Romancing the River: Thinking Like a River: “…careful first to be sure we are working with the river we actually have today, not the river we thought we had a century ago” — George Sibley (Sibley’s Rivers) #ColoradoRiver #COriver #aridification

Click the link to read the article on the Sibley’s Rivers website (George Sibley):

Greetings in 2024, which promises to be an interesting year, along the Colorado River and beyond it too. May we come out of it affirmed nationally in our commitment to democratic governance, and improved in our execution of it on our river.

Back in the earlier part of the last century, the great conservationist and ecologist Aldo Leopold advised us to ‘think like a mountain’ – a large entity occupied by many life forms working together, sometimes cooperatively, sometimes competitively, but keeping the whole system in a living, dynamic balance. Remove any part – the wolves, in his story – and something else would start to go out of balance (the deer) and a kind of disorder would spread through the whole system. When intruding on an ecosystem, he was saying, tread carefully and move incrementally, stop often to observe your unfolding consequences….

Were Leopold here today, as we undertake the sobering Anthropocene task of more effective management strategies for the Colorado River we’ve created from the river we found here, he might advise us to ‘think like a river’ – being careful first to be sure we are working with the river we actually have today, not the river we thought we had a century ago when we began to develop the management strategies that finally crashed at their century mark in 2022. [ed. emphasis mine]

Am I suggesting that the river actually ‘thinks,’ like we humans (supposedly) think? No. I don’t pretend to know if anything else in the universe thinks like we think (when we choose to). But it ought to be evident, here in the Anthropocene Epoch, when we are altering – consciously or unconsciously – a lot of the planet’s systems, that we could be better at thinking things through than we seem to be, and we ought to be able to learn something about thinking things through from looking closely at the systemic behavior of things that have been working much longer at the challenge of surviving, even thriving, with a measure of sustainable grace…. Like our rambunctious river, before we went to work on it.

Watching a river (one of my favorite occupations), the first superficial observation might be: this is a stream of water that is leaving, flowing away from land that was not able to put it to use, so it is leaving the premises – usually carrying some of the land with it. This is an accurate perception of one of the river’s functions (without which, there would be no ‘downstream’), but that is not to say that the flowing stream is nothing but a drainage ditch. The flowing stream actually interacts with the land it is moving through as much as it can, through what hydrologists call ‘hyporheic exchange’ – either moving some of its water into the land it is flowing through, or picking up groundwater trickling into the stream. And it isn’t just purely water that gets exchanged both ways: the water is full of micro-organisms and dissolved and particulate minerals and gases, nutrients that also move into or out of the land.

A river’s boundary does not end at the channel margins. Even when not in flood, the river’s water reaches out laterally, beneath the riparian forest and floodplain, and vertically, into the substrate beneath the channel.

This underground world, where water originating in the river channel is percolating, in darkness, through the spaces between grains of gravel and sand, is called the hyporheic zone. The term Hyporheic means, literally, “beneath the river.” The distinguishing feature of this underground world is that surface water percolates down into it, moves through it for a while, and then reemerges from the streambed, becoming part of the surface water again further downstream.

This exchange of surface and subsurface water happens all along the river channel, giving the hyporheic water a character distinct from ordinary groundwater. And in the process, the surface water becomes changed as well.

One of the changes that happens when water enters the hyporheic zone is that it becomes cooler. We have all had the experience of going into the basement of an old house on a hot day, and noticing how cool the air can be down there. Temperatures below ground are cooler in the summer time, and more constant throughout the day. The streambed is no different.

The water flowing in the hyporheic zone becomes cooled, and when it reemerges, it cools the surface water as it mixes. This is one of the ways that a stream can remain cool in the sunlight, and cool off again in the shade after flowing through blistering sunlight.

Since the water flowing into the hyporheic zone carries dissolved substances from the surface water, including oxygen, carbon dioxide, and other nutrient substances that nurture growth of plants and fungi, there is life in this underground world. Each grain of gravel and sand becomes coated with a living film of microbes, a “biofilm,” that is nurtured by this flowing water and thrives in the absence of sunlight. Microscopic creatures, and even larger creatures, big enough to be seen by our eyes, such as copepods, tardigrades, insect larvae, tube worms, roundworms, and even juvenile fish enter, and live in, the hyporheic zone.

It is this biological activity that leads to another important function of the hyporheic zone: water filtration and purification. The streambed acts as a sand filter, physically straining out tiny particles of silt and organic matter, helping keep the surface water clear. The biofilm absorbs chemicals out of the water. Some of these chemicals nourish the microbes making up the biofilm. Other chemicals, including toxins from human pollution like road runoff, are absorbed by the biofilm, and in some cases broken down into harmless substances by the microbes.

Hydrologists call a stream picking up water from the land it’s moving through a gaining stream, and a stream that is giving some of its water to the land a losing stream. I think the latter ought to be called a ‘giving stream,’ but I guess we’ve got to go with the hydrologist terminology. (It’s Trumpthink to call the stream a ‘loser’ for trying to be generous with its water.) Whether a stream loses or gains water from the land it is passing through depends on the level of the water table in the groundwater in the vicinity of the stream: if the water table near the stream is higher than the surface level of water in the stream, the stream gains from groundwater that trickles in. If the stream level is higher than the water table near the stream, the stream ‘loses’ (gives) water to the surrounding land.

Another observation about how a river behaves comes from looking at the material a stream is carrying, material it has cut, ground or otherwise eroded from its mountains, and realize that a river is both a creative and destructive force creating the landscape like a sculptor. Some sculptor – maybe Michelangelo? – said that his task was to remove the excess stone from a block of marble to reveal the beautiful figure within; so does the river create our magnificent vistas of mountains, couloirs, bowls  and valleys by cutting into and moving stone.

This reductively creative, creatively destructive process is enhanced in our river basin by the fact that most of the river’s water supply comes from a winter snowpack that melts out quickly over a couple months in what passes for spring in the mountains, and most of the river’s water goes ripping and tearing down the mountains, far too fast for more than a fraction of it to sink in as groundwater. But what does sink in is important to the river after that fast runoff; the groundwater moves at a leisurely pace through the ground – ranging from days and weeks to as much as a century – making its way down to the low places where the surface streams flow, and arriving in the post-runoff time, late summer and fall, when the stream needs the gain. The US Geological Survey has determined, through sophisticated studies of isotopes, that roughly half of the water in the Colorado River below its steeper tributaries entered the river as groundwater.

When the downhill slope gentles, even surface flows slow and the streams begin to drop the debris they have torn out and are carrying, and they move that debris around – or move around the debris themselves: so doing, they create meadows and floodplains through which they loop and meander, generating a lot of hyporheic exchange. Much of this exchange may be only into immediate riparian areas; but when streams roll into their own created floodplains, they spreads their excess bounty more broadly, raising a water table that might nurture grassy meadows, cottonwood forests – or lots of agricultural land. A good runoff makes a stream’s floodplains live up to their name, with shallow floods spreading new layers of silt and nutrients over them.

In trying to ‘think like a river,’ we do have to think about land-based life too, and the relationship of land-based life to water – which of course is existential: without water, there is no life as we know it on the planet. And land-based life depends absolutely on freshwater, which – remember from the last post here – is less than one percent of the water on the planet. And two-thirds of that modest percent is bound up in the ice sheets on Greenland and Antarctica.

All the life on the planet depends on access to the remaining tiny fraction of freshwater – which, by the time it has accumulated in streams and rivers is on its way back to the salty seas, despite their efforts to slow the process by meandering and offering their waters in hyporheic exchanges. More freshwater will come – or at least it always has – as the sun distills it again from the salty seas and precipitates it over the land, but still…. All that freshwater, essential to life, just running off to the seas where it disappears into the salt water, freshwater’s equivalent of dying….

If one wanted to let the imagination fly like an untethered kite for a moment – land-based life itself might be described as a freshwater strategy for confounding gravity’s pull back into the ocean. We – all of us, plants, animals, fungi, bacteria – are made up of highly specialized little vessels whose chief component when we are alive, is water. This is true of aquatic life that stays in the water, but it is also true of the rest of the planet’s life project that came out of the water to live on the land, a diversity of stacks and arrays and mobile units of tiny specialized cells full of a mix of minerals and gases dissolved in water. The watery cells that arrange themselves as molecular bucket brigades in trees lift water as much as three hundred feet into the atmosphere, against gravity, profligately venting most of that water back into the atmosphere to maintain that upward flow. We animals carry water everywhere, against gravity, far from the rivers. In this flight of imagination, humans, around 70 percent water, could be described as water that stood up to look around and think and dream.

Reeling that kite in – land-based life does interact with surface freshwater in many ways, some of which facilitate water’s willingness to carry out hyporheic exchanges with the land and the water-using organisms on the land, and some of which work against such exchanges. Beavers work to slow the flow of water through the land, pooling it up in ways that slow but don’t stop the flow, and so doing, nurture wetlands and wet-meadow ecosystems. And we humans move water out back out onto the land to irrigate it, again and again with the same water in the arid lands, using it to grow life that would never grow there at all unassisted.

We are also guilty of occasionally conspiring with the vagaries of nature to destroy the hyporheic exchange between streams and the land they run through, as when we unconsciously overgraze a wet meadow in a dry year – then a summer afternoon storm drops an inch or two of cloudburst rain on the meadow, and a raging torrent rushes down through the vulnerable sun-baked meadow, creating in an hour or so a gully that deepens in subsequent years, and draws down the water table of the former meadow, causing an ecosystemic change from a wetland ecology to a dryland ecology. Or a dam is built across the river, drowning the aquatic and riparian ecosystems above the dam and altering the ecosystems below the dam. Some of these kinds of changes are unfortunate; others are just unavoidable as we try consciously to make the planet more ‘fitting’ for human survival in ever-increasing numbers.

There are two further observations about these processes that seem almost confoundingly contradictory: the slower the flow, the more the stream or river gets to interact with the land. But at the same time, the more the water is spread out in those interactions, the more vulnerable the water is to the sun’s power. Among ourselves we say ‘use it or lose it.’ But in the bigger picture, it is ‘use it and lose it’ through increased evaporation and transpiration, as we ‘spread it out to dry.’

So given all of that – what can we say about ‘thinking like a river’ today, as we start planning for the operation and maintenance of our Colorado River in the hotter and probably drier Anthropocene? Given that it is only two-thirds the river we thought it was a century ago when we started to ‘develop’ it?

The most obvious thing from observing the river at its own work is to do what can be done to ‘slow the flow’ of water back to the sea – but to do it in ways that don’t just ‘spread it out to dry’ under the sun whose power is enhanced by our atmospheric changes.

One way to do this is to get more of the water underground but retrievable. Back in the 1930s, there was discussion about how best to bring the on-again off-again firehose of the Colorado River mainstem under a measure of control. The Bureau of Reclamation and the Army Corps of Engineers wanted big bold mainstem dams, like Hoover’s dam (already under construction), but the brand-new Soil Conservation Service favored a lot of small reservoirs and erosion-restoration projects up in the headwaters of the western rivers, followed by better farming, logging and mining methods. The idea was to raise water tables and increase the quantity of groundwater making its slow way downhill underground and out of the sun, before joining the river in its hyporheic games.

We know who won that discussion. But today, there is a growing movement to restore degraded landscapes by repairing gullied valleys and raising water tables, getting more water underground and out of the increasingly brutal sun. City utilities are cautiously exploring aquifer recharge, where over-pumping hasn’t already collapsed the aquifers. And we are moving toward consent about the fact that bypassing Glen Canyon Dam would increase the amount of water available for use by a third to half a million acre-feet, with no realistic loss of storage (put it all in Mead Reservoir). Had we given fewer resources to the Bureau of Reclamation and more to the Soil Conservation Service in the ‘30s, we would probably have more water in the river today.

I am not one of those who laments the fact that ‘the Colorado River no longer flows to the ocean,’ and don’t find that fact inconsistent with ‘thinking like a river.’ The amount of active freshwater on the planet is so relatively miniscule in the big picture that I think it would be just fine if land-based life figured out ways to put all of it to work on the care and maintenance of land-based life. That will of course never happen with a vast watershed like the Mississippi – although, given the dead zone its runoff is creating in the Gulf of Mexico, it might be better if it was all used up before New Orleans. I do realize that the lack of Colorado River water flowing into the Gulf of California has impacts on sea life there, but everything seems to involve choices, and in this one, I am inclined by nature to come down on the side of land-based life….

I think it would be nice if we could dedicate one percent of the river’s water to restoration of the beautiful old Colorado River delta – but it would be even better if we could figure out how to make the vast ‘desert delta’ we have created instead (Phoenix on the east through all the Lower Colorado ag lands to Los Angeles on the west) something we could love rather than dislike so much as we seem to…. Can we not build beautiful cities, desert ‘arcologies’ that we’d like to live in rather than ‘auto-urbs’ under a carbon-gas smog spreading out like a cow pooping on a flat rock? Or agricultural lands that aren’t rural industrial slums plagued by inequity?

Thinking like a river – water driven back to sea level by gravity (‘It’s the law!’) but doing what it can to slow its flow in places where it can give water back to the land as well as carry water off the land…. The water has systematic processes going on that we can participate in – have to, being water vessels ourselves needing constant replenishment. We’ve presumed, both consciously and unconsciously, to take charge of those systems along with a lot of other planetary systems; that’s what the Anthropocene Epoch is, and either we rise to the challenges there we’ve imposed on ourselves, or we will preside over our own slow and tedious unraveling. And maybe the first big challenge is slowing our own flow enough to begin to really think through the systems we’ve often just overrun in enthusiastic arrogance.