“There is always a storm…. some live through it and others are made from it.” — Shannon Alder

“Extraordinary weather begets extraordinary landscapes.”

Gentle desert rain and light winds are pleasant respites from the hot summer days and in winters can spur spectacular wildflower displays, but that is not what sculpted our desert mountains, or the Painted Canyon spires and slot canyons, or built the sand dunes, or eroded the Grand Canyon or filled ancient Lake Cahuilla. Our desert landscapes are the product of uncommon but repeated and violent storms.

Alluvial fans, the sand and rock and boulder debris left behind and extending from canyon mouths after flood events, form the foundation upon which desert cities have been built. In 1939, remnants of a hurricane reached the northwestern corner of the Coachella Valley, causing massive flooding from Mission Creek and Big and Little Morongo Canyons. Much of what was then a young Desert Hot Springs was flooded and leveled. Sand and gravel and rock covered what was once a new desert city. It was a phenomenon that had been repeated over centuries and had created the relatively flat, arguably buildable but flood-prone lands of the Coachella Valley. When the sun dried the new sand deposits, strong westerly winds pushed that sand into dunes, replenishing and renewing the Willow Hole dunes and pushing sand up into the western Indio Hills where it has created some excellent habitat for Coachella Valley fringe-toed lizards.

In 1976 another hurricane entered the Coachella Valley, sitting first over Deep Canyon and then shifting north and sitting atop Fan Hill and Thousand Palms Canyon. The alluvial fan below Deep Canyon,  flooded much of south Palm Desert. Cars and sofas floated down Highway 74, across Highway 111. On the north side of the valley flood waters laden with sand and rock careened down Thousand Palms Canyon, ripping native palms from the several palm oases and cutting the canyon down at least thirty feet lower than it had been just moments before. Palm tree trunks along with sand and water were strewn across Ramon Road and extended all the way to Interstate 10. The freeway blocked the water and debris and so created a huge lake that covered what is now the Coachella Valley National Wildlife Refuge; only the tallest dunes remained above water, appearing as a chain of white sand islands poking above a sea of murky, silt-laden water.

By eroding Thousand Palms Canyon thirty feet lower than it had been just a day before, the water table, maintained by the several traces of the San Andreas earthquake fault that bisect that canyon, was lowered by thirty feet. The remaining native palm trees along the edge of the eroded canyon, with roots that reached down a mere 10 feet or so, were then left high and dry. The palms immediately began to yellow and die. At that time the canyon was primarily owned by a corporation whose goal it was to develop the canyon into an exclusive golf resort. The native palm oases were meant to be the “draw” making this resort stand out and above the plethora of sterile, “cookie-cutter” golf resorts being planned and built across the Coachella Valley. The corporate heads acted quickly digging new wells and irrigating each and every remaining palm tree with drip irrigation that provided each tree with up to 100 gallons of water each day. The palms immediately re-greened and flourished.

The “lake” created by floodwaters inundated the sand fields and stranded any remaining fringe-toed lizards, flat-tailed horned lizards, and giant sand-treader crickets on the refugia provided by just a few tall dunes. Eventually the water receded, leaving mud flats surrounding the dunes. Higher on the alluvial fan the receding water also left huge deposits of new sand. Those sands, when dried and pushed by northwestern winds, built new sand dune systems, dunes that had not existed prior to the hurricane’s arrival. The new dunes were colonized by fringe-toed and flat-tailed horned lizards, as well as by Coachella Valley milkvetch, along with all the other native plants and critters that thrive on sand dunes. The receding waters also left fertile ground for non-native plants; high on that list of weeds were Russian thistle and Sahara mustard.

About nine years later, in the winter of 1985-86, Katie, Colin, and I arrived in the Coachella Valley. I had been given the task of implementing the newly minted, first ever-anywhere, Habitat Conservation Plan that here was focused on protecting the endangered fringe-toed lizard. The Thousand Palms Canyon golf resort never happened; the multiple earthquake faults and ever-present threat of flooding was too big a hurdle. The Nature Conservancy, then my employer, purchased the lands otherwise destined to be a golf resort and I set up my office in the “palm house” amid the Thousand Palms oasis. Each and every palm tree was still being irrigated, creating a moral conflict for me. I was tasked with protecting a natural ecosystem, yet the irrigation tubes at the base of each tree were decidedly “unnatural.” One day I received a call from the lead of a federal inventory of all important U.S. wetlands. They wanted to come to see what they had heard was one of the exemplary native palm oases in the Colorado Desert. They arrived and upon seeing the irrigation tubes immediately turned on their heels, saying they were only tasked to inventory natural wetlands.  I turned off the irrigation that day, and waited to see the result. Years later, just three palm trees had died. Apparently, after nearly a decade that included several small floods, the palms roots and their critical ground water supply had reconnected.

Over that decade since the hurricane-catalyzed flood, Russian thistle had taken over all but the most active dunes and I was directed to remove it. Faced with what appeared to be an insurmountable task, I opted to do some science first. I had two questions: what was the impact of this weed on the lizards, and was the thistle population growing, stable, or declining? Surprisingly, fringe-toed lizards were most abundant where the thistle density was moderate; the lizards found food, thermal cover, and effective escape from predators beneath Russian thistle plants. I also found that the thistle was declining on its own. Apparently, the conditions it needed were found as a result of an immediate post flood disturbance, higher soil water, higher soil nutrient environment. I left the thistle to its own trajectory, and today it still occurs there, albeit at much lower densities. The mustard continues to be a threat to all native dune species, although only during those years with ample early winter rains. In years when the winter rains hold off until mid-January or February, the native wildflowers and bugs and lizards do fine.

These two hurricanes prompted the Coachella Valley Water District to expand its mission to include flood control. Today Desert Hot Springs along with each of the cove cities has structures in place to protect lives and property from the levels of flooding experienced in 1939 and 1976. Ongoing flood control planning is occurring for Indian Avenue and for the Thousand Palms region. The challenge is that effective flood control almost always includes eliminating that vital ecosystem process of delivering new sand to the last remaining habitats for a host of species endemic to the Coachella Valley’s sand dunes. The flood control implemented for Desert Hot Springs is now “starving” the remaining otherwise protected habitats of critical sand inputs down-wind from the Morongo Canyon – Mission Creek sand sources. Over time those preserves will continue to decline in their ability to sustain dune species. The Indian Avenue and Thousand Palms flood planning process explicitly includes provisions to keep sand flowing into their respective downwind protected areas.