FLOW
“Nothing is more dangerous than an idea, when it’s the only one we have.” -Emile Chartier Alain
March, 2022
Arizona/Mexico Borderlands
The Greek philosopher Heraclitus famously stated that “you can’t step into the same river twice,” but as I stood on a wide, sandy path near the Mexican border in Arizona, I couldn’t find a river to step in once. Eventually, I realized the “path” was the San Pedro River I had been looking for.
The San Pedro begins its journey on Mexico’s Sierra El Manzanal Mountain and traces a rare northern route through the middle of an ancient rift valley with high, flanking mountains alongside it (part of the Madrean Sky Islands Archipelago). Rainwater has flowed down the surrounding mountains and collected in the valley aquifer for millions of years, supplying the river, and an attendant ribbon of green flora, through a mostly hostile, dry desert. But the river is disappearing.
The reasons behind its disappearance are a local, polarizing controversy. It’s also of national concern as the San Pedro is the last natural, free-flowing river in the Southwest with a unique ecosystem.
As the river has descended farther underground, it’s caused alarm in some quarters, but a shrug in others. Leaving the hot desert floor to walk under an expansive, bird-filled canopy of trees, however, it’s easy to understand just how precious this place is and why it’s considered a “national treasure.”
It’s not hyperbole to call this river “critical”: millions of birds from more than 350 species in North America use the San Pedro at some point in their lives and it’s home to dozens of mammal and reptile species—some of which exist nowhere else on the planet.
The San Pedro has also co-existed with humans for 13,000 years—from prehistoric, mammoth-hunting Clovis people to several Native American cultures, to Mexicans and Americans past and present.
But escalating usage from tens of thousands of residents, businesses, and large agricultural operations over the span of mere decades has placed an unsustainable demand on the aquifer. The scant amount of rain the region receives each year cannot keep up with this demand, and water levels are dropping—more than ten feet annually in some places, and the water is not being replaced.
Despite the alarming situation, the drilling of groundwater wells around the San Pedro for new housing and other developments continues to be under-regulated due to political and ideological concerns, not physics.
The physics, however, are fairly straightforward: rainwater collects in the aquifer—the porous rock and sediment below the ground—establishing the “base flow” which feeds the river. This keeps the river flowing during dry periods. If you take out more water than is coming in by over-pumping the aquifer, the base flow recedes and the river dries up.
The Santa Cruz River in neighboring Tucson offers a stark example: it was in a similar situation in the 1950’s—a tree lined oasis—before over-pumping reduced the amount of water in the aquifer several feet below the riverbed, causing the river to disappear, and subsequently killing off all of the trees.
Issues surrounding groundwater usage is a classic Tragedy of the Commons problem. Garret Hardin, a prominent biologist and author of the seminal paper of the same name, offered a picture of why environmental problems are so difficult to solve. He asked us to imagine a pasture owned by no one and open to all for grazing livestock. The incentive for each herdsman is to graze a maximum number of cattle as it represents pure profit. But the commonly held land cannot support an infinite number of cattle, so at some point the pasture will collapse from overgrazing.
Likewise, continuous pressures from the agricultural sector, nonagricultural businesses, and real estate developments are putting the delicate San Pedro ecosystem in jeopardy.
Kathleen Ferris, a researcher who helped write the 1980 groundwater law in Arizona, put it bluntly: “You can’t grow and grow and grow on these far-flung lands on groundwater, have agriculture just continue to be such a dominant water user, and put industries anywhere you want. You have to be smarter. We have to change how we grow.”
Perhaps an acceptable answer for some could come from Nobel-Prize-winning economist Elinor Ostrom who disagreed with Hardin that “tragedy” was inevitable. She offered a host of examples where locals elsewhere effectively managed shared resources. Although Ostrom has been celebrated in certain circles for offering a path other than top-down, government control, the fact remains: common resources still need management.
To see something as critical as water take a back seat to political narratives tells us something about the power of narrative. Some residents are literally watching the river disappear, witnessing wells going dry, and are still resisting change. A re-engagement with material realities rather than only political and ideological ones, however, can open up our narratives to new information. This moves us from simple, opaque answers to more complex and transparent ones. Widening our narratives beyond our own timeframe is equally important. Whether it’s about the environment, or the meaning of our country, narratives that encompass only our own experience will be shortsighted. There are ancient stories at work, ancient movements and motivations. Taking in what has come before, as well as what could come after us, is critical for obtaining a fuller picture of reality.
Discussions of the San Pedro wouldn’t be complete, however, without reporting recent successes in restoring parts of it. Through the efforts of the Federal Government’s Bureau of Land Management (BLM), several organizations, and many concerned citizens, several miles of the river have seen marked improvement; specifically in the San Pedro Riparian Conservation area, set up by Congress in 1988. Limits on grazing and groundwater pumping, as well as collection efforts that capture storm water runoff, will put around two billion gallons back into the aquifer every year. The Bureau has also begun reintroducing beavers which were killed off in the late 1800’s and their numbers have grown since these efforts went into effect. The amount of riparian forest, grasses, and clover have all increased, and the number of migratory birds living or wintering here has taken a positive turn, making the San Pedro a global destination for bird watching. Even the nearby Santa Cruz in Tucson is seeing hints of life again, as groundwater restrictions there have eased usage on parts of the river.
What lessons can we draw from both the degradation of the river as well as its partial restoration? Although the degradation is partially due to events beyond our control—like the record-breaking drought that has plagued much of the West—the recent conservation successes point to the fact that some of it is within our control. Human actions, or lack thereof, affect the health of the river.
The fates of humans and animals who depend upon the San Pedro are intertwined. If the river is allowed to disappear completely as a result of continuing overuse, not only will a precious ecosystem be destroyed, but the groundwater beneath the river will continue to disappear as well. Human communities dependent upon this precious resource will soon follow.