The Deschutes River Conservancy is hosting a series of educational seminars on local water issues called Raise the Deschutes. You can watch recordings of presentations and get notifications of upcoming seminars by visiting their site. Earlier this week the DRC hosted a seminar with a speaker from the Oregon Water Resources Department titled “Groundwater in Central Oregon: How is it all Connected?”. If you have not spent years reading the scientific reports, attending the meetings, and otherwise becoming a water nerd, I encourage you to watch the recording. It was a good, high level, overview of the geology and hydrology of the Deschutes Aquifer. That being said, I do have some criticisms.
As their name implies, OWRD views water as a “resource” to be consumed, primarily by agriculture, industry, municipal, and domestic uses. As I have pointed out many times in the past, fish, wildlife, the environment, and human recreation are not significant elements in OWRD’s decisions to allocate water, if considered at all. This was clear in the presentation and the answers to subsequent questions.
First, here’s an extremely truncated overview of local hydrogeology. The Deschutes River emanates from an aquifer created by snow falling in the Cascades. That snow is the most abundant reservoir of water possible. Due to historically long, cold winters with ample snowfall followed by cool springs, snow slowly melted, providing a steady stream of water throughout the summer and fall that seeps into the aquifer through young, porous lava.
Some of that water quickly reemerges in high elevation springs which create rivers like the Deschutes and creeks like Tumalo and Bridge, the source of most of the City of Bend’s drinking water. The rest of the aquifer flows downhill underground until it encounters an impermeable layer and emerges in springs, rivers, and creeks near Lake Billy Chinook. Unknown to many, approximately 700 cfs of warm water emerges in the bottom of Lake Billy Chinook at the edge of the Confederated Tribes of Warm Springs reservation.
The slow, steady release of water from melting snow gave the Deschutes unusually stable flows. Unlike most other rivers, this is not a “flashy” system: one with high flows in the spring that dwindle through the summer and fall. The Deschutes’ stable flows provide amazing habitat for fish and wildlife.
With that background, here’s my first criticism of the OWRD presentation. The claim was made that global warming will not make an impact on water availability in the Deschutes Aquifer. Global warming will not make an appreciable impact on the amount of precipitation the Cascades receives, if anything it will be greater, but it will come as rain rather than snow. The recent drought is part of normal weather variability. (Huh? The worst drought in 1,200 years is part of normal weather variability?) So, what’s to worry about? (This is not the first presentation I have heard from OWRD that had an element of global warming denialism in it.)
Even if we make the rather huge assumption that we will see more precipitation in the future (see this post for an alternate view), the form of that precipitation makes a significant difference in the availability and timing of surface water above Lake Billy Chinook. If we value fish, wildlife, and human recreation a reduced snowpack and faster melting will have profound consequences.
In 2019 the US Forest Service released a report titled “Climate Change Vulnerability and Adaptation in South-Central Oregon” which states exactly this. I encourage you to read the abstract, it says all you need to know. Here’s an excerpt:
The vulnerability assessment shows that the effects of climate change on hydrology in south-central Oregon will be highly significant. Decreased snowpack and earlier snowmelt will shift the timing and magnitude of streamflow; peak flows will be higher, and summer low flows will be lower. Projected changes in climate and hydrology will have far-reaching effects on aquatic and terrestrial ecosystems, especially as frequency of extreme climate events (drought, low snowpack) and ecological disturbances (flooding, wildfire, insect outbreaks) increase.
The report states that high elevation streams, like Bridge Creek will likely have very low flows in the summer, precisely the time when the City of Bend uses the most water. This change in timing of flows will also impact irrigators. In the past, reservoirs like Wickiup, the primary source of water for North Unit Irrigation District, would not only fill, but would be replenished all summer long by flows from the Deschutes River and other high elevation sources, leaving an ample supply of water through the winter. This is less likely to be the case as the planet heats up, even if total local precipitation increases. Less stable flows also present the possibility of overflow and flooding events.
Of course, if your mission is to allocate groundwater for pumping then precipitation falling as rain may not be a significant issue. Rain or snow will percolate into the aquifer and be available at lower elevations for pumping, although the variability of the depth of available groundwater will increase. It’s all about your perspective. I guess all we have to do is drill deeper wells.
My second criticism has to do with the dismissal of exempt wells as an area of concern. We all know that irrigators are the dominant users of water in Central Oregon. Industrial, municipal, and domestic use is a tiny fraction of total consumption. Nevertheless, local municipal water systems are metered and water use is monitored with associated fees. The OWRD representative stated that it was not worth the effort to do the same for exempt wells, even though they use far more water on a per household basis. If local municipal water users have their water use metered, why not exempt well owners? Why shouldn’t exempt well owners pay a fee based on water usage? How can we manage something that is not measured? (Full disclosure, I have an exempt well.)
To finish this thought, irrigators should also be charged for water usage. Currently, they pay a fee to their irrigation district to manage the canals, but there is no charge for the water itself. The fee could be based on a sliding scale so that water used in an economically productive manner would be very low cost. Given that most irrigators are “hobby farmers” this would be a great way to reallocate water towards true beneficial use. (The US Department of Agriculture states that only 11% of irrigators in Deschutes County have a economically viable farm, the rest are hobbyists. I support anyone’s right to pursue their hobby, but shouldn’t they pay for it?)
A final comment: some data was presented that reflected statewide statistics. I question the use of these in a presentation intended to reflect conditions in the Deschutes Basin. I think its better to be quiet than potentially misleading.