A team out of Wyoming, including my Colorado River Research Group colleague Kristiana Hansen, has a new paper that reminds us that we need to be careful about how we thinking about conserving water that is being “wasted.”
Their case study is an area on the New Fork in Wyoming, a tributary of the Green, which is a tributary of the Colorado, where producers use flood irrigation on timothy grass to grow livestock forage.
Flood irrigation is often seen as “wasteful.” One approach is to install “more efficient” irrigation technology. But – and this is one of my repetitive talking points with students in the graduate water policy course I teach every fall – you need to flag the word “waste” when you see it in a water policy discussion and think carefully about how you’re using it.
That water is going somewhere, and doing something. You have to include this in your analysis. Maybe it’s really being “wasted”. But you may find that the place the water is going, and the thing that it’s doing, is valuable!
That’s what the Wyoming team found. Flood irrigation recharges the shallow aquifer – reducing the spring peak in the area’s streams, and slowly releasing that water back into those same streams in late summer. Which is crucial, in this case, for economically valuable fisheries – recreational brown trout fishing, to cite their analysis.
This is at the heart Bruce Lankford’s oddly named work on the “paracommons,” which has provided an enormously helpful analytical framework for my thinking about this stuff.
Cleaning up our urban sewage for reuse is super popular right now, and can in some cases be an enormously powerful water policy response to scarcity. But we’ve got to be mindful about where that “wasted” water is going and what positive benefits it is providing. Lots of inland urban cities in the southwestern United States treat their wastewater and return it to rivers, where it feeds ecosystems and downstream users.
We always have to consider the tradeoffs.
Thanks for bringing up this old subject. Waste is in the eye of the beholder. I am often thinking about how in the heck the Imperial Valley irrigators can keep irrigating with the super-salty Colorado water. I have seen some drip systems there-how do they manage to get the salt out of the root zone and continue to grow crops? No wonder so many farmers still do furrow irrigation, you have to over-irrigate to flush the root zone of sodium.
Regards contributions of canal and field seepage to groundwater return flow and river flow see “Surface Water and Groundwater Interactions in Acequia Systems of Northern New Mexico” (Carlos G. Ochoa, Steve J. Guldan, and Sam Fernald) Part 2, New Mexico State University Research Report 796 “Acequias of the Southwestern United States: Elements of Resilience in a Coupled Natural and Human System” (November 2020) https://pubs.nmsu.edu/acequias/index.html
Re: Alexander G. “Sam” Fernald: see also “Hydrologic, Riparian, and Agroecosystem Functions of Traditional Acequia Irrigation Systems” (Journal of Sustainable Agriculture, Vol. 30(2) 2007) https://wcrg.nmsu.edu/northern-nm-water-research/documents/hydrologic-riparian-and-agroecosystem-functions_fernald-et-al-2007.pdf
As an example of this, Salt Lake City leadership is promoting wastewater reuse currently, even though it would reduce inflows to Great Salt Lake. I learned recently that a coalition of environmentalists and outdoors enthusiasts in the late 1970s endorsed these sorts of alternatives (which also included diverting Bear River water, one of the main sources of water for GSL) as preferable to developing Colorado River water through the Central Utah Project. Great Salt Lake wasn’t a concern at the time. Not faulting them, just underscoring the point that it’s important to be circumspect.