4 federal flood & hurricane disasters
Share of the whole county outline, rivers and lakes included; parts FEMA hasn’t mapped count as zero.
Shaded areas are FEMA’s mapped flood hazard zones in and around Dewey County, South Dakota. Zoomed out they are simplified; at street level the map switches to FEMA’s exact layer. Tap anywhere to check that spot, or search an address above.
General flooding driven by river overflows and heavy rainfall dominates Dewey County, supported by 20 recorded flood events and 14 flash flood events over the last 30 years.
Recent history demonstrates the destructiveness of these events. In March 2019, above-normal snowpack melt and ice jamming caused significant river flooding, including the Moreau River near Whitehorse reaching major flood stage nearly 7 feet above flood level. Later, in September 2025, moderate to heavy rainfall combined with saturated soils led to the flooding of several streams and creeks, including Virgin Creek near Promise.
Property owners, residents, and real estate agents located near rivers, streams, and low-lying creeks should pay the closest attention to flood risks in Dewey County, particularly during spring snowmelt and periods of heavy autumn rainfall.
Summary written from NOAA storm reports and NFIP claims for this county. Not a prediction.
7 NOAA storm reports from Dewey County describe what happened, in the words of the forecasters who covered it. Read the South Dakota flood stories →
17 federal disaster declarations since 1976, 4 of them floods, coastal storms or hurricanes.
| Disaster | Began |
|---|---|
| Severe Winter Storm, Snowstorm, And Flooding | Mar 13, 2019 |
| Severe Winter Storm | Dec 24, 2016 |
| Severe Storms, Tornadoes, And Flooding | Jun 13, 2014 |
| Severe Winter Storm, Snowstorm, And Flooding | Oct 3, 2013 |
| Severe Storms, Tornadoes, And Flooding | Jun 16, 2010 |
| Severe Winter Storm | Jan 20, 2010 |
| Severe Storms And Flooding | Mar 11, 2009 |
| Severe Winter Storm And Record And Near Record Snow | Nov 5, 2008 |
Weather and water disasters only; most recent first. Source: OpenFEMA Disaster Declarations.
34 since 1996: 14 flash floods and 20 river or area floods.
| Event | Date | Damage |
|---|---|---|
| Flood | Sep 18, 2025 | — |
| Flood | Mar 26, 2019 | — |
| Flood | Mar 24, 2019 | — |
| Flood | May 1, 2019 | — |
| Flood | Jun 1, 2019 | — |
| Flood | Apr 1, 2019 | $198,800 |
| Flash Flood | Aug 12, 2017 | — |
| Flash Flood | Jul 22, 2016 | — |
— = no damage estimate in the record. Source: NOAA Storm Events Database.
Flood · Sep 18, 2025. Moderate to heavy rainfall occurred across a broad portion of Stanley and Dewey counties. The COOP observer 3 miles west southwest of Wendt would record a 2 day total of 4.94 while the CoCoRaHS observer in Fort Pierre received 4.06 over 3 days. This area had also received about an inch of rainfall on or around the 15th. Rainfall and saturated soils resulted in flooding of several streams and creeks, including the…
Flood · Mar 26, 2019. Much above normal winter snowfall and melt water/ice jams along with heavy rains in the middle of March brought flooding across parts of central and northeast South Dakota for late March. Rivers and creeks flooded across much of the area along with many fields and roads. The flooding damaged many of the roads and culverts across the region. Some structures were also flooded. Lake levels also rose threatening homes…
Flood · Mar 24, 2019. Much above normal snow pack melt water and ice jamming brought flooding on the the Grand, Moreau, and Bad rivers across Corson, Dewey, Jones, and Stanley counties at the end of March. The Grand River at Little Eagle rose to moderate flood stage, nearly 4 and half feet above the flood stage of 15 feet. The Moreau River near Whitehorse rose to major flood stage, almost 28 feet or 7 feet above flood stage. The Bad Ri…
Flood · May 1, 2019. March and April snowmelt and heavy rain flooding along with above normal May precipitation resulted in hundreds of thousands of acres of crops damaged or delayed/unplanted across central and northeast South Dakota. The widespread flooding continued into June with millions of dollars of loss.
National Weather Service narratives, lightly trimmed. Source: NOAA Storm Events Database.
Every colour on the map above is a place on this drawing: where the ground sits relative to the flood FEMA plans for.
If a building in Dewey County is in a high-risk zone (A or V) and its mortgage comes from a federally regulated or insured lender, or is federally backed, flood insurance is required.
Outside those zones it is optional, and often worth having: from 2014 to 2024 nearly one-third of NFIP claims came from outside the high-risk Special Flood Hazard Area. Since Risk Rating 2.0, NFIP premiums are set for each building, so the only reliable price is a quote: FloodSmart.gov or a local agent.