Enter any address in Grant County, South Dakota to see its FEMA flood zone
Flooding from heavy rainfall events dominates Grant County's flood history. Over the last 30 years, NOAA data shows 29 flood events and 14 flash flood events, with one recorded fatality. For instance, on June 25th, 2025, thunderstorms produced over three inches of rain in Milbank, leading to washed-out roads and water reaching home foundations near Ortley. Another flood event occurred on June 26th, 2025, following similar heavy rainfall.
National Flood Insurance Program (NFIP) claims data indicates that properties in Zone A have experienced the most claims, with an average payout of $6,463 and an average water depth of 2.7 feet. Claims in Zone X and X_Unshaded also show water depths, averaging 2.0 feet in X_Unshaded. Homeowners in Zone A, as well as those in Zone X and X_Unshaded, should pay close attention to flood risk information.
Summary generated from NOAA storm narratives and NFIP claim data for this county. Not predictive.
21 NOAA storm reports from this county describe what happened, in the words of the meteorologists who were there.
Grant County, South Dakota has recorded 44 flood-related events since 1996 according to NOAA's Storm Events Database, including 14 flash floods and 29 river or area floods. The county has received 22 federal disaster declarations, 10 of which involved flooding or coastal storms. Enter any address above to check its FEMA flood zone designation.
FEMA Disaster Declarations (1969–2023)
Source: OpenFEMA Disaster Declarations Summaries.
| Declaration | Type | Date |
|---|---|---|
| Flooding | Flood | Apr 9, 2023 |
| Severe Storm, Straight-line Winds, Tornadoes, And Flooding | Severe Storm | May 12, 2022 |
| Covid-19 | Biological | Jan 20, 2020 |
| Covid-19 Pandemic | Biological | Jan 20, 2020 |
| Severe Winter Storm, Snowstorm, And Flooding | Flood | Mar 13, 2019 |
| Severe Winter Storm | Severe Storm | Dec 24, 2016 |
| Severe Storms, Tornadoes, And Flooding | Severe Storm | Jun 19, 2013 |
| Flooding | Flood | Mar 11, 2011 |
| Flooding | Flood | Mar 10, 2010 |
| Severe Winter Storm | Severe Storm | Jan 20, 2010 |
NOAA Storm Events Database (1996–2025)
Source: NOAA National Weather Service Storm Events Database.
| Type | Date | Damage |
|---|---|---|
| Flood | Jun 26, 2025 | 0.00K |
| Flood | Jun 25, 2025 | 0.00K |
| Flood | Jun 13, 2025 | 0.00K |
| Flood | Aug 6, 2025 | 0.00K |
| Flood | May 7, 2024 | 0.00K |
| Flood | Apr 12, 2023 | 0.00K |
| Flood | Apr 11, 2023 | 0.00K |
| Flood | Apr 10, 2023 | 150.00K |
| Flood | Mar 22, 2019 | 0.00K |
| Flood | Jul 4, 2019 | 0.00K |
Flood — Jun 26, 2025
On June 25th, multiple thunderstorms from the morning into the early afternoon caused flooding in parts of northeast South Dakota. A CoCoRaHS observer 4 miles south-southeast of Milbank recorded 3.33 inches of rain, while the COOP observer in Milbank measured 3.25 inches. Grant County Emergency Management sent photos of washed-out roads, and a resident near Ortley documented water reaching a ho...
Flood — Jun 25, 2025
On June 25th, multiple thunderstorms from the morning into the early afternoon caused flooding in parts of northeast South Dakota. A CoCoRaHS observer 4 miles south-southeast of Milbank recorded 3.33 inches of rain, while the COOP observer in Milbank measured 3.25 inches. Grant County Emergency Management sent photos of washed-out roads, and a resident near Ortley documented water reaching a ho...
Flood — Jun 13, 2025
A broad low-pressure system brought several rounds of rain and a few strong, isolated thunderstorms to northeast South Dakota. The rain began on the morning of June 12th. A break in the rain mid-day allowed the atmosphere to destabilize, which led to stronger storms in the afternoon. One storm produced penny-sized hail 3 miles west of Blunt. Another storm in Mansfield produced penny to nickel-s...
Flood — Aug 6, 2025
Heavy thunderstorm rainfall of 2 to 4 inches on saturated soils resulted in flooding of the North Fork Whetstone River near Milbank late on the evening of August 6th.
Flood — May 7, 2024
A wet April and early May, including heavy rain producing thunderstorms on May 6th, resulted in the North Fork Whetstone River briefly rising to above flood stage during the evening of May 7th into the morning of May 8th. The nearby Milbank COOP observer recorded 3.37 inches of rain in April and an additional 1.33 inches of rain during the first week of May. The river peaked at 1056.55 feet, or...
Source: NOAA National Weather Service Storm Events Database.
Source: OpenFEMA NFIP Individual Claims (2.25M records analyzed).
FEMA assigns flood zone designations to areas in Grant County, South Dakota:
AE High Risk — 1% annual chance of flooding. Insurance required.
VE Very High Risk — Coastal flooding with wave action.
X (Shaded) Moderate Risk — 500-year floodplain.
X Low Risk — Outside major floodplains.
Properties in Grant County, South Dakota that are in FEMA-designated Special Flood Hazard Areas (zones A and V) with federally backed mortgages are required to carry flood insurance.
Even outside high-risk zones, flood insurance is recommended. From 2014 to 2024, nearly one-third of NFIP claims came from outside the high-risk Special Flood Hazard Area.
Visit FloodSmart.gov to find an agent and get a quote.