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For public water service providers, developers, agriculture, industry—truly anyone responsible for managing a water supply for an individual property or an entire city, county, or region—now is the time to redouble planning for a drier future.
As you look into 2022 and beyond, it is difficult to overstate the importance of planning ahead when it comes to water supply management in such an uncertain future.
While the historic severity of this past summer’s drought has alleviated with recent winter rain and snow in the early ’21-’22 winter season, water managers continue to plan on acutely challenging conditions to persist through 2022. Drought conditions remain in place throughout the entire region as of December 9. Between the long-term regional aridification trend and La Niña currently projected to continue through the winter, we expect another underwhelming snowpack in 2022. When springtime comes, leaky streambeds and severely parched soils mean that a lower proportion of runoff will travel to reservoirs and headgates than would under more normal conditions. In a word, the overall western drought remains, and looks like it will persist.
Image Source: US Drought Monitor
In 2021, Colorado’s Western Slope experienced the second driest year on record for the Colorado River Basin, just behind the 2002 water year, with stream flows a mere 31% of average. It was also California’s second driest on record in terms of statewide runoff. The National Oceanic and Atmospheric Administration (NOAA) reports that for the six states of the U.S. Southwest (Arizona, California, Colorado, Nevada, New Mexico, and Utah), January 2020 through August 2021 had the lowest total precipitation since recorded observations began in 1895.
Far from an anomaly, these bleak figures merely punctuate a long-term condition of chronic drought that has prevailed across the region for two decades, the overall severity of which exceeds any in the period of recorded climate observations beginning around 1900. Not coincidentally, Lake Powell and Lake Mead continue the drop to the lowest elevations since each reservoir first began filling. The year 2000 was the last time either was even close to full. No one can say for certain how long these conditions will continue to persist, but scientific reconstructions of the Southwest’s climate over the past 1,200 years suggest that observed records of climate over the past century do not represent a reliable planning baseline.
In California, December 1, 2021 marked the earliest date that California has announced a 0% allocation for water delivery from the State Water Project, except for health and safety purposes, until California “has a clearer picture of the hydrologic and reservoir conditions going into the spring”. The State Water Resources Control Board (SWRCB) has been grappling with efforts to curtail major water use in the California Delta in 2021, and continues interactions with water users to plan for potential curtailments in 2022.
As we reported in our August 24, 2021 Alert, the SWRCB approved an emergency curtailment and reporting regulation for the Delta watershed which became effective on August 19, 2021. This administrative action was based on a Water Unavailability Methodology, and curtailment and reporting orders were issued on August 20, 2021 for one of the first times. The SWRCB directed its staff to engage with stakeholders to identify and explore other possible approaches, and a workshop on this topic will be held on December 15, 2021.
Image Source: US Drought Monitor
Image Source: US Drought Monitor
The period of ongoing regional aridification beginning in 2000 is an anomaly in the 120 years of observed climate records, but this short timeframe likely paints an incomplete picture of just how much long-term variability should be expected to naturally occur in the region’s climate.
A 2020 “State of the Science” report sponsored by lead water agencies across the seven Colorado River Basin states took stock of current scientific understanding of climate and hydrology in the region. Chapter 10 of that report surveys the topic of “paleohydrology,” or the scientific discipline of reconstructing hydrologic events and processes prior to the instrumental (gaged) record, typically using environmental proxies such as tree rings. The report authors’ key points include:
Similarly, a 2020 study published by a research team out of Columbia University’s Lamont–Doherty Earth Observatory, which relied on tree ring samples as a proxy for soil moisture, showed that four megadroughts lasting 30-40 years occurred across the region between the years 800 – 1600, and concluded that the current Southwestern drought is the driest 20 year period since the last megadrought in the late 1500s, and the second-driest since the 800s.
In sum, the records of the past 100 years likely do not provide a reliable picture of the range of natural variability to expect in this region’s climate. Planning based on the arid conditions that have prevailed across the region for the past 20 years may well be required for decades to come.
As 2022 approaches, a number of strategies may be considered for adapting to persistent drought, as noted below:
The success of any combination of the above strategies may depend on the local severity and duration of a drought event, specific water supply sources, seniority of water rights, drought storage reserves, and drought mitigation and response measures in place to address potential shortages.
As you look into 2022 and beyond, it is difficult to overstate the importance of planning ahead when it comes to water supply management in such an uncertain future. Somach Simmons & Dunn is experienced in strategizing and executing drought response endeavors to assess water supply and work on adaptive solutions with water users.
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