Recent fires and high temperatures across the West may have water users wondering what rising temperatures and sustained drought conditions might mean for Colorado water users. While only time will tell, it’s relevant to note that the summer of 2020 was one of the hottest and driest on record. The month of August was one of the top ten warmest Augusts on record according to the National Oceanic and Atmospheric Administration’s “August Climate Summary,” with 26 days above 90 degrees Fahrenheit and 17 days above 95 degrees! Denver received only 0.35 inches of precipitation in August, which is 1.34 inches below normal, and there were only 5 days total during the month with measurable rainfall at all.
What does this mean for Colorado water users? Changes in temperature and precipitation can impact snowpack, length of crop seasons and quantities produced, wildfires, and pests, just for starters. According to the US EPA, snowpack in the western United States has been decreasing since the 50’s, and the amount of snowpack measured in April at Colorado sites specifically has declined by 20-60%, on average. Diminishing snowpack can mean less spring/summer runoff, which typically provides much of the water needed by agricultural and municipal water users. Earlier runoff can mean changes in the priority system relied upon by Colorado water users, as many decrees for reservoirs (typically relied on to capture spring runoff for later summer use) have limitations on when such storage can start and when it must stop. Rising temperatures can also increase evaporation from soil, crops, and storage reservoirs, meaning more water is lost to the air than usual. Soils may become drier as evaporation rates increase, which can mean they retain more water when there IS precipitation so that less water is ultimately flowing into the state’s stream systems. Changes to Colorado snowmelt, rainfall, and temperature patterns may also impact Colorado’s farms and ranches. Increased evaporation can increase irrigation demands and mean that some farms change to dry land farming, which typically decreases crop yields.
Interestingly, the Colorado River Research Group encourages Colorado water users to consider our increase in drier years not as just “drought,” which implies that it is temporary and resolvable, but as “aridification,” meaning Colorado water users should expect that the drier, warmer conditions experienced by Colorado in recent decades will continue, and plan and adapt accordingly. This may mean securing secondary/backup water supplies, growing different crops, or installing more efficient diversion, delivery, and/or irrigation systems.
Lyons Gaddis has helped water users of all types plan for drought and other changes in water availability and type of use, and our water team is available to answer any questions you may have about this topic.