (FEMA plan 111793), pending adoption here	2025-07-14 by FEMA; not yet adopted here	2030-07-13 once adopted		FEMA tracker shows a plan approvable pending adoption	Not yet eligible: adopt the approved plan.
June Lake Public Utilities District	Special District	Plan 111793 approved 2025-07-14, pending adoption here; not yet eligible	Mono County (FEMA plan 111793), pending adoption here	2025-07-14 by FEMA; not yet adopted here	2030-07-13 once adopted		FEMA tracker shows a plan approvable pending adoption	Not yet eligible: adopt the approved plan.
Mammoth Community Water District	Water/Sewer Authority	Plan 111793 approved 2025-07-14, pending adoption here; not yet eligible	Mono County (FEMA plan 111793), pending adoption here	2025-07-14 by FEMA; not yet adopted here	2030-07-13 once adopted		FEMA tracker shows a plan approvable pending adoption	Not yet eligible: adopt the approved plan.
Mammoth Lakes Fire Protection District	Fire/EMS District	Approved, expires 2030-07-13	Mono County (FEMA plan 111793)	2025-07-14	2030-07-13	1,382		this jurisdiction approved 2026-08-27
Mono City Fire Protection District	Fire/EMS District	Approved, expires 2030-07-13	Mono County (FEMA plan 111793)	2025-07-14	2030-07-13	1,382		this jurisdiction approved 2026-08-18
Southern Mono Healthcare District	Special District	Plan 111793 approved 2025-07-14, pending adoption here; not yet eligible	Mono County (FEMA plan 111793), pending adoption here	2025-07-14 by FEMA; not yet adopted here	2030-07-13 once adopted		FEMA tracker shows a plan approvable pending adoption	Not yet eligible: adopt the approved plan.
Wheeler Crest Community Services District	Community Services District	Plan 111793 approved 2025-07-14, pending adoption here; not yet eligible	Mono County (FEMA plan 111793), pending adoption here	2025-07-14 by FEMA; not yet adopted here	2030-07-13 once adopted		FEMA tracker shows a plan approvable pending adoption	Not yet eligible: adopt the approved plan.

State plan status and tribal plans in this state: see the state page.

Supports FEMA checklist item B1-a: hazard identification

Hazards NRI does not cover (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 18 National Risk Index hazards, ranked by expected annual loss (EAL)

Sources: 5, 6

Rank by EAL	Hazard	NRI risk rating	EAL rating	EAL buildingsmodeled dollars per year	EAL agriculturemodeled dollars per year	Cost of expected deaths and injuriesFEMA's dollar value per year, not property damage	EAL total (see note)modeled dollars per year	Storm Events records, 1996 to 2026-06-30count	Why this hazard can be left outNRI Not Applicable, no declaration and no Storm Events record since 1996	Storm Events coverage note
1	Inland Flooding	Relatively Low	Relatively Low	$6,848,478	$13,805	$3,789	$6,866,072	24
2	Earthquake	Relatively Low	Relatively Moderate	$4,402,881	n/a	$686,171	$5,089,052			Storm Events does not record earthquakes.
3	Wildfire	Relatively Moderate	Relatively Moderate	$1,765,565	$51	$62,117	$1,827,733	6
4	Avalanche	Relatively High	Relatively Moderate	$10,043	n/a	$1,324,333	$1,334,377	9
5	Drought	Relatively Moderate	Relatively Moderate	n/a	$939,836	n/a	$939,836	0		No recorded events in Storm Events since 1996 (data through 2026-06-30).
6	Winter Weather	Relatively Moderate	Relatively High	$32,833	under $1	$273,072	$305,904	359
7	Lightning	Relatively Low	Relatively Low	$13,340	n/a	$97,857	$111,197	2
8	Heat Wave	Very Low	Very Low	$41	$5,267	$90,270	$95,577	0		No recorded events in Storm Events since 1996 (data through 2026-06-30).
9	Strong Wind	Very Low	Very Low	$14,566	$50	$65,787	$80,403	273		Includes 258 High Wind and 11 Strong Wind records (NOAA non-thunderstorm wind types, outside NRI's Strong Wind definition).
10	Volcanic Activity	Relatively Low	Relatively Low	$7,604	n/a	$4,791	$12,396	0		No recorded events in Storm Events since 1996 (data through 2026-06-30).
11	Landslide	Relatively Low	Relatively Low	$1,797	n/a	$8,411	$10,208	21
12	Hail	Very Low	Very Low	$180	$326	$6,723	$7,229	10
13	Tornado	Very Low	Very Low	$4,033	$13	$1,099	$5,145	0		No recorded events in Storm Events since 1996 (data through 2026-06-30).
14	Cold Wave	Very Low	Very Low	under $1	under $1	under $1	under $1	1
	Coastal Flooding	Not Applicable	Not Applicable					0		Declared 1 time; no Storm Events record of this type.
	Hurricane	Not Applicable	Not Applicable					0	NRI rates hurricane Not Applicable for this county, and no counted federal declaration for this county names it (EM-3248-CA names it but is not counted as a local occurrence; see B1-d).	No recorded events in Storm Events since 1996 (data through 2026-06-30).
	Ice Storm	Not Applicable	Not Applicable					0		Declared 1 time; no Storm Events record of this type.

Total = buildings + agriculture + population equivalence; FEMA values each expected death (or 10 injuries) at $13.7 million (2024 dollars).

NRI risk rating combines expected annual loss with social vulnerability and community resilience; EAL rating rates expected annual loss alone. Both compare this county with all U.S. counties.

Local data needed: state and local volcanic activity records (Storm Events records this hazard only in part).

Not applicable to this county per NRI, with no federal declaration and no Storm Events record since 1996: tsunami. That is the evidence for leaving them out of the plan.

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

Affects the whole county (national data give no location within it): Cold Wave, Drought, Hail, Heat Wave, Ice Storm, Lightning, Strong Wind and Winter Weather.

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.

Hazards that vary within the county: highest-rated census tracts

Source: 5

Hazard	Highest-rated census tractsNRI risk rating, score 0 to 100
Avalanche	tract 1.01 (Relatively Moderate, 85.7); tract 1.02 (Relatively Moderate, 83.5); tract 2.01 (Relatively Moderate, 81.6)
Coastal Flooding	no tract has a National Risk Index rating for this hazard
Earthquake	tract 2.01 (Relatively High, 94.6); tract 2.02 (Relatively High, 93.1); tract 1.01 (Relatively High, 92.0)
Hurricane	no tract has a National Risk Index rating for this hazard
Landslide	tract 1.01 (Relatively Moderate, 97.6); tract 1.02 (Relatively Moderate, 95.9); tract 2.01 (Very Low, 78.1)
Tornado	tract 1.01 (Very Low, 5.0); tract 2.02 (Very Low, 3.6); tract 2.01 (Very Low, 3.2)
Volcanic Activity	tract 2.02 (Relatively Low, 97.8); tract 2.01 (Relatively Low, 97.8); tract 1.01 (Relatively Low, 97.6)
Wildfire	tract 1.02 (Very High, 99.2); tract 1.01 (Relatively High, 98.1); tract 2.01 (Relatively Moderate, 94.7)

Up to 3 census tracts per hazard, highest National Risk Index rating first, then highest score; a tract number is the Census tract number (for example 1.01 is Census Tract 1.01). FEMA's Resilience Analysis and Planning Tool maps the National Risk Index for every tract: https://www.fema.gov/emergency-managers/practitioners/resilience-analysis-and-planning-tool

Supports FEMA checklist item B1-c: hazard extent

Extent: scale, observed range and worst recorded event per hazard

Sources: 6, 7

Hazard	Scale	Recordscount and years	Observed range	Worst recorded event	Most damaging (when different)	How it applies to jurisdictions	Note
Avalanche	none (count and damage only)	9 records, 1998 to 2025 (9 zone-level)		Avalanche, 2021-01-28, $250,000 property; crops not reported (2021 dollars), 1 direct injury (reported for the zone); NWS zone CAZ073		Countywide (zone-level records).	Physical measure: in event narratives only (local data needed).
Coastal Flood, Storm Surge/Tide	none in data (flood depth: FIRM)	0					Flood depth: see the FEMA Flood Insurance Rate Map.
Cold/Wind Chill, Extreme Cold/Wind Chill	wind chill	1 record, 1997 (1 zone-level)	3 days; 1 with a recorded value	3 consecutive days, 1997-01-13 to 1997-01-15, zone-level		Countywide (zone-level records).	Wind chill: in event narratives only (local data needed).
Frost/Freeze (outside NRI's Cold Wave definition)	crop damage	0					Temperature: in event narratives only (local data needed).
Drought	U.S. Drought Monitor scale (D0 to D4)	0					Storm Events enters a drought at D2 or worse east of the Rockies and D3 or worse from the Rockies west (NWS Instruction 10-1605); NRI drought counts D3 and D4 only.
Earthquake	Modified Mercalli (local data)	0					Storm Events does not record earthquakes; the USGS earthquake catalog is the source.
Hail	hail size (inches)	10 records, 2000 to 2025	0.25 in to 1 in (median 0.75 in); 10 with a recorded value	1 in hail, 2014-07-14; same size also recorded on 2013-07-03		Event records naming jurisdictions in the plan: Mammoth Lakes town (2 records).
Excessive Heat, Heat	heat index (in event narratives)	0					Heat index: in event narratives only (local data needed).
Hurricane, Tropical Storm, Tropical Depression	Saffir-Simpson	0					Storm Events files every zone of a storm's episode under the storm's type; flooding from the storm is filed as Flood or Flash Flood records.
Ice Storm	Sperry-Piltz ice scale (local data)	0					Ice thickness: in event narratives only (local data needed).
Flash Flood, Flood, Lakeshore Flood	damage and flood days (flood depth: FIRM)	24 records, 1997 to 2024 (1 zone-level)		Flash Flood, 2015-10-18, $300,000 property; $0 crops (2015 dollars)		Event records naming jurisdictions in the plan: Mammoth Lakes town (1 record). Zone-level records (1) apply countywide.	Flood depth: see the FEMA Flood Insurance Rate Map. Storm Events damage is often $0 or blank for floods, major ones included; FEMA Public Assistance by declaration (B1-d) shows which floods cost the most.
Debris Flow	none (count and damage only)	21 records, 2011 to 2025 (1 zone-level)		Debris Flow, 2021-07-31, $41,000 property; $0 crops (2021 dollars)		No event record names a jurisdiction in the plan. Zone-level records (1) apply countywide.	Physical measure: in event narratives only (local data needed).
Lightning	annualized frequency (the measure FEMA's Local Mitigation Planning Handbook names)	2 records, 2004 to 2019		Lightning, 2019-07-25, damage not reported, 1 direct injury		Event records naming jurisdictions in the plan: Mammoth Lakes town (1 record).	Storm Events lists lightning with damage or casualties; physical measure in event narratives only (local data needed).
High Wind and Strong Wind (outside NRI's Strong Wind definition)	wind speed (kt and mph)	269 records, 1996 to 2026 (269 zone-level)	33 kt (38 mph) to 143 kt (165 mph) (median 68 kt (78 mph)); 267 with a recorded value	143 kt (165 mph) measured gust, High Wind, 2019-01-17; NWS zone CAZ073	Strong Wind, 2008-12-19, $3,000,000 property; $0 crops, reported for the zone (2008 dollars)	Countywide (zone-level records).
Thunderstorm Wind	wind speed (kt and mph)	8 records, 1980 to 2025	50 kt (58 mph) to 70 kt (81 mph) (median 54 kt (62 mph)); 5 with a recorded value	70 kt (81 mph), measurement type not recorded, Thunderstorm Wind, 1980-09-13	Thunderstorm Wind, 2002-07-12, $500 property; crops not reported (2002 dollars)	No event record names a jurisdiction in the plan.
Tornado	Enhanced Fujita (Fujita before Feb 2007)	0					Before 1996 a tornado is listed once, under the county where it began, with its whole path's rating and length; from 1996 on, each county lists its own segment. Length is not used to rank tornadoes (see Methods).
Volcanic Ash, Volcanic Ashfall	Volcanic Explosivity Index (local data)	0					Physical measure: in event narratives only (local data needed).
Wildfire	acres burned (local data)	6 records, 2007 to 2025 (6 zone-level)		Wildfire, 2007-06-05, $40,000 property; $10,000 crops (2007 dollars); NWS zone CAZ073		Countywide (zone-level records).	Acres burned: in event narratives only (local data needed).
Winter Storm, Heavy Snow, Blizzard, Lake-Effect Snow, Winter Weather, Sleet	none in data (snowfall: local data)	359 records, 1996 to 2026 (359 zone-level)		Winter Storm, 1996-12-21, $50,000 property; crops not reported (1996 dollars); NWS zone CAZ073	Blizzard, 1996-12-22, $50,000 property; crops not reported, reported for the zone (1996 dollars)	Countywide (zone-level records).	Snow depth: in event narratives only (local data needed).

Storm Events records are more complete after 1996; before 1996 only Tornado (from 1950), Hail and Thunderstorm Wind (from 1955) exist. Zone-level records whose zone no NWS zone-county file places in this county (mostly before 2020) are not counted here (the Methods page explains the zone matching).

Dollars are nominal (as reported), labeled with the year; not adjusted for inflation.

Supports FEMA checklist item B1-d: previous occurrences

Federal declarations for this county: 14 declarations covering 10 separate hazard incidents counted in this packet (declarations for the same incident count once; non-natural and evacuation-only declarations are not counted).

Federal disaster declarations for this county

Sources: 1, 2, 3

Declared	Incident began	FEMA number	Type	Title	Mapped hazard	County Public Assistancefederal share obligated, nominal dollars	Flags	Notes
2023-04-03	2023-02-21	DR-4699-CA	Major disaster	Severe Winter Storms, Straight-Line Winds, Flooding, Landslides, and Mudslides	Ice Storm; Inland Flooding; Landslide; Strong Wind; Winter Weather	$3,052,503.61	within last 5 years
2023-03-10	2023-03-09	EM-3592-CA	Emergency	Severe Winter Storms, Flooding, Landslides, and Mudslides	Inland Flooding (primary); also designated: Landslide, Winter Weather	no Public Assistance recorded	within last 5 years	same incident as DR-4699
2023-01-09	2023-01-08	EM-3591-CA	Emergency	Severe Winter Storms, Flooding, and Mudslides	Inland Flooding (primary); also designated: Landslide, Winter Weather	no Public Assistance recorded	within last 5 years
2020-03-22	2020-01-20	DR-4482-CA	Major disaster	COVID-19 Pandemic	Non-natural, not counted	$1,783,215.02
2020-03-13	2020-01-20	EM-3428-CA	Emergency	COVID-19	Non-natural, not counted	no Public Assistance recorded		same incident as DR-4482
2017-04-01	2017-02-01	DR-4308-CA	Major disaster	Severe Winter Storms, Flooding, and Mudslides	Inland Flooding (primary); also designated: Landslide, Winter Weather	$297,950.69
2017-03-16	2017-01-18	DR-4305-CA	Major disaster	Severe Winter Storms, Flooding, and Mudslides	Inland Flooding (primary); also designated: Landslide, Winter Weather	$28,826.52
2017-02-14	2017-01-03	DR-4301-CA	Major disaster	Severe Winter Storms, Flooding, and Mudslides	Inland Flooding; Landslide; Winter Weather	$64,967.67
2005-09-13	2005-08-29	EM-3248-CA	Emergency	Hurricane Katrina Evacuation	Hurricane: evacuation support, not a local hazard event; not counted	no Public Assistance recorded
1997-01-04	1996-12-28	DR-1155-CA	Major disaster	Severe Storms, Flooding, Mud and Landslides	Inland Flooding; Landslide	no Public Assistance recorded
1995-03-12	1995-02-13	DR-1046-CA	Major disaster	Severe Winter Storms, Flooding Landslides, Mud Flow	Inland Flooding; Landslide; Winter Weather	no Public Assistance recorded
1986-02-21	1986-02-12	DR-758-CA	Major disaster	Severe Storms & Flooding	Inland Flooding	no Public Assistance recorded
1978-02-15	1978-02-15	DR-547-CA	Major disaster	Coastal Storms, Mudslides & Flooding	Coastal Flooding (primary); also designated: Landslide	no Public Assistance recorded
1969-01-26	1969-01-26	DR-253-CA	Major disaster	Severe Storms & Flooding	Inland Flooding	no Public Assistance recorded

School districts and special districts in this county: $1,387,446.01 (included in the county total above). Public Assistance matched by applicant name to the school districts and special districts FEMA lists as plan participants in this county. They have no row of their own in the jurisdiction table, so their total is listed here. These dollars are already included in the county PA column of the declarations table (the FEMA record places each applicant in this county), so this line is not added to it.

County Public Assistance: applicants the FEMA record places in this county, including any state agencies FEMA files there; statewide rows are listed on the state page; federal share obligated, nominal dollars.

Statewide declarations

Source: 2

Declared	Incident began	FEMA number	Type	Title	Mapped hazard
1964-04-01	1964-04-01	DR-169-CA	Major disaster	Seismic Sea Wave	Tsunami
1963-12-21	1963-12-21	DR-161-CA	Major disaster	Flood Due to Broken Dam	Other, not an NRI hazard; not counted
1963-02-25	1963-02-25	DR-145-CA	Major disaster	Severe Storms, Heavy Rains & Flooding	Inland Flooding
1962-10-24	1962-10-24	DR-138-CA	Major disaster	Severe Storms & Flooding	Inland Flooding
1962-03-06	1962-03-06	DR-122-CA	Major disaster	Floods	Inland Flooding
1961-11-16	1961-11-16	DR-119-CA	Major disaster	Fire (Los Angeles County)	Wildfire
1958-04-04	1958-04-04	DR-82-CA	Major disaster	Heavy Rainstorms & Flood	Inland Flooding
1956-12-29	1956-12-29	DR-65-CA	Major disaster	Forest Fire	Wildfire
1955-12-23	1955-12-23	DR-47-CA	Major disaster	Flood	Inland Flooding
1954-02-05	1954-02-05	DR-15-CA	Major disaster	Flood & Erosion	Inland Flooding

FEMA recorded these with designated area Statewide and no county, so they are listed on every county page in the state and not counted with county rows. Local data needed: whether each one affected this county.

5 Fire Management declarations (1977-08-07 to 1988-09-13) FEMA filed as Statewide with no county; each names one local fire. Listed on the state page.

Previous occurrences by hazard, with explicit no-event rows

Sources: 2, 6, 7

Hazard	Storm Events records, all years on file(years in the Period column)	Since plan approvalrecords	In the 12 months before plan approvalrecords	Last 5 yearsrecords	Declared incidents, all yearsseparate disasters	Period	Statement
Avalanche	9	1	0	1	0	1996 to 2026-06-30
Coastal Flooding	0	0	0	0	1	1996 to 2026-06-30	No Storm Events records of this type; 1 federal declared incident (see declarations table)
Cold Wave	1	0	0	0	0	1996 to 2026-06-30
Drought	0	0	0	0	0	1996 to 2026-06-30	No recorded events, 1996 to 2026-06-30, NOAA NCEI Storm Events
Earthquake	0	0	0	0	0		Storm Events does not record earthquakes; the USGS earthquake catalog is the source.
Hail	10	1	0	1	0	1955 to 2026-06-30
Heat Wave	0	0	0	0	0	1996 to 2026-06-30	No recorded events, 1996 to 2026-06-30, NOAA NCEI Storm Events
Hurricane	0	0	0	0	0	1996 to 2026-06-30	No recorded events, 1996 to 2026-06-30, NOAA NCEI Storm Events
Ice Storm	0	0	0	0	1	1996 to 2026-06-30	No Storm Events records of this type; 1 federal declared incident (see declarations table)
Inland Flooding	24	0	0	6	9	1996 to 2026-06-30
Landslide	21	1	4	6	8	1996 to 2026-06-30
Lightning	2	0	0	0	0	1996 to 2026-06-30
Strong Wind	277	12	32	122	1	1955 to 2026-06-30	Includes 258 High Wind and 11 Strong Wind records.
Tornado	0	0	0	0	0	1950 to 2026-06-30	No recorded events, 1950 to 2026-06-30, NOAA NCEI Storm Events
Volcanic Activity	0	0	0	0	0	1996 to 2026-06-30	No recorded events, 1996 to 2026-06-30, NOAA NCEI Storm Events
Wildfire	6	1	0	1	0	1996 to 2026-06-30
Winter Weather	359	11	15	90	6	1996 to 2026-06-30

Notable Storm Events records

Sources: 1, 6, 7

Date	Event type	Magnitude or extent	Damagenominal dollars	Deaths, injuriesdirect only	Location	Flags	Why listed
2025-12-26	Avalanche		$0 property; $0 crops, reported for the zone (2025 dollars)	1, 0	NWS zone CAZ073 (MONO), zone-level	new since last plan; within last 5 years	deaths or injuries recorded
2021-07-31	Debris Flow		$41,000 property; $0 crops (2021 dollars)	0, 0	WALKER		B1-c worst recorded: Debris Flow
2021-01-28	Avalanche		$250,000 property; crops not reported, reported for the zone (2021 dollars)	0, 1	NWS zone CAZ073 (MONO), zone-level		B1-c worst recorded: Avalanche
2019-07-25	Lightning		damage not reported	0, 1	WALKER		B1-c worst recorded: Lightning
2019-01-17	High Wind	143 kt (165 mph) measured gust	damage not reported	0, 0	NWS zone CAZ073 (MONO), zone-level		B1-c worst recorded: High Wind and Strong Wind
2016-10-15	Strong Wind	35 kt (40 mph) estimated gust	property not reported; $0 crops, reported for the zone (2016 dollars)	3, 0	NWS zone CAZ073 (MONO), zone-level		deaths or injuries recorded
2015-10-18	Flash Flood		$300,000 property; $0 crops (2015 dollars)	0, 0	CHALFANT		B1-c worst recorded: Flash Flood, Flood, Lakeshore Flood
2014-07-14	Hail	1 in	$0 property; $0 crops (2014 dollars)	0, 0	BRIDGEPORT		B1-c worst recorded: Hail
2007-06-05	Wildfire		$40,000 property; $10,000 crops, reported for the zone (2007 dollars)	0, 0	NWS zone CAZ073 (MONO), zone-level		B1-c worst recorded: Wildfire
2006-02-01	Avalanche		damage not reported	1, 1	NWS zone CAZ073 (MONO), zone-level		deaths or injuries recorded
1996-12-21	Winter Storm		$50,000 property; crops not reported, reported for the zone (1996 dollars)	0, 0	NWS zone CAZ073 (MONO), zone-level		B1-c worst recorded: Winter Storm, Heavy Snow, Blizzard, Lake-Effect Snow, Winter Weather, Sleet
1980-09-13	Thunderstorm Wind	70 kt (81 mph), measurement type not recorded	damage not recorded (pre-1996 record)	0, 0	location not recorded		B1-c worst recorded: Thunderstorm Wind

The full list is in the Excel file, sheet "B1-d Storm Events history" (709 rows).

Location is the place NOAA recorded, as written in its data; it need not be a jurisdiction in this plan.

Local data needed: state-declared emergencies, from your state emergency management agency (federal data do not include them).

Tribal and special-area declarations in this state are listed on the state page.

Supports FEMA checklist item B1-e: probability of future events

Probability: FEMA annualized frequency and descriptor per hazard

Sources: 5, 6

Hazard	FEMA annualized frequency (modeled)unit per row	Unit	In plain terms	Descriptor	Descriptor basis	NRI events or days in its record period (hail, wind and tornado are area-weighted, so can be fractional)	NRI period	Location	Note
Avalanche	0.2	events per year	about 1 in 5 years	Likely	FEMA annualized frequency (modeled)	6	1994 to 2023 (30 years)	see B1-f
Coastal Flooding		events per year at a location (modeled)				not shown	modeled	see B1-f	Not Applicable in NRI for this county; no descriptor.
Cold Wave	0.000000445	event-days per year	about 0.000000445 days per year	Possible (from Storm Events: 1 of 30 years)	event-days in 1 of 30 years, 1996 to 2025 (3.33%)	0.00000824	2005-11-12 to 2024-11-12 (19 years)	countywide
Drought	116	event-days per year	about 116 days per year		event-days in 0 of 30 years, 1996 to 2025 (0%)	3,409	2000 to 2025 (25.25 years; D3 and D4 only)	countywide	No Storm Events drought record, 1996 to 2025
Earthquake	0.0891	annual probability at a location	chance a given location in the county has at least minor-damage shaking in a year: 8.91%			not shown	modeled	see B1-f	No descriptor (Storm Events does not record earthquakes).
Hail	0.0596	events per year	about 1 in 17 years	Possible	FEMA annualized frequency (modeled)	2.3 (modeled)	1986 to 2023 (38 years)	countywide
Heat Wave	0.529	event-days per year	about 0.529 days per year		event-days in 0 of 30 years, 1996 to 2025 (0%)	2.01	2005-11-12 to 2024-11-12 (19 years)	countywide	No Storm Events heat wave record, 1996 to 2025
Hurricane		events per year					1851 to 2024 (Atlantic); 1949 to 2024 (Pacific)	see B1-f	Not Applicable in NRI for this county; no descriptor.
Ice Storm		event-days per year					1946-12-31 to 2014-02-12 (67 years)	countywide	Not Applicable in NRI for this county; no descriptor.
Inland Flooding	0.679	event-days per year	about 0.679 days per year	Likely (from Storm Events: 15 of 30 years)	event-days in 15 of 30 years, 1996 to 2025 (50%)	19	1996 to 2023 (28 years)	see B1-f
Landslide	14.2	events per year (modeled)	about 14.2 per year	Highly likely	FEMA annualized frequency (modeled)	not shown	modeled	see B1-f
Lightning	22.7	days per year with a strike	about 22.7 days per year	Highly likely	FEMA annualized frequency (modeled)	not shown	1995 to 2023 (29 years; CONUS)	countywide
Strong Wind	0.039	events per year	about 1 in 26 years	Possible	FEMA annualized frequency (modeled)	2	1986 to 2023 (38 years)	countywide
Tornado	0.0379	events per year	about 1 in 26 years	Possible	FEMA annualized frequency (modeled)	not shown	1950 to 2023 (EF2+); 1986 to 2023 (EF0-1)	see B1-f
Volcanic Activity	0.0008	annual probability	about 1 in 1,250 years	Unlikely	FEMA annualized frequency (modeled)	not shown	modeled	see B1-f
Wildfire	0.00401	annual probability at a location	chance a given location in the county burns in a year: 0.401%	Likely (from Storm Events: 5 of 30 years)	Storm Events records in 5 of 30 years, 1996 to 2025 (16.7%)	not shown	modeled	see B1-f	Descriptor from Storm Events, not NRI.
Winter Weather	25.5	event-days per year	about 25.5 days per year	Highly likely (from Storm Events: 29 of 30 years)	event-days in 29 of 30 years, 1996 to 2025 (96.7%)	484	2005-11-12 to 2024-11-12 (19 years)	countywide

FEMA annualized frequency (modeled) is the National Risk Index v1.20 (December 2025) estimate of how often a hazard affects this county in a year; it is not recorded events divided by years, and its unit differs by hazard (events, event-days, or days with a lightning strike per year). For earthquake, wildfire, coastal flooding and tsunami the value is the chance (or number of events) at a location in the county, not across the county, so no "1 in N years" is given and the descriptor comes from Storm Events where it has a record (none for earthquake). The Methods page gives each hazard's method, from FEMA's National Risk Index Technical Documentation v1.20.

Descriptor scale used in this packet (defined per unit)

Sources: 5, 6

Unit	Descriptor	Definition
events per year	Highly likely	1 or more per year
events per year	Likely	about once in 1 to 10 years
events per year	Possible	about once in 10 to 100 years
events per year	Unlikely	less than once in 100 years
annual probability	Likely	10% to under 100% chance in a given year
annual probability	Possible	1% to under 10% chance in a given year
annual probability	Unlikely	under 1% chance in a given year
event-days (share of years)	Highly likely	event-days recorded in 90% or more of years
event-days (share of years)	Likely	event-days recorded in 10% to under 90% of years
event-days (share of years)	Possible	event-days recorded in some years but under 10% of years
lightning strike-days	Highly likely	cloud-to-ground strikes on 1 or more days per year

Intensity bands: historical frequency (Storm Events)

Source: 6

Hazard	Band	Years	Eventscounty-coded records	Years in period	Events per yearevents / years
Hail	1.00-1.99 in	1996 to 2025	2	30	0.0667
Hail	2.00 in+	1996 to 2025	0	30	0
Thunderstorm Wind (counted as NRI Strong Wind)	50-64 kt	1996 to 2025	4	30	0.133
Thunderstorm Wind (counted as NRI Strong Wind)	65 kt+	1996 to 2025	0	30	0
Thunderstorm Wind (counted as NRI Strong Wind)	unmeasured or below 50 kt	1996 to 2025	0	30	0
Tornado	EF0-1	1996 to 2025	0	30	0
Tornado	EF2-3	1996 to 2025	0	30	0
Tornado	EF4-5	1996 to 2025	0	30	0
Tornado	unrated (EFU)	1996 to 2025	0	30	0

The bands show how often events of each severity were recorded in this county, to profile how severe events have been (FEMA's probability item asks for the range of intensities).

Hail smaller than 1 inch is not counted: on 2010-01-05 the National Weather Service raised its severe-hail threshold from 3/4 inch to 1 inch, so smaller reports became less common after 2009 (NWS Service Change Notice 09-52). NRI hail frequency uses a 0.75 inch threshold.

Optional: future conditions. Not a required item in the 2025 FEMA Local Mitigation Planning Policy Guide; some states ask for it. The federal Climate Mapping for Resilience and Adaptation (CMRA) site gives county exposure to future climate conditions (https://resilience.climate.gov/).

Supports FEMA checklist item B1-f: hazards that vary across jurisdictions

Range of census tract risk within the county

Source: 5

Hazard	Tractsrated of all	NRI risk score, 0 to 100			Tracts by rating
Hazard	Tractsrated of all	Min	Median	Max	Tracts by rating
Avalanche	4 of 4	80.6	82.5	85.7	Relatively Moderate 4
Coastal Flooding	0 of 4				Not Applicable 4
Cold Wave	1 of 4	15.5	15.5	15.5	Very Low 1, No Rating 3
Drought	2 of 4	93.9	96.7	99.5	Relatively High 1, Relatively Moderate 1, No Rating 2
Earthquake	4 of 4	88.8	92.6	94.6	Relatively High 4
Hail	4 of 4	23.6	28.7	33.7	Very Low 4
Heat Wave	4 of 4	27.0	31.5	47.4	Relatively Low 4
Hurricane	0 of 4				Not Applicable 4
Ice Storm	0 of 4				Not Applicable 4
Inland Flooding	4 of 4	77.4	89.9	97.5	Very High 2, Relatively High 1, Relatively Moderate 1
Landslide	4 of 4	76.5	87.0	97.6	Relatively Moderate 2, Very Low 2
Lightning	4 of 4	72.3	76.5	85.3	Relatively High 2, Relatively Moderate 2
Strong Wind	4 of 4	45.0	51.6	68.2	Relatively Moderate 1, Relatively Low 3
Tornado	4 of 4	2.2	3.4	5.0	Very Low 4
Volcanic Activity	4 of 4	97.3	97.7	97.8	Relatively Low 4
Wildfire	4 of 4	92.1	96.4	99.2	Very High 1, Relatively High 1, Relatively Moderate 2
Winter Weather	4 of 4	98.9	99.2	99.7	Very High 4

Drought: Agriculture is all of NRI's expected annual loss for this hazard in the county, so the tract range mostly reflects where crop and livestock value is.

Rated tracts only: No Rating (score 0.0), Not Applicable and Insufficient Data tracts are counted but not used for the minimum, median and maximum.

The score ranks a tract against all U.S. tracts (100 = highest). The rating is FEMA's category for the tract's risk value, computed differently, so the two can disagree.

Frequency data for cold wave, drought, hail, heat wave, lightning, strong wind and winter weather are county-wide or coarse (49 km grid or NWS zone), the same for every jurisdiction; the tract range mostly reflects where buildings and people are (crop and livestock value where a line above names agriculture).

Each jurisdiction (starting figures from federal data)

Sources: 1, 3, 4, 6

Jurisdiction	Type	Plan status	Repetitive lossFMA RL and SRL (44 CFR 77.2); repeat-flood, any definition	Public Assistance to this jurisdictionFEMA records matched by applicant name; federal share obligated, nominal dollars	Event records naming this placeall years; since its plan	Notes
Mono County	County	Approved, expires 2030-07-13	FMA RL 0, SRL 0; any 1	$1,859,547.26	0 total; 0 since its plan	Includes $1,061,376.29 for declarations not counted as hazard incidents (DR-4482-CA).
Mammoth Lakes town	Town	Approved, expires 2030-07-13	FMA RL 0, SRL 0; any 0	$1,225,451.41	4 total; 0 since its plan	Includes $426,440.23 for declarations not counted as hazard incidents (DR-4482-CA).

Repetitive-loss counts are for whole NFIP communities, which can extend beyond this county (see the note in B2-c).

School districts and special districts get a plan clock row only.

County Public Assistance in B1-d also includes applicants filed under the county that are not jurisdictions in this plan (for example 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

Local data needed

The table below gives county-level starting figures; the plan describes impacts for each jurisdiction and its own assets.

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

County-level starter: exposure, expected annual loss and damage since the plan

Sources: 1, 2, 3, 5, 6, 7

Hazard	Building exposuremodeled dollars	Agriculture exposuremodeled dollars	Population exposedpeople	EAL buildingsmodeled dollars per year	EAL agriculturemodeled dollars per year	Cost of expected deaths and injuriesFEMA's dollar value per year, not property damage	EAL as % of exposurebuildings; agriculture where noted	Storm Events damage since 2025-07-14county-coded records, property plus crops, nominal dollars	Zone-level damage since planproperty plus crops, reported for the zone	Note
Avalanche	$3,051,007	n/a	10	$10,043	n/a	$1,324,333	0.329%		$0
Coastal Flooding										Not Applicable in NRI for this county
Cold Wave	$6,820,938	$14,633	16	under $1	under $1	under $1	under 0.0001%
Drought	n/a	$3,497,006	n/a	n/a	$939,836	n/a	26.9% (agriculture)			NRI has no building exposure for this hazard; agriculture shown
Earthquake	$8,090,389,387	n/a	13,195	$4,402,881	n/a	$686,171	0.0544%
Hail	$4,913,669,445	$12,327,443	13,147	$180	$326	$6,723	under 0.0001%
Heat Wave	$4,913,669,445	$12,327,443	13,147	$41	$5,267	$90,270	under 0.0001%
Hurricane										Not Applicable in NRI for this county
Ice Storm										Not Applicable in NRI for this county
Inland Flooding	$4,910,689,617	$1,329,892	697	$6,848,478	$13,805	$3,789	n/a (see note)			NRI counts the full building value of any census block with some flood loss; this is not the value of buildings in the floodplain. Use local FIRM overlays for B2-a/B2-b.
Landslide	$296,349,737	n/a	514	$1,797	n/a	$8,411	0.000606%	$0
Lightning	$4,913,669,445	n/a	13,147	$13,340	n/a	$97,857	0.000271%
Strong Wind	$4,913,669,445	$12,327,443	13,147	$14,566	$50	$65,787	0.000296%	$0	$0
Tornado	$4,913,669,445	$12,327,443	13,147	$4,033	$13	$1,099	under 0.0001%
Volcanic Activity	$4,913,669,445	n/a	13,147	$7,604	n/a	$4,791	0.000155%
Wildfire	$1,258,606,127	$10,257,723	5,349	$1,765,565	$51	$62,117	0.14%		$0
Winter Weather	$4,913,669,445	$12,327,443	13,147	$32,833	under $1	$273,072	0.000668%		$0

Totals since 2025-07-14 (Storm Events through 2026-06-30): 3 county-coded records, 2 with a damage value recorded (including $0), $0; 24 zone-level records, 23 with a damage value recorded (including $0), $0 reported for the zone; Public Assistance: no counted declaration since the plan.

FEMA does not split Public Assistance by hazard. A declaration mapped to several hazards is listed under each of them with its full amount, so the per-hazard column does not add up to the total; the unit total counts each declaration once.

NRI computes earthquake exposure on its own basis, so it exceeds the county building value in B2-a.

Supports FEMA checklist item B2-a: vulnerability (county context)

County context

Source: 5

Measure	Value
Population	13,147
Building value (total, not at risk)	$4,913,669,445
Agriculture value (total, not at risk)	$12,327,443
NRI risk rating (all hazards)	Relatively Low
Expected annual loss, buildings and agriculture, all hazards	$14,060,708
Expected annual loss, population equivalence, all hazards (NRI values each statistical life at $13.7M; a modeled value of expected deaths and injuries, not property damage)	$2,624,420
Social vulnerability rating	Relatively Low
Community resilience rating	Relatively High
NRI version	December 2025

FEMA's all-hazard expected annual loss adds buildings, agriculture and population equivalence; this table gives the property part and the population-equivalence part as separate rows.

Social vulnerability: higher means people are more likely to be harmed and slower to recover. Community resilience: lower means the community is less able to recover. High social vulnerability and low resilience both raise the NRI risk rating.

Supports FEMA checklist item B2-c: repetitive loss properties

Repetitive loss in this county, both definitions

Sources: 1, 4

Definition	Properties	Severe repetitive loss	Properties
Repetitive loss, FMA definition (44 CFR 77.2)	0	Severe repetitive loss, FMA definition (44 CFR 77.2)	0
Repetitive loss, NFIP insurance definition	1	Severe repetitive loss, NFIP insurance definition	0

The state NFIP coordinator's list, the source FEMA's Handbook names, often uses the NFIP insurance definition (second row).

Repeat-flood properties: county and state-level rows

Sources: 1, 4

Scope	SRL, FMAproperties	RL, NFIPproperties	Any categoryproperties	Mitigatedproperties
County total	0	1	1	0
of which: Mono County (unincorporated area)	0	1	1	0
Statewide, no county in FEMA's file	1	3	4	1

The statewide row counts properties FEMA's file gives with no county in this state; they are listed for reference and are not in this county's counts.

Repeat-flood properties by jurisdiction in the plan (NFIP community)

Sources: 1, 4

Jurisdiction	NFIP community ID	RL, FMAproperties	SRL, FMAproperties	RL, NFIPproperties	SRL, NFIPproperties	Any categoryproperties	Mitigatedproperties	Currently insuredproperties
Mono County	060194	0	0	1	0	1	0	0
Mammoth Lakes town	060724	0	0	0	0	0	0	0

Counts by occupancy group for each jurisdiction are in the Excel file, sheet "B2-c Jurisdictions".

Jurisdiction rows are whole NFIP communities and need not add up to the county total: a community that extends into another county is counted in full on each jurisdiction row, while the county table counts only its part in this county.

County repeat-flood properties by occupancy group

Sources: 1, 4

Occupancy group	RL, NFIPproperties	Any categoryproperties
single-family residential	0	0
2 to 4 unit residential	0	0
other residential	0	0
non-residential	1	1
not reported	0	0

FEMA's occupancy groups have no institutional class; institutional properties are counted in non-residential or other residential in the table by occupancy group.

FMA RL and FMA SRL are the Flood Mitigation Assistance definitions (44 CFR 77.2), the ones the FEMA Local Mitigation Planning Policy Guide cites. NFIP repetitive loss (the FEMA insurance definition) is 2 or more claims over $1,000 in 10 years, and a property can leave that group once it is mitigated. Also shown: NFIP severe repetitive loss, any category, mitigated and currently insured. The Methods page gives the OpenFEMA field details.

Counts are aggregates of FEMA's public NFIP Multiple Loss Properties file (FEMA's data date 2026-08-02; file version 2026-08-04). No property is identified. County assignment is FEMA's geocode.

In this county 0 properties are FMA repetitive loss but not NFIP repetitive loss, and 1 property is NFIP repetitive loss but not FMA repetitive loss.

Exact counts; no count suppression.

Sources

Tables cite these sources by number. The full list, for the plan's bibliography (FEMA review item A4-a):

FEMA, OpenFEMA HazardMitigationPlanStatuses v1, version 2026-09-29T134039Z, pulled 2026-09-30, https://www.fema.gov/api/open/v1/HazardMitigationPlanStatuses (API)
FEMA, OpenFEMA DisasterDeclarationsSummaries v2, version 2026-09-29T162832Z, pulled 2026-09-30, https://www.fema.gov/api/open/v2/DisasterDeclarationsSummaries (API)
FEMA, OpenFEMA PublicAssistanceFundedProjectsSummaries v1, version 2026-09-29T150754Z, pulled 2026-09-30, https://www.fema.gov/api/open/v1/PublicAssistanceFundedProjectsSummaries (API)
FEMA, OpenFEMA NfipMultipleLossProperties v1, version 2026-08-04T164045Z, pulled 2026-09-30, https://www.fema.gov/api/open/v1/NfipMultipleLossProperties (API)
FEMA, FEMA National Risk Index 1.20.0 (December 2025), county and census tract tables, version 1.20.0, pulled 2026-09-30, https://www.fema.gov/about/reports-and-data/openfema/nri/v120/NRI_Table_Counties.zip (download, 25 MB), https://www.fema.gov/about/reports-and-data/openfema/nri/v120/NRI_Table_CensusTracts.zip (download, 635 MB)
NOAA NCEI, NOAA NCEI Storm Events Database, details files (csvfiles v1.0), version c20260918, pulled 2026-09-30, https://www.ncei.noaa.gov/pub/data/swdi/stormevents/csvfiles/
NOAA National Weather Service, NWS county-public forecast zones correlation file, version bp03mr20 to bp16ap26 (11 files; newest bp16ap26), pulled 2026-09-30, https://www.weather.gov/gis/ZoneCounty
U.S. Census Bureau, Census 2024 Gazetteer, 2020 place by county, CT county-to-cousub crosswalk, version 2024-gazetteer, pulled 2026-09-30, https://www2.census.gov/geo/docs/maps-data/data/gazetteer/2024_Gazetteer/2024_Gaz_counties_national.zip, https://www2.census.gov/geo/docs/maps-data/data/gazetteer/2024_Gazetteer/2024_Gaz_cousubs_national.zip, https://www2.census.gov/geo/docs/maps-data/data/gazetteer/2024_Gazetteer/2024_Gaz_place_national.zip, https://www2.census.gov/geo/docs/maps-data/data/gazetteer/2024_Gazetteer/2024_Gaz_unsd_national.zip, https://www2.census.gov/geo/docs/maps-data/data/gazetteer/2024_Gazetteer/2024_Gaz_elsd_national.zip, https://www2.census.gov/geo/docs/maps-data/data/gazetteer/2024_Gazetteer/2024_Gaz_scsd_national.zip, https://www2.census.gov/geo/docs/reference/codes2020/national_place_by_county2020.txt, https://www2.census.gov/geo/docs/reference/ct_change/ct_cou_to_cousub_crosswalk.xlsx (used to match place names and codes; no table prints its values)

What this packet is and what the plan adds

This packet is the federal data for the plan's risk assessment, organized by the items of FEMA's Local Mitigation Plan Review Tool, Element B. Each section heading names the item its tables support; the plan and FEMA's review decide whether the item is met.

The plan adds what only the community has: local data on assets, critical facilities, development and each jurisdiction's impacts; local hazard history, including state-declared emergencies; the mitigation strategy; and adoption.

How the federal data are built: National Risk Index values are FEMA's model, not counts of events. Storm Events is more complete from 1996; zone-level records are placed by forecast zone, not by location in the county. Public Assistance for a jurisdiction is matched by applicant name. The Methods page gives every rule and the known edge cases.

OpenFEMA disclaimer

This product uses the Federal Emergency Management Agency's OpenFEMA API, but is not endorsed by FEMA. The Federal Government or FEMA cannot vouch for the data or analyses derived from these data after the data have been retrieved from the Agency's website(s).

Reuse, citation and corrections

Reuse and citation: Hazard Plain text and tables are licensed under Creative Commons Attribution 4.0 International (CC BY 4.0, https://creativecommons.org/licenses/by/4.0/); credit Hazard Plain and the release. The underlying federal data are public domain; OpenFEMA data are also subject to the OpenFEMA terms and conditions.

Cite this: Hazard Plain (2026). Mono County, CA: risk-assessment baseline packet, release 2026-10 (data as of 2026-09-30; County FIPS 06051). Automated baseline. https://hazardplain.org/ca/06051/ Built from FEMA OpenFEMA, the FEMA National Risk Index and NOAA NCEI Storm Events; source versions in the packet's Sources list.

Corrections: to report an error, name the packet, the table and what your records show. Contact: contact@hazardplain.org

Hazard Plain release 2026-10. As of 2026-09-30; Storm Events data through 2026-06-30. Automated baseline.