South Dakota inland flooding risk
Minnehaha County has the highest inland flooding risk in South Dakota, scoring 85.5 out of 100 — rated "Relatively Moderate" by FEMA's National Risk Index. Recorded inland flooding events across South Dakota have decreased 63% over the past five years compared to the prior five-year period.
| # | County | NRI score | Rating |
NOAA events 2016–2026 |
|---|---|---|---|---|
| 1 | Minnehaha County | 85.5 | Relatively Moderate | 159 |
| 2 | Pennington County | 75.6 | Relatively Moderate | 32 |
| 3 | Codington County | 65.2 | Relatively Low | 65 |
| 4 | Brown County | 63.1 | Relatively Low | 79 |
| 5 | McCook County | 58.4 | Relatively Low | 14 |
| 6 | Yankton County | 57.3 | Relatively Low | 49 |
| 7 | Lawrence County | 57.1 | Relatively Low | 7 |
| 8 | Lincoln County | 56.6 | Relatively Low | 86 |
| 9 | Meade County | 51.9 | Relatively Low | 17 |
| 10 | Brookings County | 48.4 | Relatively Low | 94 |
| 11 | Union County | 47.5 | Relatively Low | 107 |
| 12 | Beadle County | 45.6 | Relatively Low | 39 |
| 13 | Fall River County | 41.5 | Relatively Low | 4 |
| 14 | Charles Mix County | 40.5 | Relatively Low | 50 |
| 15 | Roberts County | 38 | Relatively Low | 16 |
| 16 | Tripp County | 37.1 | Relatively Low | 14 |
| 17 | Davison County | 35.9 | Relatively Low | 45 |
| 18 | Hutchinson County | 35.2 | Relatively Low | 64 |
| 19 | Walworth County | 34.8 | Very Low | 7 |
| 20 | Lake County | 34.1 | Very Low | 12 |
| 21 | Butte County | 33.4 | Very Low | 7 |
| 22 | Hughes County | 32.6 | Very Low | 13 |
| 23 | Lyman County | 29.1 | Very Low | 16 |
| 24 | Clay County | 28.7 | Very Low | 28 |
| 25 | Brule County | 28.6 | Very Low | 13 |
| 26 | Todd County | 28.3 | Very Low | 5 |
| 27 | Turner County | 26.7 | Very Low | 44 |
| 28 | Moody County | 26.1 | Very Low | 77 |
| 29 | Spink County | 25.3 | Very Low | 43 |
| 30 | Haakon County | 22 | Very Low | 11 |
| 31 | Day County | 20 | Very Low | 9 |
| 32 | Stanley County | 20 | Very Low | 11 |
| 33 | Custer County | 19.3 | Very Low | 12 |
| 34 | Oglala Lakota County | 19 | Very Low | 15 |
| 35 | Dewey County | 17.4 | Very Low | 9 |
| 36 | Grant County | 17.3 | Very Low | 23 |
| 37 | Corson County | 16.1 | Very Low | 21 |
| 38 | Hamlin County | 16 | Very Low | 38 |
| 39 | Gregory County | 15.4 | Very Low | 7 |
| 40 | Hanson County | 15 | Very Low | 33 |
| 41 | Potter County | 14.6 | Very Low | 6 |
| 42 | Sully County | 14.1 | Very Low | 4 |
| 43 | Jackson County | 13.6 | Very Low | 12 |
| 44 | Aurora County | 13 | Very Low | 16 |
| 45 | Hyde County | 11.5 | Very Low | 6 |
| 46 | Buffalo County | 10.8 | Very Low | 5 |
| 47 | Douglas County | 10.5 | Very Low | 10 |
| 48 | Marshall County | 10.4 | Very Low | 10 |
| 49 | Kingsbury County | 9.4 | Very Low | 8 |
| 50 | Deuel County | 9.3 | Very Low | 8 |
| 51 | Bon Homme County | 8.9 | Very Low | 80 |
| 52 | Ziebach County | 8.9 | Very Low | 11 |
| 53 | Campbell County | 8.7 | Very Low | 8 |
| 54 | Jerauld County | 8.4 | Very Low | 3 |
| 55 | Mellette County | 8.1 | Very Low | 5 |
| 56 | Edmunds County | 8 | Very Low | 7 |
| 57 | McPherson County | 8 | Very Low | 10 |
| 58 | Faulk County | 6.8 | Very Low | 6 |
| 59 | Hand County | 6.2 | Very Low | 14 |
| 60 | Sanborn County | 6.2 | Very Low | 60 |
| 61 | Clark County | 5.4 | Very Low | 8 |
| 62 | Jones County | 4.9 | Very Low | 13 |
| 63 | Perkins County | 4.7 | Very Low | 4 |
| 64 | Bennett County | 4.3 | Very Low | 5 |
| 65 | Miner County | 4.2 | Very Low | 4 |
| 66 | Harding County | 3.5 | Very Low | 5 |
Source: FEMA National Risk Index v1.20.0, December 2025. Scores are 0–100 percentile rankings among all US counties. See the methodology page for definitions. Download the full CSV for all counties.
Inland Flooding risk nationally:
Other hazard risks in South Dakota:
Frequently asked questions
What is the highest inland flooding risk county in South Dakota?
Minnehaha County, SD has the highest inland flooding risk in South Dakota, with a FEMA National Risk Index score of 85.5 out of 100 (rated "Relatively Moderate").
What causes inland flooding risk in South Dakota?
Inland flooding covers riverine and surface (pluvial) flooding — the most common and costly natural disaster type in the US. High scores appear across river floodplains in the Midwest, South, and Mid-Atlantic, where legacy development in flood-prone areas and aging stormwater infrastructure concentrate risk.