by George Sibley
Our fearless CC leader has requested that for this issue we address “Colorado Facts.” So, since it’s what I seem to be spending most of my time on these days, I will try to entertain you with a Water Fact, and the mental turbulence that can be set off in the human mind – mine, anyway – by a single fact gone wild, running loose. Or no, not “gone wild” – instead, a fact that has not yet been brought in from the wild, an elusive Sasquatch of a fact hanging out on the edge of a civilization that doesn’t yet know how to live with it.
The Colorado Water Fact currently driving me crazy: Quite a lot more water falls (mostly as snow) on our mountains than makes it into the rivers and streams that begin in or near Central Colorado – the Arkansas, Rio Grande, North and South Platte, and Colorado Rivers. The water in those rivers is important to millions of people in 19 states in the American Southwest and Lower Midwest, and plays a huge role in arid-West agriculture.
Together these Colorado-born rivers carry on average roughly 10 million acre-feet of water a year out of our mountains. Coloradans get to consume about a third of that water; the rest we are committed by nine interstate compacts to send on downstream to 18 other states.
Meteorological analysis, however, indicates that considerably more than 10 million acre-feet of water falls every year on these Central Colorado mountains – maybe as much as 40 million acre-feet.
Given the population projections for the coming decades, including a possible doubling of Colorado’s population by mid-century, and the extent to which our water resources already seem to be used to the max, shouldn’t we be studying where the other 10-30 million acre-feet of “lost water” are going?
Well actually, we are; the U.S. Geological Survey is studying it, and a fair number of graduate theses and professorial papers are going to come out of other parallel research, some funded by organizations like the National Oceanic and Atmospheric Administration (NOAA). At this point we know that a lot of water falls on the forested slopes of the Colorado Rockies, but only a large fraction of it emerges out into the watersheds of the West. The rest is, as it were, lost in the woods.
Obviously a lot of that water is used by the trees themselves; even the relatively parsimonious conifers of the montane and subalpine forests use a lot of water; the lovely aspen use even more. And don’t even ask what the riparian willow thickets and the big old cottonwoods in the lower reaches drink. The trees don’t just use water for their own sustenance and growth; they, along with all other plants, have built-in air-conditioning systems that evaporate quite a lot of water to regulate their temperature – a process called evapotranspiration.
But there is another way in which water is lost between the time that it falls as snow on the mountains and the time that it emerges from the mountain forests in streams and rivers: sublimation – a process that is terribly frustrating to anyone who sees virtue in utility and efficiency. This is a process by which water in its solid state (snow or ice) becomes water vapor directly without going through its liquid state first. The heavens, in other words, shed their bounty of water-as-snow on the earth – then take away a portion of it before it can bless any of earth’s living things. How much? Some research indicates that sublimation might suck up as much as a third of that lost water, especially in the drier years when the water is most needed.
How does sublimation happen? It happens when snow gets blown around a lot, which it does in the high alpine “rock-and-ice” zone (above 10-11,000 feet in Central Colorado). But most sublimation is due to the sun – even when air temperatures are well below freezing. There is some sublimation from the snowpack itself, but not so much, because most of the shortwave incoming radiation from the sun glances off the glistening white snowpack through the “albedo” effect. But snow that falls on dark surfaces, like conifer tree branches or large rocks, or the roof of the building outside my window here – leaving some of the dark surface exposed – gets literally cooked off of those surfaces as the dark material absorbs the shortwave radiation as long-wave heat radiation. And I can see it – I have to sit and watch it. Water vapor rising off the edge of the snow on the roof outside the window when the air temperature is 10 below zero – potential water, just disappearing back into the atmosphere. Aaaghh!
Is there nothing that the tinkering species can do about this – something that would not, as our tinkering often does, make a bad situation worse in some unanticipated way?
We know from bitter experience that removing all the trees from the slopes is a very bad solution; it releases more water down the mountains, to be sure, but it all comes at once in a ripping muddy flood.
So we obviously can’t take all the trees off the mountains to get the water they use, but do we need all of those trees? Could we do some careful thinning in the forests above 8,000 feet that get the snow – say one tree in every three or four or so, to reduce the canopy that catches and sublimates snow, but not so many as to make the snowpack vulnerable to the wind?
Again, my questions have at least a partial answer. Since relatively early in the 20th century, forest researchers have been conducting thinning experiments, some directly focused on increased water production. All of those experiments conclude that yes, it is possible to increase the water yield from forested land, but maybe not by very much. Removing around 20 percent of the canopy might increase the water yield three to six percent – but that result is ambiguous since the margin of error in measuring water flows is still around five percent. Would removing another 5 to 10 percent of the canopy increase that yield enough to matter? Or, would that just open the snowpack up to the wind, thereby negating the gain from reduced canopy branch loss? And are different water yields possible from different types of forest cover? Radical canopy reductions in ponderosa pine to create pine-and-grass savannahs, for example, have resulted in intermittent streams becoming steady flows.
Finally, a big logistical question: if population growth combined with climate-change depletions forces us to try for a 5 to 10 percent increase through reducing sublimation, who is going to do the work of thinning millions of acres of mountain forest land (outside of wilderness areas and national parks)? And then maintain the reduced cover? Could it be done without an unwanted, extensive new road network in currently roadless places?
It should be noted here that this kind of thinning effort might also be desirable for general forest health under projected climate changes, above and beyond water yield. On one of the vast mountainsides of reddish-brown beetle kill in Grand County, there is an anomalous patch of green – a Forest Service experiment in canopy reduction to increase water yield.
It is, however, impossible to imagine taking on a scaled-up challenge like recapturing a few hundred thousand acre-feet of that lost water and also improving forest health under current funding for environmentally intelligent work. It goes on a list with other projects, like The Nature Conservancy’s wet-meadows project, river restorations, stream reconstruction projects to fit the stream channels to reduced flows, and a host of others; all of these are labor-intensive projects that would require an American army, dedicated not to foreign petrowars, but to something like President Carter’s “moral equivalent of war” – a careful struggle to keep the planet livable for humans. We might begin to nick into the challenge if a program of universal national service (no exceptions, no buyouts for the wealthy kids) were implemented for high school graduates (dropouts too) to truly tackle the infrastructure for a great 21st -century nation-state.
But don’t expect anything to happen on that front for a while, if ever. You do see, though, how one little fact can work its way into the mind, confluent with other irritant facts, and the next thing you know, you’re needing to change the world.
Meanwhile, here is another Colorado Fact. For the past 15 years or so, the Russian Orthodox congregations along the Front Range have been holding an annual “Blessing of the Waters” at the summit of Monarch Pass every January. For those of us who worry too much about water we don’t have, it’s an invitation to come celebrate the water we do have, still in its solid state (sublimating away of course). This year, the Blessing of the Waters will be held on top of Monarch on Thursday, Jan. 8, at 11 a.m.. That is, unless the pass is closed by weather, in which case the Blessing will happen on the Arkansas River somewhere down in Salida. Father Karbo and the R.O. congregations have no problem with pagans like me attending. See you there.
George Sibley watches water sublimate in Gunnison.
