Flash flooding is the most dramatic and drastic risk involved in desert canyoneering. Every few years, people are killed or seriously injured when they find themselves unaware of and/or unprepared for canyon flooding. Fortunately, we can avoid such tragedies by recognizing conditions with high flooding potential AND having the right knowledge and equipment to identify and mitigate a flooding situation.

Flash floods are common during heavy rains, particularly when preceded by either:

1. Excessively dry periods, which bake the dirt of the high plateaus like a clay pot, creating an impervious layer of thick, hard soil. When heavy rains hit this hard crust, the water does not soak into the soil, but instead runs off quickly down-stream to quickly create raging creeks and rivers.

2. After 2-3 days of rain, when the plateau soil becomes saturated and can no longer soak up water. Excess rain then quickly runs into the streams and rivers, sometimes building to dangerous proportions. These heavy rainstorms usually occur in July-September, but it is not uncommon for storms to drop significant rain any month of the year and cause the river to rise very quickly.

The actual "flash," or sudden build up of water, rocks, logs and other debris, may force a wave of water to come rushing through a narrow canyon like Orderville, then junction with excessive run-off in the Wall Street corridor of the Narrows, causing a "roll-through." This roll-thru carries a high density of debris and is deadly. The above images were taken in Zion by a Ranger where Oak Creek Canyon merges with the Virgin River. The accumulated effect of side canyon debris concurrently meeting already rising waters creates a highly dense water flow, unhikable and unswim-able. The two images below taken by a local hiker near North Creek in Virgin, Utah, again express the dramatic and severe nature of desert flooding.

Because flash floods are somewhat unpredictable, Zion National Park does not guarantee your safety even on the sunniest day of the year. Occasionally, however, the Park will post closure signs at the Temple of Sinawava to discourage visitors from hiking beyond the end of the Riverside Walk. We can assure you, if the Park has posted the sign pictured below, do not hike into the river.

1. Incoming storms + An unusually high river = DO NOT HIKE

2. While hiking, if

a) heavy rain begins to fall, and/or
b) the river becomes murky and colored from soil run-off upstream, and/or
c) the river's flow increases in flow and depth

immediately seek any kind of high ground 6 or more feet above river-level. If no further changes occur, hike down-canyon to the next high ground area. If conditions do change, stay where you are until high water passes. You may need to wait 24+ hours.

3. Hike out only when flood waters have receded.

4. If you have doubt about the safety of the river: Wait. Wait. Wait. You can not out-run, out-swim, or out-hike flood waters. Stay put.

5. Keep an eye out for high ground locations while hiking!

6. If you cannot get out, help cannot get in. Do not expect a rescue. Bring provisions in case of a forced, unexpected overnight stay.

7. Your safety is your responsibility!