It's not just a break from the heat: Why an active monsoon is so crucial for desert life

On June 15, the United States Geological Survey stream flow gauge on Sycamore Creek, northeast of Fountain Hills, read zero cubic-feet-per-second (cfs).

But on Sept. 20 last year, it briefly registered 9,560 cfs. That’s virtually the same as the flow of the Colorado River at Lee’s Ferry today (9,770 cfs).

And on New Year’s Day 2022, the Sycamore gauge peaked at 1,600 cfs, a little higher than the 1,110 cfs the lower Salt River is currently flowing.

I witnessed the latter flood at Sycamore’s junction with Mesquite Wash, a major access point located a stone’s throw off the Beeline Highway, 48 miles from downtown Phoenix, and it was awesome.

These summer and winter floods flush the accumulated filth of the dry, low streamflow months down the canyon, into the Verde River, and renew the ravaged bottoms of Sycamore. This wild fluctuation of stream flows is a testament to the intensity and variability of rainfall in the Sonoran Desert.

Here’s hoping we get another monsoon like last year’s.

The wash is scarred by humanity's intrusion

My morning hike proved that even today’s zero cubic-feet-per-second flow on Sycamore is deceptive.

I started in a wide sandy wash, at the Mesquite Wash junction, that is scarred with abundant evidence of the dark side of humanity’s interaction with nature.

Fire circles full of half incinerated trash and surrounded by empty Bud Light cans and plastic water bottles are strewn around the bottomland. The amputated stumps of mesquite trees (cut up for firewood) are stained with fly-haloed piles of oxidizing excrement and flagged with toilet paper.

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Where sandy, the wash has been churned into tracked-up quicksand and, where rocky, it is blackened with rubber tire marks and occasional broken bits of vehicles.

At least today was a weekday, and I was alone; on the weekends it is like the hellish replay of a “Mad Max” movie. Vehicular noise, shouts, raucous music and fumes foul the desert air, as off-highway vehicles (OHVs) prowl the arroyo and surrounding hills.

2 miles later, it's a different story

As I walked further downstream, Sycamore’s canyon narrowed and was transformed from a dry wash, to a collection of puddles to stretches of flowing water, all in a matter of 2 miles.

Water seeped clear and cool into my shoes as I threaded my way among fluted outcrops of the billion-and-a-half-year-old, water-sculpted diorite bedrock that forced the subterranean flow to the surface and littered the streambed with desk-sized boulders.

This topography forms a natural barrier to vehicles, so the OHV tracks dropped off and then disappeared. Cardinals flash by; carrion birds circle overhead; the descending arpeggio of Canyon Wrens echoes off of the arroyo walls.

My passage sent thousands of tadpoles (rapidly metamorphosing into toads) swimming, hopping and generally churning up the water as they fled. Vortices of flashing butterflies swirled, bees and wasps swarmed the drying, downstream end of flowing sections, drawn by the deer- and javelina-tracked mud.

I still hear the occasional Doppler-effect trill of a hummingbird speeding by, even though the only obvious flowers still blooming in the June heat are a rare tuft of tiny lavender verbena on sand bars and scattered clusters of the large exotic white trumpets of the sacred datura.

Will these oases still be here when we need them?

I settle down on a sand bank in the blessed, cool shade of the sycamores, mesquite, willows, cottonwoods and walnuts and catch glimpses through them of the cactus and palo verde studded hills pressing in on every side.

I worry: Will the rains start before the stream dries up entirely? And if it does, what strategies for survival do these creatures have (estivation: the summertime equivalent of hibernation)?

This is the ultimate challenge for desert riparian life: surviving until the rains start, then not getting swept into oblivion by the floods they bring.

And all of this exacerbated by changing climate, wildfires, damming of streams and drawdown of water tables by groundwater pumping. These make incursions by four-wheelers and dirt bikes, while ugly and annoying, recede into insignificance.

These linear green oases are my shelter from the Valley’s asphyxiating summer heat where, selfishly, I dream of post-apocalyptic refuge: but will they still be here when I need them?

Rich Leveille is a retired international mineral exploration geologist who lives with his wife, Janice, in Mesa and has a passion for exploring and preserving Arizona’s wild backcountry. Reach him at raleveille@gmail.com.