USDA Outlook Forum discusses drought and water supply in Western agriculture
Arlington, Va. – During the U.S. Department of Agriculture’s (USDA) 99th Annual Agricultural Outlook Forum, held Feb. 23-24, U.S. Forest Service Research Hydrologist Charles Luce, National Drought Mitigation Center Geoscientist and Climatologist Brian Fuchs and Western States Water Council Executive Director Tony Willardson gave a presentation titled, “Drought, Water Supply and Western Agriculture.”
Background
USDA Economic Research Service (ERS) Research Agricultural Economist and Moderator Nicholas Potter noted in the last decade, the level of drought in Western states is approaching 60 to 70, even 80 percent of the land in these areas have been under some classification of at least severe drought.
“This matters for irrigated agriculture in the Western U.S., because a lot of water used for irrigation comes from surface water sources, which are affected by levels of drought,” he said.
In 2019, the ERS, in conjunction with the National Agriculture Statistics Service, conducted a survey of irrigation organizations across the U.S. He explained this was the first survey of its kind since 1978.
He noted, “Federal water projects and direct diversions from streams, lakes and ponds make up over half of the amount of water irrigation organizations get and then deliver to farmers. When we think about the impacts of drought on irrigated agriculture, it is substantial.”
Drought frequency
and severity
Luce explained hotter temperatures, with more consecutive dry days and reduced snowpack, are two sets of mechanisms affecting drought.
He noted the atmosphere can hold water, and it’s always hungry for water. This is referred to as vapor pressure deficit (VPD).
“Temperature-based methods are inherently flawed because the temperature state does not uniquely determine the evaporative reflux,” he said. “In fact, both the evaporative reflux and temperature are defined together by the supply water and energy, so what is fundamentally changing with climate change is the supply of energy and water.”
There are two important contexts in the conversation about irrigation – irrigated fields and the rest of the landscape.
Evapotranspiration is the process by which water is transferred from the land to the atmosphere by evaporation from the soil and other surfaces and by transpiration from plants. Luce mentioned from 1980 to 2018, evapotranspiration across the U.S. has been on a downward trend as both temperatures and the number of consecutive dry days increase.
In the Western, U.S., it is common for precipitation to occur in the winter and to have a dry, warm growing season. He noted mountains are a key feature of the irrigation story, but two nominal mechanisms impacting drought in the West are hotter temperatures and changes in snowpack.
Drought resiliency efforts
Fuchs noted the reach of the National Drought Mitigation Center services and activities has always been quite broad since the center was founded in 1995.
“We have this history of working on drought as a topic, but we come at it from multiple directions and monitoring is one to them,” he said. “With drought frequently impacting the U.S., drought-related Climate Services and partnerships are an essential part of our work.”
The U.S Drought Monitor (USDM) has continuously evolved from past efforts to monitor drought including from the earliest versions of the map.
“Instead of looking at streamflow, the Palmer Drought Index, ground water or soil moisture all by themselves, we take the best attributes of all of these different data sets and put them together into a single product,” said Fuchs. “Instead of using a single index, a hybrid model is used.”
The USDM map is an attempt to represent all of the different types of drought on one map, including meteorological drought, agricultural drought, hydrological drought, socioeconomic drought and ecological drought. Fuchs noted this is a challenge, but the USDM has been an important tool to trigger mitigation, action plans and relief programs.
“For the entire U.S., there have been periods in the 2000s where we experienced multi-year significant drought periods,” he said. “But then, we also see some periods in the mid- to late-2000s where drought wasn’t too big of an issue.”
He noted in 2013, almost 80 percent of the country had some level of dryness.
“We’re not only talking about problematic episodes for certain parts of the country, but what the USDM map is showing is everyone is vulnerable,” he said.
In closing, he shared U.S. drought magnitude and duration has impacted much of the Western U.S. at various points in time over the last several decades. Data trends are showing this region has already become drier.
Understanding the impact of drought in the region must encompass analyses of all types of drought, including ecological, agricultural, hydrological, meteorological and socioeconomic.
Utilizing paleoclimate data, some of the more modern droughts observed are not out of the realm of possibilities for the region, and building resiliency and adaption measures will be needed to sustain vital resources of the region and to lessen the impact of drought for everyone.
“If we continue down this road of the ‘status quo’ or ‘business as usual,’ we’re going to see more hardships and more people dealing with issues due to drought,” he said. “The worst time to deal with a drought is when one is in the middle of one. It will be important to plan and prepare ahead of time.”
Regional collaboration
Willardson shared the Western States Water Council is a state government entity, which serves as an advisory body to 18 Western governors on water issues. They provide states a collective voice, foster state to state and federal to state collaboration and work with the Western Governors’ Association and Western Federal Agency Support Team.
Their mission is to ensure the West has an adequate, secure and sustainable supply of water of suitable quality to meet its diverse economic and environmental needs now and in the future, he noted.
“Western states have primary authority and responsibility for the appropriation, allocation, development, conservation and protection of water resources,” he said. “Water in the West is an increasingly scarce and precious resource.”
He noted Lake Powell and Lake Mead are two of the largest reservoirs in the U.S., with 25 to 27 million-acre feet (af) of water, with several million af going to the Colorado River.
The Colorado River and tributaries supply water to 40 million people and provides $5 billion-a-year to the agriculture industry, but it’s now stressed by drought, he shared.
According to Willardson, the states missed a mid-August deadline to address U.S. Bureau of Reclamation’s (BuRec) call to propose ways to conserve two to four million af of water.
In January, Arizona, Nevada, New Mexico, Colorado, Utah and Wyoming sent a letter to BuRec, which operates the major dams in the river system, to outline an alternative to build on existing guidelines, deepen water cuts and factor in water lost through evaporation and transportation.
The modeling would result in about two million af of cuts in the Lower Basin, with smaller reductions in the Upper Basin. Mexico and California are factored into the equations, but neither have signed the letter. Although, California released a proposal last October to cut 400,000 af.
“Water must be recognized as a critical public policy priority given the importance of the resource to our public health, economy, food security, environment and Western way of life,” he said.
“One of the things we hope our work on water rights will do is to provide farmers and ranchers producing irrigation districts and others with information on their water rights, so they can understand how it fits into the larger context,” shared Willardson.
Brittany Gunn is the editor of the Wyoming Livestock Roundup. Send comments on this article to roundup@wylr.net.
