New Irrigation Strategies in a Rapidly Changing Environment
By Thomas Skernivitz, Senior Editor, American Fruit Grower and American Vegetable Grower
Researchers seeking a geographic poster child for climate change in the U.S. need not break a sweat — record-high temperatures or not. Their search can easily settle upon the Pacific Northwest (PNW).
Tucked in the corners of two countries, the region has spent at least the last decade enduring a climatic home-field disadvantage based on extreme weather events.
The 2015 growing season in Washington state was one of the driest on record due to early, rapid snow melt. Temperatures during that season’s water year — Oct. 1, 2014, through Sept. 30, 2015 — ranged well above average.
In 2021, despite a probability of near zero, an unprecedented “heat dome” struck the PNW between June 25 and July 7. All-time highs were set in British Columbia (121° F) and Washington (120° F) and tied in Oregon (119° F).
Nine months later, Washington went full 180, experiencing its third-coldest and 10th-wettest April in 128 years. The entire meteorological spring (March through May) was the fourth-coldest in much of Puget Sound over 130 years of records.
As growers in the PNW are increasingly learning, if not fearing, when you’re hot, you’re hot; when you’re not, you’re not. Not a bad motto for a climate change poster.
How is this affecting growers in Washington, Oregon, Idaho, and British Columbia? More importantly, how will it affect their children and grandchildren the rest of this century?
Washington State University (WSU) has paid particular attention to the topic. Jennifer Adam, the Berry Distinguished Professor of Civil and Environmental Engineering at the school, has taken advantage of state-of-the-art science and modeling to provide a clearer understanding of the Columbia River Basin while projecting its water future in eastern Washington.
Plenty to Think About
The PNW’s vulnerability to climate change worries Adam on two fronts. Considering she is a hydroclimatologist, her concerns hold, well, a fair amount of water. One vulnerability is wildfire, which is a topic for another day. The other, even more pressing, she says, is the loss of snowpack.
“Those are the two big ones as far as what that I’ve seen from living here in Washington for the last 22 years but also as an academic,” Adam says. “We desperately need our snowpack. In many watersheds, it’s actually our only way of storing water. We don’t have major reservoirs throughout all of these watersheds, nor do we necessarily want to have major reservoirs throughout. This is where we really need to think about the snowpack.”
Enter the latest edition of the Columbia River Basin Long-Term Water Supply and Demand Forecast, of which Adam is the Lead Researcher and Project Manager. Released every five years (Aug. 1 most recently), the report helps to improve understanding of where additional water supply is most critically needed now and in the future. Snowpack, snowmelt, and the watersheds that they feed will play significant roles in the Columbia Basin over the next two decades and beyond, according to the 2021 Forecast.
“The difference between climate and weather has to do with large spatial scales and long temporal scales,” Adam says. With regard to time, “we’re looking mostly about 20 years into the future, but we’re also going to look about 50 years into the future.” Spatially, “instead of looking at your farm or your plot, we’re looking at the Columbia Basin as a whole and then the watersheds within that.”
The Columbia River, which winds through eastern Washington, measures 1,243 miles overall and boasts the greatest flow of any North American river entering the Pacific Ocean. Its drainage basin, roughly the size of France, includes 34 watersheds, or Water Resource Inventory Areas (WRIAs), in eastern Washington.
Agriculturally, the Columbia Basin Project, an irrigation development in east central Washington, generates an annual crop value of $2.66 billion while providing water to more than 10,000 farms, according to the Columbia Basin Development League. Primary crops include hay, potatoes, corn, wheat, beans, orchard fruits, grapes, herbs, onions, and grass seed.
“Managing water supplies and meeting the needs of the environment, agriculture, industry and the growing communities of eastern Washington will only grow more challenging in the decades ahead,” Tom Tebb, Director of the Washington Dept. of Ecology’s Office of Columbia River, reports. “In our office, we are moving forward a number of initiatives to meet those needs, and this report is an important tool to keep our work on track.”
‘Snow Drought’
The 284-page report — prepared by the Washington Dept. of Ecology, State of Washington Water Research Center, WSU, the University of Utah, and Aspect Consulting — concludes by suggesting that eastern Washington is vulnerable to:
Water supplies increasing earlier in the spring/winter and decreasing later in the summer/fall
More extremes in water supply from year to year
Declining low flows, affecting important fish species
Areas of diminishing groundwater supplies
Watersheds with increases in out-of-stream demands
The first of those bullet points speaks to the snowpack dilemma, which is exacerbated by one of the telltale signs of climate change, higher temperatures.
With the snow disappearing earlier, the historically dry months of June through October will experience a decrease in water availability.
As climate change pushes average temperatures higher across the PNW, the region will see more rain and less snow in the mountains such as the Cascades, earlier snow melt, and shifts in river flows and water supplies. With the snow disappearing earlier, the historically dry months of June through October will experience a decrease in water availability.
In other words, a repeat of the aforementioned drought of 2015.
“I hope you all remember what happened in 2015,” Adam says. “Winter temperature really matters, and we learned that in 2015. Warm winter temperatures and average winter precipitation caused drastic drought because there wasn’t a snowpack or very little snowpack. That’s when we started coining the term ‘snow drought’ because the winter precipitation was normal. It was all related to temperature.”
“Around 2080 we’re going to see 2015 being a normal condition,” she says. “Well, that’s a long time from now. The good news is that we have time to adapt. We have some time to do something about that.”
One of the report’s take-home projections, according to Adam, is that 2015 will likely represent average conditions at the end of this century.
The report also projects slight declines in agricultural irrigation water demand across many areas of eastern Washington, as farmers plant their crops earlier in the season, which makes use of more rain. However, growing populations and changes in the mix of agricultural crops will likely result in greater demands for water. And the tension between keeping river and stream flows high enough to support fish and the demands on hydropower to power electric vehicles, data centers, and other uses will only grow more acute, according to the report.
“You overlay all of these different issues, and you can identify areas where there are going to be critical problems, which helps the Dept. of Ecology know how to focus their resources,” Adam says.
Aspect Consulting owns the rights to these images. It allows non-exclusive rights to Meister Media Worldwide to use these images for this specific story only, both in print and online (website, newsletter, social media). Please attribute the images to Aspect Consulting.
Photos on pages 2, 4, and 5 courtesy of Aspect Consulting.
Cover Photo: The Cascade Range and Columbia river as seen from Wenatchee, WA. (Credit: Jaskaran Kooner)
