The Department of Water Resources has just announced that they are increasing the State Water Project allocations to 15%. Given the huge problems last year with watershed runoff forecasts, DWR is taking a huge risk of not meeting environmental water needs later in the year.
In November 2021, nine scientists from leading California water research institutions wrote:
Delivering as much water as practicable to urban and agricultural users leaves no room to adjust for errors in forecasting or unanticipated worsening of conditions. Yet, as 2021 and previous drought years show, forecasting, modeling, and operational errors are the norm – not the exception – during droughts. These errors inevitably lead to increased harm to the environment and the likelihood of errors is increasing with a changing climate.
For example, in 2021 the projects used optimistic runoff and climate forecasts that over-estimated their ability to meet downstream temperature standards. These forecasting errors were compounded by unanticipated high diversions and in-stream losses, both above and within the Delta. The higher downstream water uses required larger reservoir releases to maintain Delta water quality and made managing water temperatures even more difficult.Null et. al. Managing Water Stored for the Environment During Drought.
In June of 2021, we asked the State Water Resources Control Board to require the Department of Water Resources and the Bureau of Reclamation to provide a report on the reasons for the major errors in runoff forecasting, and to hold a workshop on runoff forecasts. DWR has since revised their 2021 snow runoff forecasting method, but did not provide a report. The Water Board did not hold a workshop.
DWR’s press release states, “DWR continues to plan for climate uncertainty by implementing emerging and proventechnologies to improve forecasts of precipitation, seasonal snowpack and runoff.” But DWR’s new runoff forecasting method is untested and has not been provided for independent experts to examine. Nor to my knowledge has there been independent peer review. And the Dixie Fire is likely to alter watershed hydrology. This is a Don’t Look Up moment for the Sacramento-San Joaquin Delta.
California Department of Water Resources, 2022. December Storms Allow for Modest Increase in Planned State Water Project Deliveries, Press release. January 20, 2022.
Des Jardins, D. 2021. On DWR’s water supply models and drought risks. California Water Research blog, September 14, 2021.
Des Jardins, D. 2021. TUCP: California Water Research asks Water Board to require report on 2021 runoff forecast errors. California Water Research blog, June 5, 2021.
Des Jardins, D. 2021. DWR Chief Engineer warned of climate change draining northern California reservoirs. California Water Research blog, May 10, 2021.
Lund, J. 2022. How dry will 2022 be? California Waterblog, November 28, 2021.
Null, S. Mount, J., Gray, B., Dettinger, M., Dybala, K., Sencan, G. Sturrock, A., Thompson, B., Zeff, HB. 2021. Managing Water Stored for the Environment During Drought. California WaterBlog, November 7, 2021.
Obegi, D. 2021. California Doesn’t Have a Plan for Drought. Natural Resources Defense Council expert blog, May 19, 2021.