Hazard Plain Automated baseline

Lake County, SD

Risk-assessment baseline packet

County FIPS:
46079
Release:
2026-10
Data as of:
2026-09-30
Storm Events data through:
2026-06-30

Hazard Plain is an independent product built from public federal data. It is not a FEMA document and is not reviewed or endorsed by FEMA or any state agency.

Hazard Plain release 2026-10, as of 2026-09-30.

Summary

Plan status as of 2026-09-30: Approved, expires 2028-04-17. Plan: Lake County, SD Hazard Mitigation Plan 2023 (FEMA plan 108751), approved 2023-04-18.

Since the plan was approved on 2023-04-18: 1 new hazard declaration (1 incident) and 71 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): Inland Flooding ($4,439,260 a year), Tornado ($3,109,962) and Cold Wave ($1,907,406).

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.

Plan clock

Status:
Approved, expires 2028-04-17
Plan:
Lake County, SD Hazard Mitigation Plan 2023 (FEMA plan 108751)
Approved:
2023-04-18
Days to expiry:
565

What changed since your last plan (approved 2023-04-18)

New federal declarations:
1 new hazard declaration (1 incident): DR-4807-SD (Severe Storms, Straight-Line Winds, and Flooding)
Storm Events records since approval:
71 records (data through 2026-06-30)
Repetitive loss now:
FMA RL 3, SRL 1 (44 CFR 77.2); any definition: 24
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

JurisdictionTypeStatusPlanApprovedExpiresDays to expirynegative = days since expiry
Lake CountyCountyApproved, expires 2028-04-17Lake County, SD Hazard Mitigation Plan 2023 (FEMA plan 108751)2023-04-182028-04-17565
Brant Lake cityCityApproved, expires 2028-04-17Lake County, SD Hazard Mitigation Plan 2023 (FEMA plan 108751)2023-04-182028-04-17565
Madison cityCityApproved, expires 2028-04-17Lake County, SD Hazard Mitigation Plan 2023 (FEMA plan 108751)2023-04-182028-04-17565
Nunda townTownApproved, expires 2028-04-17Lake County, SD Hazard Mitigation Plan 2023 (FEMA plan 108751)2023-04-182028-04-17565
Ramona townTownApproved, expires 2028-04-17Lake County, SD Hazard Mitigation Plan 2023 (FEMA plan 108751)2023-04-182028-04-17565
Wentworth villageVillageApproved, expires 2028-04-17Lake County, SD Hazard Mitigation Plan 2023 (FEMA plan 108751)2023-04-182028-04-17565

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 EALHazardNRI risk ratingEAL ratingEAL buildingsmodeled dollars per yearEAL agriculturemodeled dollars per yearCost of expected deaths and injuriesFEMA's dollar value per year, not property damageEAL total (see note)modeled dollars per yearStorm Events records, 1996 to 2026-06-30countWhy this hazard can be left outNRI Not Applicable, no declaration and no Storm Events record since 1996Storm Events coverage note
1Inland FloodingVery LowRelatively Low$4,043,746$296,123$99,392$4,439,26026
2TornadoRelatively ModerateRelatively Moderate$1,604,914$6,858$1,498,189$3,109,9628
3Cold WaveRelatively LowRelatively Moderate$39$26$1,907,342$1,907,40641
4HailRelatively LowRelatively Low$219,012$317,117$34,284$570,412138
5Strong WindRelatively LowRelatively Low$244,481$8,844$276,179$529,505157Includes 32 High Wind and 12 Strong Wind records (NOAA non-thunderstorm wind types, outside NRI's Strong Wind definition).
6Ice StormRelatively ModerateRelatively Moderate$152,172n/a$237,371$389,5435
7Winter WeatherRelatively ModerateRelatively High$136,329$249$129,121$265,699174
8Heat WaveVery LowRelatively Low$2,522$3$233,281$235,80523
9DroughtRelatively LowRelatively Lown/a$139,414n/a$139,41441
10WildfireVery LowVery Low$63,811$50$1,637$65,4980No recorded events in Storm Events since 1996 (data through 2026-06-30).
11EarthquakeVery LowVery Low$27,579n/a$8,461$36,040Storm Events does not record earthquakes.
12LightningVery LowVery Low$8,230n/a$18,780$27,0103
13LandslideVery LowVery Low$23n/a$263$2860No recorded events in Storm Events since 1996 (data through 2026-06-30).
HurricaneNot ApplicableNot Applicable0NRI rates hurricane Not Applicable for this county, and no counted federal declaration for this county names it (EM-3234-SD 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).

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 wildfire and landslide records (Storm Events records these hazards only in part).

Not applicable to this county per NRI, with no federal declaration and no Storm Events record since 1996: avalanche, coastal flooding, tsunami and volcanic activity. 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

HazardHighest-rated census tractsNRI risk rating, score 0 to 100
Earthquaketract 9602.01 (Very Low, 32.5); tract 9602.02 (Very Low, 25.6); tract 9601 (Very Low, 24.4)
Hurricaneno tract has a National Risk Index rating for this hazard
Landslidetract 9603 (Relatively Low, 84.4); tract 9601 (Relatively Low, 81.6); tract 9602.01 (Very Low, 44.7)
Tornadotract 9603 (Very High, 99.2); tract 9602.01 (Very High, 99.2); tract 9602.02 (Very High, 97.8)
Wildfiretract 9601 (Relatively Moderate, 90.7); tract 9603 (Relatively Low, 87.4); tract 9602.01 (Relatively Low, 81.4)

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 9602.01 is Census Tract 9602.01). 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

HazardScaleRecordscount and yearsObserved rangeWorst recorded eventMost damaging (when different)How it applies to jurisdictionsNote
Cold/Wind Chill, Extreme Cold/Wind Chillwind chill41 records, 1996 to 2025 (41 zone-level)1 day to 5 days (median 2 days); 37 with a recorded value5 consecutive days, 2024-01-12 to 2024-01-16, zone-levelCountywide (zone-level records).
Frost/Freeze (outside NRI's Cold Wave definition)crop damage0
DroughtU.S. Drought Monitor scale (D0 to D4)41 records, 1999 to 2026 (41 zone-level)15 days to 304 days (median 92 days); 9 with a recorded value304 days (10 months), 2012-07-01 to 2013-04-30, a run of 10 consecutive Storm Events drought records, zone-levelDrought, 2021-07-01, property not reported; $3,900,000 crops (zone total, 2021 dollars)Countywide (zone-level records).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.
EarthquakeModified Mercalli (local data)0Storm Events does not record earthquakes; the USGS earthquake catalog is the source.
Hailhail size (inches)150 records, 1958 to 20240.75 in to 4 in (median 1 in); 150 with a recorded value4 in hail, 2000-07-11Event records naming jurisdictions in the plan: Madison city (48 records), Ramona town (17 records), Nunda town (9 records), Wentworth village (6 records).
Excessive Heat, Heatheat index (in event narratives)23 records, 2011 to 2026 (23 zone-level)1 day to 6 days (median 2 days); 22 with a recorded value6 consecutive days, 2012-07-19 to 2012-07-24, zone-levelCountywide (zone-level records).
Hurricane, Tropical Storm, Tropical DepressionSaffir-Simpson0Storm 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 StormSperry-Piltz ice scale (local data)5 records, 1996 to 2022 (5 zone-level)Ice Storm, 1996-11-14, $100,000 property; crops not reported (1996 dollars); NWS zone SDZ055Countywide (zone-level records).
Flash Flood, Flood, Lakeshore Flooddamage and flood days (flood depth: FIRM)26 records, 1997 to 2024 (2 zone-level)Flood, 2019-06-01, $0 property; $27,080,000 crops (2019 dollars)Event records naming jurisdictions in the plan: Madison city (7 records), Ramona town (3 records), Nunda town (1 record). Zone-level records (2) 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 Flownone (count and damage only)0
Lightningannualized frequency (the measure FEMA's Local Mitigation Planning Handbook names)3 records, 1996 to 2005Lightning, 2000-05-17, $1,000 property; crops not reported (2000 dollars)Event records naming jurisdictions in the plan: Madison city (2 records).Storm Events lists lightning with damage or casualties.
High Wind and Strong Wind (outside NRI's Strong Wind definition)wind speed (kt and mph)44 records, 1996 to 2026 (44 zone-level)31 kt (36 mph) to 63 kt (72 mph) (median 50 kt (58 mph)); 43 with a recorded value63 kt (72 mph), measurement type not recorded, High Wind, 1997-04-06; NWS zone SDZ055High Wind, 1996-10-29, $50,000 property; crops not reported (zone total, 1996 dollars)Countywide (zone-level records).
Thunderstorm Windwind speed (kt and mph)130 records, 1958 to 202550 kt (58 mph) to 96 kt (110 mph) (median 56 kt (64 mph)); 119 with a recorded value96 kt (110 mph) estimated gust, Thunderstorm Wind, 2022-05-12Thunderstorm Wind, 2000-07-11, $500,000 property; crops not reported (2000 dollars)Event records naming jurisdictions in the plan: Madison city (42 records), Ramona town (9 records), Wentworth village (8 records), Nunda town (7 records).
TornadoEnhanced Fujita (Fujita before Feb 2007)24 records, 1956 to 2021F/EF0 to F/EF3 (median F/EF1); 22 with a recorded valueF3 tornado, 1970-06-15, 200 yd wide, $250,000 property; crops not recorded (1970 dollars)Tornado, 1992-08-09, $2,500,000 property; crops not recorded (1992 dollars)Event records naming jurisdictions in the plan: Madison city (1 record), Nunda town (1 record), Ramona town (1 record), Wentworth village (1 record).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).
Wildfireacres burned (local data)0
Winter Storm, Heavy Snow, Blizzard, Lake-Effect Snow, Winter Weather, Sleetnone in data (snowfall: local data)174 records, 1996 to 2026 (174 zone-level)Blizzard, 2019-04-11, $2,880,000 property; $0 crops (2019 dollars); NWS zone SDZ055Countywide (zone-level records).

In event narratives only (local data needed): wind chill, temperature, heat index, ice thickness, acres burned and snow depth; any physical measure of debris flow and lightning.

Storm Events records are more complete after 1996; before 1996 only Tornado (from 1950), Hail and Thunderstorm Wind (from 1955) exist. Zone-level records from zones that 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: 20 declarations covering 17 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

DeclaredIncident beganFEMA numberTypeTitleMapped hazardCounty Public Assistancefederal share obligated, nominal dollarsFlagsNotes
2024-08-152024-06-16DR-4807-SDMajor disasterSevere Storms, Straight-Line Winds, and FloodingInland Flooding (primary); also designated: Strong Wind$292,165.22new since last plan; within last 5 years
2022-06-292022-05-12DR-4656-SDMajor disasterSevere Storm, Straight-Line Winds, Tornadoes, and FloodingInland Flooding; Strong Wind; Tornado$2,033,608.77in the 12 months before plan approval; within last 5 years
2020-04-052020-01-20DR-4527-SDMajor disasterCOVID-19 PandemicNon-natural, not countedno Public Assistance recorded
2020-03-132020-01-20EM-3475-SDEmergencyCOVID-19Non-natural, not countedno Public Assistance recordedsame incident as DR-4527
2019-11-182019-09-09DR-4469-SDMajor disasterSevere Storms, Tornadoes, and FloodingInland Flooding; Tornado$7,322,048.57
2019-06-072019-03-13DR-4440-SDMajor disasterSevere Winter Storm, Snowstorm, and FloodingInland Flooding (primary); also designated: Winter Weather$982,854.55
2011-05-132011-03-11DR-1984-SDMajor disasterFloodingInland Flooding$239,099.48
2010-11-022010-09-22DR-1947-SDMajor disasterSevere Storms and FloodingInland Flooding$373,273.65
2010-05-132010-03-10DR-1915-SDMajor disasterFloodingInland Flooding$111,323.12
2007-05-222007-05-04DR-1702-SDMajor disasterSevere Storms, Tornadoes, and FloodingInland Flooding; Tornado$168,189.89
2005-09-102005-09-06EM-3234-SDEmergencyHurricane Katrina EvacuationHurricane: evacuation support, not a local hazard event; not countedno Public Assistance recorded
1997-04-071997-02-03DR-1173-SDMajor disasterSevere Flooding, Sever Winter Storms,Heavy Rains High WindsInland Flooding (primary); also designated: Strong Wind, Winter Weatherno Public Assistance recorded
1997-02-281996-11-13DR-1161-SDMajor disasterSevere Winter StormWinter Weatherno Public Assistance recorded
1997-01-101997-01-03DR-1156-SDMajor disasterSevere Winter Storms and Blizzard ConditionsWinter Weatherno Public Assistance recorded
1996-01-051995-10-22DR-1075-SDMajor disasterSevere Winter StormWinter Weatherno Public Assistance recorded
1995-05-261995-03-01DR-1052-SDMajor disasterFloodingInland Floodingno Public Assistance recorded
1993-07-191993-05-06DR-999-SDMajor disasterSevere Storms, Tornadoes & FloodingInland Flooding; Tornadono Public Assistance recorded
1984-07-191984-06-11DR-717-SDMajor disasterSevere Storms & FloodingInland Floodingno Public Assistance recorded
1976-06-171976-06-17EM-3015-SDEmergencyDroughtDroughtno Public Assistance recorded
1969-04-181969-04-18DR-257-SDMajor disasterFloodingInland Floodingno Public Assistance recorded

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

DeclaredIncident beganFEMA numberTypeTitleMapped hazard
1962-07-271962-07-27DR-132-SDMajor disasterFloods & TornadoesInland Flooding (primary); also designated: Tornado
1960-04-081960-04-08DR-99-SDMajor disasterFloodsInland Flooding
1954-07-311954-07-31DR-20-SDMajor disasterFloodInland 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.

8 Fire Management declarations (1974-07-08 to 1994-08-16) FEMA filed as Statewide with no county; each names one local fire. Listed on the state page.

Public Assistance filed under this county for declarations that do not list it: 10 rows, $5,604,358.77

Sources: 2, 3

FEMA numberDeclaredTitleApplicantPA obligatedfederal share obligated, nominal dollars
DR-4689-SD2023-02-27Severe Winter Storms and SnowstormEast River Electric Cooperative$530,855.52
DR-4664-SD2022-08-02Severe Storm, Straight-Line Winds, Tornadoes, and FloodingEast River Electric Cooperative$34,321.01
DR-4467-SD2019-10-07Severe Storms, Tornadoes, and FloodingEast River Electric Cooperative$6,483.35
DR-4233-SD2015-07-30Severe Storms, Tornadoes, Straight-Line Winds, and FloodingEast River Electric Cooperative$24,618.14
DR-4137-SD2013-08-02Severe Storms, Tornadoes, and FloodingEast River Electric Cooperative$39,908.42
DR-4115-SD2013-05-10Severe Winter Storm and SnowstormEast River Electric Cooperative$84,666.86
DR-1938-SD2010-09-23Severe Storms and FloodingEast River Electric Cooperative$12,634.60
DR-1887-SD2010-03-10Severe Winter StormEast River Electric Cooperative$84,751.32
DR-1620-SD2005-12-20Severe Winter StormEast River Electric Cooperative$4,703,593.77
DR-1596-SD2005-07-22Severe StormEast River Electric Cooperative$82,525.78

FEMA's Public Assistance summaries file these applicants under this county, but FEMA's declaration rows for these disasters do not designate it (an electric cooperative or district serving several counties, for example). Not in any declaration row above and not counted.

Public Assistance not placed in any South Dakota county: 15 rows, $522,360.71; listed on the South Dakota state page.

Source: 3

Previous occurrences by hazard, with explicit no-event rows

Sources: 2, 6, 7

HazardStorm Events records, all years on file(years in the Period column)Since plan approvalrecordsIn the 12 months before plan approvalrecordsLast 5 yearsrecordsDeclared incidents, all yearsseparate disastersDeclared since approvalseparate disastersPeriodStatement
Cold Wave417214001996 to 2026-06-30
Drought4114016101996 to 2026-06-30
Earthquake000000Storm Events does not record earthquakes; the USGS earthquake catalog is the source.
Hail15041014001955 to 2026-06-30
Heat Wave2314014001996 to 2026-06-30
Hurricane0000001996 to 2026-06-30No recorded events, 1996 to 2026-06-30, NOAA NCEI Storm Events
Ice Storm5011001996 to 2026-06-30
Inland Flooding262021311996 to 2026-06-30
Landslide0000001996 to 2026-06-30No recorded events, 1996 to 2026-06-30, NOAA NCEI Storm Events
Lightning3000001996 to 2026-06-30
Strong Wind174191437311955 to 2026-06-30Includes 32 High Wind and 12 Strong Wind records.
Tornado24000401950 to 2026-06-30
Wildfire0000001996 to 2026-06-30No recorded events, 1996 to 2026-06-30, NOAA NCEI Storm Events
Winter Weather17411924501996 to 2026-06-30

Notable Storm Events records

Sources: 1, 6, 7

DateEvent typeMagnitude or extentDamagenominal dollarsDeaths, injuriesdirect onlyLocationFlagsWhy listed
2024-01-12Extreme Cold/Wind Chilldamage not reported0, 0NWS zone SDZ055 (LAKE), zone-levelnew since last plan; within last 5 yearsB1-c worst recorded: Cold/Wind Chill, Extreme Cold/Wind Chill
2022-05-12Thunderstorm Wind96 kt (110 mph) estimated gustproperty not reported; $0 crops (2022 dollars)0, 0MADISONin the 12 months before plan approval; within last 5 yearsB1-c worst recorded: Thunderstorm Wind
2019-06-01Flood$0 property; $27,080,000 crops (2019 dollars)0, 0ORLAND to CHESTERB1-c worst recorded: Flash Flood, Flood, Lakeshore Flood
2019-04-11Blizzard$2,880,000 property; $0 crops (zone total, 2019 dollars)0, 0NWS zone SDZ055 (LAKE), zone-levelB1-c worst recorded: Winter Storm, Heavy Snow, Blizzard, Lake-Effect Snow, Winter Weather, Sleet
2012-07-19Excessive Heat$0 property; $0 crops (zone total, 2012 dollars)0, 0NWS zone SDZ055 (LAKE), zone-levelB1-c worst recorded: Excessive Heat, Heat
2012-07-01Drought$0 property; crops not reported (zone total, 2012 dollars)0, 0NWS zone SDZ055 (LAKE), zone-levelB1-c worst recorded: Drought
2012-05-05Flash Flood$2,000,000 property; $0 crops (2012 dollars)1, 0ORLAND to CHESTERdeaths or injuries recorded
2000-07-11Hail4 in$500,000 property; $1,000,000 crops (2000 dollars)0, 0COUNTYWIDEB1-c worst recorded: Hail
1997-04-06High Wind63 kt (72 mph), measurement type not recorded$10,000 property; crops not reported (zone total, 1997 dollars)0, 0NWS zone SDZ055 (LAKE), zone-levelB1-c worst recorded: High Wind and Strong Wind
1996-11-14Ice Storm$100,000 property; crops not reported (zone total, 1996 dollars)0, 0NWS zone SDZ055 (LAKE), zone-levelB1-c worst recorded: Ice Storm
1996-01-17Blizzard$40,000 property; crops not reported (zone total, 1996 dollars)0, 1NWS zone SDZ055 (LAKE), zone-leveldeaths or injuries recorded
1970-06-15TornadoF3, 200 yd wide$250,000 property; crops not recorded (1970 dollars)0, 0location not recordedB1-c worst recorded: Tornado

The full list is in the Excel file, sheet "B1-d Storm Events history" (661 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

HazardFEMA annualized frequency (modeled)unit per rowUnitIn plain termsDescriptorDescriptor basisNRI events or days in its record period (hail, wind and tornado are area-weighted, so can be fractional)NRI periodLocationNote
Cold Wave10.2event-days per yearabout 10.2 days per yearLikelyStorm Events event-days in 19 of 30 years, 1996 to 2025 (63.3%)1942005-11-12 to 2024-11-12 (19 years)countywide
Drought8event-days per yearabout 8 days per yearLikelyStorm Events event-days in 9 of 30 years, 1996 to 2025 (30%)2942000 to 2025 (25.25 years; D3 and D4 only)countywide
Earthquake0.000305annual probability at a locationchance a given location in the county has at least minor-damage shaking in a year: 0.0305%not shownmodeledsee B1-fNo descriptor (Storm Events does not record earthquakes).
Hail5.45events per yearabout 5.45 per yearHighly likelyFEMA annualized frequency (modeled)206.9 (modeled)1986 to 2023 (38 years)countywide
Heat Wave4.32event-days per yearabout 4.32 days per yearLikelyStorm Events event-days in 8 of 30 years, 1996 to 2025 (26.7%)722005-11-12 to 2024-11-12 (19 years)countywide
Hurricaneevents per year1851 to 2024 (Atlantic)see B1-fNot Applicable in NRI for this county; no descriptor.
Ice Storm0.755event-days per yearabout 0.755 days per yearLikelyStorm Events event-days in 4 of 30 years, 1996 to 2025 (13.3%)511946-12-31 to 2014-02-12 (67 years)countywide
Inland Flooding0.679event-days per yearabout 0.679 days per yearLikelyStorm Events event-days in 10 of 30 years, 1996 to 2025 (33.3%)191996 to 2023 (28 years)see B1-f
Landslide0.0607events per year (modeled)about 1 in 16 yearsPossibleFEMA annualized frequency (modeled)not shownmodeledsee B1-f
Lightning36.1days per year with a strikeabout 36.1 days per yearHighly likelyFEMA annualized frequency (modeled)not shown1995 to 2023 (29 years; CONUS)countywide
Strong Wind3.63events per yearabout 3.63 per yearHighly likelyFEMA annualized frequency (modeled)1381986 to 2023 (38 years)countywide
Tornado0.432events per yearabout 1 in 2 yearsLikelyFEMA annualized frequency (modeled)not shown1950 to 2023 (EF2+); 1986 to 2023 (EF0-1)see B1-f
Wildfire0.000461annual probability at a locationchance a given location in the county burns in a year: 0.0461%Storm Events records in 0 of 30 years, 1996 to 2025 (0%)not shownmodeledsee B1-fNo descriptor: no Storm Events record 1996 to 2025
Winter Weather19.1event-days per yearabout 19.1 days per yearHighly likelyStorm Events event-days in 30 of 30 years, 1996 to 2025 (100%)3622005-11-12 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.

Where NRI gives event-days, the descriptor comes from the share of years with a Storm Events record; NRI's source records more events, so the two differ.

Descriptor scale used in this packet (defined per unit)

Sources: 5, 6

UnitDescriptorDefinition
events per yearHighly likely1 or more per year
events per yearLikelyabout once in 1 to 10 years
events per yearPossibleabout once in 10 to 100 years
events per yearUnlikelyless than once in 100 years
annual probabilityLikely10% to under 100% chance in a given year
annual probabilityPossible1% to under 10% chance in a given year
annual probabilityUnlikelyunder 1% chance in a given year
event-days (share of years)Highly likelyevent-days recorded in 90% or more of years
event-days (share of years)Likelyevent-days recorded in 10% to under 90% of years
event-days (share of years)Possibleevent-days recorded in some years but under 10% of years
lightning strike-daysHighly likelycloud-to-ground strikes on 1 or more days per year

Intensity bands: historical frequency (Storm Events)

Source: 6

HazardBandYearsEventscounty-coded recordsYears in periodEvents per yearevents / years
Hail1.00-1.99 in1996 to 202578302.6
Hail2.00 in+1996 to 20254300.133
Thunderstorm Wind (counted as NRI Strong Wind)50-64 kt1996 to 202591303.03
Thunderstorm Wind (counted as NRI Strong Wind)65 kt+1996 to 202522300.733
Thunderstorm Wind (counted as NRI Strong Wind)unmeasured or below 50 kt1996 to 20250300
TornadoEF0-11996 to 20256300.2
TornadoEF2-31996 to 20251300.0333
TornadoEF4-51996 to 20250300
Tornadounrated (EFU)1996 to 20251300.0333

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

HazardTractsrated of allNRI risk score, 0 to 100Tracts by rating
MinMedianMax
Cold Wave4 of 490.895.496.7Very High 2, Relatively High 2
Drought4 of 480.388.094.8Relatively Moderate 2, Relatively Low 2
Earthquake4 of 422.825.032.5Very Low 4
Hail4 of 482.091.697.4Relatively High 2, Relatively Moderate 2
Heat Wave4 of 451.965.870.9Relatively Moderate 3, Relatively Low 1
Hurricane0 of 4Not Applicable 4
Ice Storm4 of 495.797.197.7Very High 1, Relatively High 3
Inland Flooding4 of 452.779.791.9Relatively High 2, Relatively Moderate 2
Landslide4 of 437.663.184.4Relatively Low 2, Very Low 2
Lightning4 of 429.736.039.8Relatively Low 4
Strong Wind4 of 492.494.095.4Relatively High 4
Tornado4 of 497.598.599.2Very High 4
Wildfire4 of 471.984.490.7Relatively Moderate 1, Relatively Low 3
Winter Weather4 of 498.799.099.3Very 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.

Hail: Agriculture is 56% 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, ice storm, 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

JurisdictionTypePlan statusRepetitive lossFMA RL and SRL (44 CFR 77.2); repeat-flood, any definitionPublic Assistance to this jurisdictionFEMA records matched by applicant name; federal share obligated, nominal dollarsEvent records naming this placeall years; since its planNotes
Lake CountyCountyApproved, expires 2028-04-17FMA RL 3, SRL 1; any 6$310,603.050 total; 0 since its plan
Brant Lake cityCityApproved, expires 2028-04-17no Public Assistance recorded0 total; 0 since its planNo NFIP community ID on this jurisdiction's plan row.
Madison cityCityApproved, expires 2028-04-17FMA RL 0, SRL 0; any 18$6,981,023.75100 total; 1 since its plan
Nunda townTownApproved, expires 2028-04-17FMA RL 0, SRL 0; any 0no Public Assistance recorded18 total; 1 since its plan
Ramona townTownApproved, expires 2028-04-17FMA RL 0, SRL 0; any 0$3,716.6430 total; 2 since its plan
Wentworth villageVillageApproved, expires 2028-04-17FMA RL 0, SRL 0; any 0no Public Assistance recorded15 total; 0 since its plan

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

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

HazardBuilding exposuremodeled dollarsAgriculture exposuremodeled dollarsPopulation exposedpeopleEAL buildingsmodeled dollars per yearEAL agriculturemodeled dollars per yearCost of expected deaths and injuriesFEMA's dollar value per year, not property damageEAL as % of exposurebuildings; agriculture where notedStorm Events damage since 2023-04-18county-coded records, property plus crops, nominal dollarsZone-level damage since planproperty plus crops, reported for the zonePublic Assistance since plannominal dollars; see noteNote
Cold Wave$5,578,227,109$208,365,94211,059$39$26$1,907,342under 0.0001%$0
Droughtn/a$55,098,838n/an/a$139,414n/a0.253% (agriculture)$732,000NRI has no building exposure for this hazard; agriculture shown
Earthquake$9,791,744,247n/a11,059$27,579n/a$8,4610.000282%
Hail$5,578,227,109$208,365,94211,059$219,012$317,117$34,2840.00393%
Heat Wave$5,578,227,109$208,365,94211,059$2,522$3$233,281under 0.0001%
HurricaneNot Applicable in NRI for this county
Ice Storm$5,578,227,109n/a11,059$152,172n/a$237,3710.00273%
Inland Flooding$5,567,167,396$16,933,134511$4,043,746$296,123$99,392n/a (see note)$750,000$292,165.22NRI 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$23,615,829n/a38$23n/a$263under 0.0001%
Lightning$5,578,227,109n/a11,059$8,230n/a$18,7800.000148%
Strong Wind$5,578,227,109$208,365,94211,059$244,481$8,844$276,1790.00438%$12,000$0$292,165.22
Tornado$5,578,227,109$208,365,94211,059$1,604,914$6,858$1,498,1890.0288%
Wildfire$999,994,311$33,642,1292,124$63,811$50$1,6370.00638%
Winter Weather$5,578,227,109$208,365,94211,059$136,329$249$129,1210.00244%$0

Totals since 2023-04-18 (Storm Events through 2026-06-30): 9 county-coded records, 3 with a damage value recorded (including $0), $762,000; 62 zone-level records, 11 with a damage value recorded (including $0), $732,000 reported for the zone; Public Assistance: $292,165.22 on 1 counted declaration.

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

MeasureValue
Population11,059
Building value (total, not at risk)$5,578,227,109
Agriculture value (total, not at risk)$208,365,942
NRI risk rating (all hazards)Very Low
Expected annual loss, buildings and agriculture, all hazards$7,271,540
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)$4,444,301
Social vulnerability ratingRelatively Low
Community resilience ratingRelatively High
NRI versionDecember 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

DefinitionPropertiesSevere repetitive lossProperties
Repetitive loss, FMA definition (44 CFR 77.2)3Severe repetitive loss, FMA definition (44 CFR 77.2)1
Repetitive loss, NFIP insurance definition24Severe repetitive loss, NFIP insurance definition1

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

ScopeRL, FMApropertiesSRL, FMApropertiesRL, NFIPpropertiesSRL, NFIPpropertiesAny categorypropertiesMitigatedpropertiesCurrently insuredproperties
County total3124124012
of which: Madison city0018018012
of which: Lake County (unincorporated area)3161600
Statewide, no county in FEMA's file0010100

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

JurisdictionNFIP community IDRL, FMApropertiesSRL, FMApropertiesRL, NFIPpropertiesSRL, NFIPpropertiesAny categorypropertiesMitigatedpropertiesCurrently insuredproperties
Lake County4602763161600
Madison city4600440018018012
Nunda town4603070000000
Ramona town4601340000000
Wentworth village4603080000000

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 groupRL, FMApropertiesSRL, FMApropertiesRL, NFIPpropertiesSRL, NFIPpropertiesAny categorypropertiesMitigatedpropertiesCurrently insuredproperties
single-family residential3123123011
2 to 4 unit residential0010101
other residential0000000
non-residential0000000
not reported0000000

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 21 properties are 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):

  1. FEMA, OpenFEMA HazardMitigationPlanStatuses v1, version 2026-09-29T134039Z, pulled 2026-09-30, https://www.fema.gov/api/open/v1/HazardMitigationPlanStatuses (API)
  2. FEMA, OpenFEMA DisasterDeclarationsSummaries v2, version 2026-09-29T162832Z, pulled 2026-09-30, https://www.fema.gov/api/open/v2/DisasterDeclarationsSummaries (API)
  3. FEMA, OpenFEMA PublicAssistanceFundedProjectsSummaries v1, version 2026-09-29T150754Z, pulled 2026-09-30, https://www.fema.gov/api/open/v1/PublicAssistanceFundedProjectsSummaries (API)
  4. FEMA, OpenFEMA NfipMultipleLossProperties v1, version 2026-08-04T164045Z, pulled 2026-09-30, https://www.fema.gov/api/open/v1/NfipMultipleLossProperties (API)
  5. 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)
  6. 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/
  7. 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
  8. 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 (the summary on page 1 says how it is organized); the plan and FEMA's review decide whether each 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). Lake County, SD: risk-assessment baseline packet, release 2026-10 (data as of 2026-09-30; County FIPS 46079). Automated baseline. https://hazardplain.org/sd/46079/ 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: [email protected]