July 2006 Flash Flood

20th anniversary of Sabino Canyon & Coronado National Memorial flood events

During the last week of July in 2006, moisture from tropical storm Emilia moved into southern Arizona, and an anomalous quasi-stationary upper low over northwest New Mexico combined to bring periods of heavy rainfall for 5 consecutive overnight periods from July 27 to July 31. Rain gauges in the Catalina and Rincon Mountains recorded rainfall totals between 4 and 10 inches,with localized amounts up to 12 inches for the entire period. On the valley floor, rainfall ranged from 3 to 7 inches for the entire period. On the morning of July 31, a flood wave swept through the upper reaches of Sabino Canyon, triggering numerous rockslides and debris flows. Significant flows also occurred along Rincon Creek, Aqua Caliente Wash, Tanque Verde Creek, Rillito Creek, and the Santa Cruz River in Tucson, where homes and structures were flooded. Record flows occurred at Sabino Creek, Rincon Creek, and Rillito Creek at Dodge Boulevard. Detailed reports from 2006 of this event can be found on the Pima County website. In 2008, the United States Geological Survey (USGS) submitted a 103-page report titled “Debris Flows and Floods in Southeastern Arizona from Extreme Precipitation in July 2006—Magnitude,Frequency, and Sediment Delivery”.

The storm’s reach extended across southeast Arizona, striking Coronado National Memorial in Cochise County especially hard. The monument experienced its wettest day in recorded history on July 31, dumping 8.94 inches of rain and reaching an unprecedented 3-day total of 12 inches. For details on the damage, see the National Park Service’s 2010 report on the July 2006 storm.