by Jay Lund

After three years of drought and two dry months, plus two wet weeks, into California’s “wet” season for 2023, California has become unsettlingly settled into this long drought.  Most cities have decreased their water use, some more than others.  Agricultural fallowing has been modest statewide, but large in the Sacramento Valley, with major economic effects in areas depending on rice-growing.  Impacts to native fish and forests have been accumulating, and are dire in some cases.

What is California’s water situation in early December 2022?

What are some drought lessons so far?

What are prospects and preparations for additional dry years?

Storage in Major Surface Reservoirs

Reservoir levels remain low, but within California they are slightly improved from last year at this time.  Nevertheless, there is little surface water reserve to be drawn down if this winter remains dry, and much of that would be needed for Delta outflows to keep the Delta freshish this coming summer.

The ongoing depletion of lower Colorado River water storage means that overall storage available to California is diminished (perhaps including any remaining California water “banked” in the Colorado River basin), and embroils California with increasingly dire Colorado River issues, especially for the Salton Sea.

The immense Colorado River reservoirs have been draining rapidly, about 3 million acre-ft in the last year, to supply about a third of water use in the lower basin and Mexico (about 9 maf). Continued drawdown in these reservoirs could jeopardize the ability to use some dam outlet structures this coming summer.

The good news is these low reservoir levels make flooding less likely this water year, so far at least.

Surface Storage as of October 31, 2022 (water year 2023):

Precipitation so far

It remains too soon to say much about precipitation for the 2023 water year.  After the first 2 months, precipitation is currently 85% of average for northern California.  So far, it has not been wet, but there is time for this to change, with the wettest months of the water year still ahead. The last week has put some water in this wet season, but the water year is still young.

Snowpack so far – Very early, but with the last week or so of storms, California is at 150% of average for this time of year.  An unusual time recently where snow is above average and total precipitation is a bit below average.

Drought damages so far

Just before Thanksgiving, a group led from UC Merced produced an insightful report on the impacts of this drought on agricultural water use, production, and economic performance (Medellin-Azuara et al. 2022).  The table below summarizes from this report, and adds results from the worst two years of the previous drought (from Howitt et al. 2014, 2015).

Condensed Summary of Recent Drought Impacts to Agriculture:

Note: *2014 and 2015 estimates were done using somewhat different methods and baselines, and not corrected for inflation, and so are only roughly comparable.

Some pretty interesting preliminary results stand out (highlighted in the table), which are discussed more in the original reports:

1. All four drought years were similarly dry overall, but 2015 was the worst.
2. There was a big and unusual shift of surface water supply reductions in 2022 to the Sacramento Valley from the Tulare basin, helping explain the large fallowing of rice lands in the Sacramento Valley in 2022.
3. Additional groundwater pumping due to drought seems to have diminished in the post-SGMA drought years, unless this difference stems from differences in estimation methods. (I’ll be hopeful for now.)
4. Net water shortages were more balanced across river basins in the 2021-22 drought years, shifting fallowing more to the Sacramento Valley from the Tulare basin.
5. Economic losses in terms of value added from crop and livestock production seem pretty similar across droughts, but job losses were a little larger recently.
6. These newer agricultural drought impact studies are more complete.

Some of these differences might be due to differences in methods and baselines, especially between the two droughts.  We’ll have to see how more detailed post-drought analyses come out.  It would be nice to see such regular assessments on ecological and rural community drought impacts.

The quantities of water shortages and land fallowing during these drought years is roughly what we should expect to see permanently with the implementation of SGMA. 

Prospects for another dry year

The likelihood of additional dry years is high enough to prepare for more drought.  Low reservoirs and declining groundwater make such preparations even more prudent.  DWR’s minimal initial State Water Project water allocations for the coming year are along this line.

DWR recently released an interesting survey of urban water shortage likelihoods for next year.  There was widespread expectation of an additional dry year, with quite a few agencies expecting cuts in their regular water sources.  However, of hundreds of sizable urban water suppliers, very few expected great difficulty in accommodating these water source reductions, having made preparations for alternative sources (from groundwater, purchases from farmers, additional water conservation, etc.).  Urban areas appear to be mostly well prepared, as they should be.  Urban water use supports over 90% of California’s economy and population, while using about 10% of its water.

Groundwater levels are declining.  DWR’s new SGMA website shows local and regional trends in groundwater levels (and is a great advance in groundwater data communication).  For the Central Valley, there continues to be sizable declines in groundwater levels in many areas, particularly the San Joaquin Valley and now in parts of the Sacramento Valley.  The need to replenish the additional pumping of this drought, as well as accumulating overdraft since 2014, during the hopefully coming wet years will extend the agricultural impacts of this drought for many years to come, especially if 2040 sustainability targets are to be met.

Rural communities often struggle in drought and from accumulating groundwater contamination.  State aid seems more available and organized than in previous droughts.  But we still have a long way to go on these problems.

Ecosystems impacts of drought remain California’s sector with the least drought management success.  For waterbirds, we seem relatively well organized and mostly successful.  But not for most fish and forests, with post-drought impacts extending for many years from wildfires and more species becoming more endangered.

What to do?

The previous drought highlighted the need to manage groundwater and resulted in California’s Sustainable Groundwater Management Act.  This drought confirms the need to move solidly and deliberately to implement this law at the aquifer level, which will reduce irrigated acreage by 500,000 – 1,000,000 acres permanently.  This will be painful, but necessary for long-term rural health, prosperity, and ecosystems across drought and wetter years.  State and county education and development programs can help ease and accelerate this unavoidable transition.

This drought highlights the growing urgency and unavoidability of reducing agricultural and urban water uses, and the needs to rationalize environmental water management and rural water supplies. 

In the meantime, stay calm and hopeful, but prepare for both floods and drought, as usual.

Further reading

Precipitation data: https://cdec.water.ca.gov/precipapp/get8SIPrecipIndex.action

Reservoir data: https://cdec.water.ca.gov/reservoir.html

Groundwater data: https://sgma.water.ca.gov/CalGWLive/#groundwater

Here is a data garden to play in:  http://cdec.water.ca.gov/reportapp/javareports?name=8STATIONHIST

Medellín-Azuara, J., et al. (2022). Economic Impacts of the 2020-2022 Drought on California Agriculture (2022). A report for the California Department of Food and Agriculture. Water Systems Management Lab. University of California, Merced 35p. Available at http://drought.ucmerced.edu

Howitt, R.E., D. MacEwan, J. Medellín-Azuara, J.. Lund, D.A. Sumner (2015). “Economic Analysis of the 2015 Drought for California Agriculture”. Center for Watershed Sciences, University of California – Davis, Davis, CA, 16 pp.

Howitt, R.E., Medellin-Azuara, J., MacEwan, D., Lund, J.R. and Sumner, D.A. (2014). Economic Analysis of the 2014 Drought for California Agriculture. Center for Watershed Sciences, University of California, Davis, California. 20p.

Jay Lund is a Professor of Civil and Environmental Engineering and Vice-Director of the Center for Watershed Sciences at the University of California – Davis