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Summary

 

On the afternoon of July 15, 2017, a large debris flow and flash flood impacted the Ellison Creek drainage, north of Payson, AZ. There were 10 fatalities from a family recreating in Ellison Creek (at the Cold Springs swimming hole near the East Verde River) who were overwhelmed by the flood. This event was a tragic reminder of the threat flash flooding poses across northern Arizona.

 

Timeline

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Map showing the the Highline Burn Scar, Ellison Creek, and the Cold Springs swimming hole

Radar Estimated Storm Total Precipitation on July 15, 2017

A typical monsoonal weather pattern was in place on July 15th with a ridge of high pressure centered over the southern Great Basin and central Rocky Mountains

• 1:19 PM: Rain began over the Highline Fire Scar.


• 1:35 PM: Rain began over the lower Ellison Creek drainage and Pyeatt Draw.


• 1:52 PM: 0.5-1 inches of rain estimated across most of the scar, with isolated estimates of 1.5 inches just west of Moore Creek. An estimate 0.7-0.9 inches of rain had already fallen across most of the Ellison Creek drainage.


• 1:58 PM: Instantaneous precipitation rate estimates of 4.5-6.5 inches per hour were noted between 1:35pm-1:58pm as the storms moved through the upper Ellison Creek and Pyeatt Draw drainages.


• 2:14 PM: 1-1.5 inches of total rain estimated over the fire scar. About 1.5-1.75 inches fell near where Ellison Creek makes a turn west, and in the middle of the Pyeatt Draw basin. Approximately 0.5 inches of rain fell near the Cold Springs site.


• 2:42 PM: Light rain continued over the lower Ellison Creek drainage.


• 3:30 PM: First flash flood report was received near the juntion of the East Verde River and Ellison Creek


• 4:40 PM: Gila County Police Dispatch reported multiple ongoing water rescues on Ellison Creek.


• 6:18 PM: Flash flooding threat ended

• A flash flood wave of an estimated 5 feet rushed down Ellison Creek and into the Cold Springs Swimming Hole leading to 10 fatalities.
• Significant debris was observed along the banks of the East Verde River especially near the Water Wheel Day Use Area.

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Closure sign for the Cold Springs Swimming Hole after the tragic flash flood

Photo Taken By Jack Lloyd of the Cold Springs Swimming Hole on July 15, 2017 showing significant flash flooding occurring.

East Verde River at Water Wheel Day Use Area. More substantial debris was noted along the banks than at First Crossing. High water mark on trees was probably more like 4-4.5 feet.

Bank of East Verde River, approximately 200 yards upstream from parking lot at Water Wheel Day Use Area. Note substantial debris.

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There were four primary factors responsible for the flash flood and debris flow which rushed down Ellison Creek, impacting the Cold Springs swimming hole:

• The Highline Fire Scar: a fresh fire scar with significant area of moderate or greater burn intensity over steep terrain. The fire scar allowed for much greater runoff over the steep terrain, and provided a significant amount of debris to augment the impact of the flash flood.


• High Rainfall Rates: (1”/ 15 minutes) over the burn scar, and in the Ellison and Pyaett drainages. These rainfall rates corresponded to point return intervals of 5-10 years.


• Saturated Soils and Heavy Rainfall Totals: between (0.5 – 1.75” of rain) over the impacted area. The area soils were saturated from previous rainfall events, and the heavy rain on the 15th throughout the drainage further increased area-wide runoff.


• Slow Storm Motion: It is likely that the magnitude of the flood and carrying capacity of the flows downstream of the Highline Fire Scar were significantly increased by the direction of storm motion, starting at the highest elevations of the Fire Scar, and slowly moving downstream to Ellison Creek.

For more information on impacts and general inquiries about this event, please reference the contacts below:

• National Weather Service: Brian Klimowski, Meteorologist-in-Charge at (928) 556-9161 ext. 222 or brian.klimowski@noaa.gov
  Tony Merriman, Warning Coordination Meteorologist at (928) 556-9161 ext. 223 or tony.merriman@noaa.gov


• Gila County Emergency Management at (928) 701-1811