I HAD A FISHING POLE in my hands almost before I could talk. It had no hook, for safety, but this did not matter because the river nearest to my house had no fish.

I say river. What I mean is a wash of sand, flowing—can I say flowing?—down from the Tucson Mountains in southern Arizona through cacti and creosote. If you had the right kind of eyes, you could see a subtle thickening of green along the arroyo’s edges from mesquite and palo verde that knew the value of patience. My wash, the San Juan, trundled through the sprawling city to the Santa Cruz, the Gila, and finally the Colorado. Dry or drying rivers, named by Spanish conquistadors for their holy saints, and holding older names in the Tohono O’odham tongue. In O’odham, ’akimeli is “river,” though not necessarily one with water in it year-round. Desert rivers aren’t defined by the damp.

Summer always brought rain: catastrophe and celebration in one. The first monsoon storm crackled over the mountains in late June right around the feast day of San Juan Bautista, my river’s namesake. Baptism by fire and water, those storms. A good gully washer could turn sand to raging torrent in a matter of minutes. It wasn’t safe to linger, but I did anyway. Barefoot, I paddled in pools thick as chocolate and waited for the sand trout to rise.

Legend says they slumber inches beneath the surface of arroyos and emerge to mate only when water flows. I suspect it’s the thunder that wakes them, and that the incursion of paved roads into the Sonoran Desert troubles them, for the freeway’s rumbling can mimic the call.

They say it’s a recent twist of evolution. Before the 1900s, parts of the Santa Cruz River flowed perennially and harbored several species of native fish. When the river went dry, drunk down by city wells, some of those fish evolved in a hurry. So the story goes: gills traded for lungs; eyes raised on stalks; scales hardened against the heat.

Summer always brought rain: catastrophe and celebration in one.

It’s one way to grieve, I suppose, insisting that what we lost can’t be gone forever. The city remembers in different ways. At the Cortaro Farms crossing, fish swim on the sign announcing the Santa Cruz River, and farther south at Tanque Verde Wash, stainless steel trout (rainbow colors streaking their sides) spring from sculptures on either side of the road. salmo harenatus, says the plaque. Anything written in raised bronze letters has a ring of truth.

Even geology gets in on the joke. Break one rock against another in these saguaro-studded hills, and on a lucky day you might find, whisker-thin, the bones of fish. Art and story and the memories of stones together make a kind of prayer. The sand trout consoles us. Nature adapts, the legend says. Wonder persists. In hard times, life goes underground.

As a child, I cast my line again and again on the San Juan’s dry sands, hoping to glimpse a scale, a fin, a fish fat with stored water and pale from its subterranean nap. In those days my wash flowed two or three times a summer, and at least once every year enough rain fell to rouse the larger Santa Cruz. I was not the only desert dweller living in hope, for the overpasses would fill with anglers who tried one fly after another in the floodwaters, every cast a genuflection. Drop everything and go to the river; that was the rule, for we knew the water would vanish within hours, drawn down into the earth or raptured into a hungry sky.

At least one nature sanctuary in Tucson boasts a NO FISHING sign over a bridge that spans dry dirt. The sand trout are endangered, not in law, but in memory and mind. Still, we fish for them. Internet lore suggests a beer bottle cap as bait and says a sand trout hooked on a hot day will be filleted and cooked by the time it’s dragged to shore. I believe this is untrue. You need no hook at all, for the sand trout rise to no bait except the first warm drops of rain.

I never got so much as a nibble. But legend doesn’t demand proof, only an ability to wait. After all, it’s not such a strange story. Spadefoot toads sleep nearly all the year underground and rise to the sound of thunder. Horned lizards (the sand trout’s favorite snack, so they say) mimic rocks until they’re startled, when they squirt blood from their eyes. The rattlesnakes are courteous and give warning before they strike, and kindly scorpions carry their babies on their backs. Endless possibility is the gift of the desert. The sand trout lives halfway between epitaph and hope—a collective, slumbering hope for the river’s revival and the rain’s return.

These days, effluent flows in a stretch of the Santa Cruz downriver from the wastewater treatment plant. The water could be claimed elsewhere, but for now, it’s here, between the river’s banks. Cottonwoods on either side clap leaves that rival any jungle’s green. Fish swim in those waters. They arrived in Coleman coolers carried by human hands. But I like to think they were waiting all these years, just inches under the sand.