2,838
Recorded events
321
Counties affected
151
Direct deaths
$1.4B
Property damage
2,838 debris flow events are recorded across 321 U.S. counties between 1996 and 2026.
Systematic records for this hazard begin in 1996 — earlier gaps reflect reporting practice, not calm weather.
Most affected
Top counties for debris flow
| Rank | County | Events | Deaths | Damage |
|---|---|---|---|---|
| #1 | Sonoma County, California | 60 | 0 | $16K |
| #2 | Santa Cruz County, California | 51 | 0 | $117K |
| #3 | Kern County, California | 51 | 0 | $152K |
| #4 | San Bernardino County, California | 50 | 1 | $6.6M |
| #5 | Fresno County, California | 40 | 0 | $200 |
| #6 | Chelan County, Washington | 36 | 0 | $1.1M |
| #7 | Garfield County, Colorado | 34 | 0 | $153.4M |
| #8 | Okanogan County, Washington | 34 | 0 | $259K |
| #9 | San Miguel County, Colorado | 34 | 0 | $540K |
| #10 | Monterey County, California | 32 | 0 | $10.1M |
| #11 | San Diego County, California | 30 | 0 | $2.1M |
| #12 | Mariposa County, California | 30 | 2 | $815K |
| #13 | San Juan County, Utah | 28 | 0 | $67K |
| #14 | Riverside County, California | 27 | 0 | $3K |
| #15 | Pitkin County, Colorado | 25 | 0 | $897K |
| #16 | Rio Blanco County, Colorado | 25 | 0 | $62K |
| #17 | Marin County, California | 24 | 0 | $2.0M |
| #18 | Santa Clara County, California | 24 | 0 | $0 |
| #19 | Los Angeles County, California | 24 | 0 | $0 |
| #20 | Utuado Municipio, Puerto Rico | 22 | 0 | $32K |
| #21 | Mono County, California | 20 | 0 | $41K |
| #22 | Mesa County, Colorado | 19 | 3 | $219K |
| #23 | Napa County, California | 19 | 0 | $0 |
| #24 | San Mateo County, California | 18 | 0 | $0 |
| #25 | Ouray County, Colorado | 17 | 0 | $551K |