Monsoon season in the desert is a mixed bag. From June through September, life-altering rains restore and rejuvenate this parched landscape. However, these same sprinkles and rainstorms may turn into deluges, resulting in dangerous flash flooding. Back in June, Moab experienced two flash floods that were estimated to be within the 50-year-flood cycle and ended up “flashing” through town. It takes a good-sized thunderstorm to create that much flooding.

Other times in summer, one can see drifting tentacles of a thunderstorm. When there is a band of dry air below the clouds and above the ground, precipitation tends to evaporate before reaching the ground. This is called “virga” and the wispy curtains of rain are just a broken promise to the relief of moisture falling to the ground. But, when the air becomes saturated with moisture, the promise of rain is fulfilled.

Visitors new to the region may be surprised by the daily, “Chance of afternoon thunderstorms” forecast, especially on a cloudless August morning. But as the temperature begins to rise, so do the formation of thunderheads or cumulonimbus clouds. These clouds may dissipate later in the day or produce spectacular thunderstorms complete with lightning, thunder, and heavy rainfall. It’s best to treat these thunderstorms with respect and keep an eye on their progress.

When the storms do hit, depending upon the intensity of the rain, the precipitation may soak into the ground but often the rainfall runs off rocky surfaces or saturates the ground quickly. Sometimes this runoff results in spectacular flash floods or waterfalls cascading off the cliffs. Spectacular to watch, just beware of rocks and debris being carried by the floods if you’re out exploring or driving along the river.

With enough runoff, water will pool and collect in the canyon washes, but it is the potholes, sometimes called tinajas, or pools eroded into the slickrock that offer a fascinating look in an aquatic microcosm of desert life.

These natural basins vary in depth and size. While it may be tempting to splash around in one of the deeper ones, first consider how important these watering holes are to wildlife such as bighorn sheep which venture down to these areas for a drink of water or to the aquatic life that depends entirely upon these potholes for their existence.

Many of these potholes are ephemeral, temporarily holding water from a rainstorm but drying up in the heat of summer. Pothole Point in the Needles District of Canyonlands is a great area to explore these potholes which exist throughout the region.

When dry, these potholes seem devoid of any life. But just add water and within a short timeframe, life appears.

A small mite endemic to the Colorado Plateau, Paraquanothrus grahami, is one such creature which lies dormant within sediments covering the bottom of the pothole. Within minutes after moisture is added, this mite emerges from its protective chamber to feed on nematodes and other creatures also beginning to appear. In addition to the mites, fairy shrimp, clam shrimp, and tadpole shrimp – ancient looking creatures – start to hatch from eggs that have lain dormant in the sediments and soon race through a life cycle of feeding, breeding, and egg laying before the pool dries out.

The pools may also hold freshwater snails, tadpoles, and the larvae or adults of diving beetles, backswimmers, dragonflies, damselflies, and in certain pools, tiger salamanders. These tinajas are true microcosms of desert life.

Before heading out to explore potholes, watch “Ephemeral Pools of Moab ~ The Nature & Creatures of Water Potholes” with Tim Graham (of the famous mite P. grahami) available on YouTube. With great underwater shots, this short film highlights these amazing creatures within an incredible landscape. You’ll never walk or ride through another dry pothole after watching this film!