wHen tHe wells run dry

Groundwater iMPacts froM california’s excePtional drouGHt

by Pete Dennehy, Abhishek Singh, and Azita Asadi

When it comes to drought conditions, 2022 was the year of records in California. The 3-year period from water year 2020 through water year 2022 (which ended September 30th) is the driest 3-year period on record, breaking the recent record set by the previous drought from 2013 to 2015. The period from 2001 to 2022, is the driest 22-year period on record in at least 1,200 years, surpassing the severity of the megadrought in the late 1500s1. Over this 22-year period, the state has been in drought nearly half of the past two decades. At the time of writing this article in late 2022, more than 90% of the state was experiencing a severe drought, more than 40% was in the midst of extreme drought, and about 17% was facing exceptional drought conditions (Figure 1). A “triple dip” La Niña, originally expected to last through 2022 and early 2023, portends a drier than average winter for much of the southwest. As a result, communities, environment, and agricultural sectors are facing exceptional challenges from depleted reservoir storage, greater reliance on groundwater pumping, and reduced groundwater recharge.

Note: After preparing this article, several atmospheric rivers brought heavy precipitation to much of the state during late December 2022 and early January 2023. With precipitation in the Central Valley totaling greater than 200% of normal2, drought outlook has dramatically improved. However, 22 years of largely drought conditions have left a serious water deficit that a single wet year cannot likely reverse.

While much of the state has begun to implement Groundwater Sustainability Plans (GSPs) after years of plan preparation, the plans are being tested in the immediate face of this historic drought and the associated difficult groundwater management decisions that must be made to balance supply shortages and the achievement of sustainability.

In the past year, DWR has released numerous tools and reports, more than ever before, that make data more transparent and available in real time and are being used to quantify the impacts of drought. These tools include California Groundwater Live, the Dry Well Reporting System, California Data Exchange Center for surface water conditions, and quarterly InSAR subsidence surveys.

Dry Wells. DWR’s California Groundwater Live provides real time analysis of groundwater conditions. In October 2022, 64% of monitoring wells in the state had below normal water levels and about 21% of wells were at an all-time low (Figure 2).

Declining groundwater levels have caused many wells to go dry, particularly shallow domestic wells. In the last year, about 1,700 dry wells have been reported throughout the state, which is more than any year since the reporting system was launched in 2013 (Figures 3 &4). Because domestic wells are typically shallow, residents in disadvantaged communities with shallow domestic wells as their primary source of water supply, are disproportionately impacted.

Land Subsidence. As shallower wells run dry, pumping is shifting to deeper aquifers. In the Central Valley, where overdraft has led to up to 30 feet of subsidence3 in some locations since the 1950s, pumping from deeper levels is known to cause greater compaction of clays that cause subsidence. Despite the passage of SGMA in 2015 and beginning of GSP implementation for Critically Overdrafted Basins in 2020, subsidence has continued in much of the Central Valley, threatening infrastructure like the Delta Mendota Canal and the Friant Kern Canal. These structures are critical for conveying surface water throughout the Central Valley (Figure 5). Subsidence impacts from pumping during the current drought are likely to continue even when the drought ends due to delayed compaction of clay interbeds, which may last several years to decades.4

Interconnected Surface Waters. Groundwater level declines also deplete interconnected surface water, leading to less water in streams for irrigation, community supplies, and habitat. Lowering groundwater levels below the groundwater dependent ecosystems (GDEs) root zone can result in habitat loss. Depletion of interconnected surface water and the effects on GDEs has been identified in GSPs as a data gap in much of the state. Also, stream depletion from groundwater level declines can have a lag and not be realized for years after set in motion.

Water Quality Degradation. Recent research has found that lowering groundwater levels may also be related to regional water quality degradation. The United States Geological Survey Water Science Center indicates that lowering groundwater levels accelerate nitrate contamination of supply wells in the Central Valley5 by drawing down the water table closer to supply well screens, as shown in Figure 6. Drought conditions and declining groundwater levels can also deteriorate groundwater quality by concentrating contaminants or inducing deeper (or coastal) brackish groundwater to move into the productive zones in aquifers. Shift from Surface Water Supply to Groundwater. Growers and irrigation water districts are currently faced with unprecedented water supply challenges. Surface water supplies that rely on Central Valley Project, State Water Project, and Colorado River deliveries are seeing supplies dwindle. This year, the Bureau of Reclamation announced a 0% allocation for the Central Valley Project for irrigation districts and 25% for cities. Similarly, State Water Project allocations were slashed from 15% at the start of the year to 5% in spring. Due to its senior water rights on the Colorado River, the state has not seen curtailments on Colorado River deliveries; however, with Lake Mead at critical water levels, continued declines may trigger cutbacks on California deliveries, impacting municipal and agricultural users across Southern California. With uncertainty surrounding surface water supply, many growers have been forced to turn exclusively to groundwater to meet their crop demands, or alternatively fallow their fields. According to the U.S. Department of Agriculture, an estimated 531,00 farmland acres went unplanted this year due to lack of water.6

State Actions to Manage Drought Conditions. The bright side of historic drought for groundwater managers, is that drought related issues have the full attention of DWR and the governor’s office. The following summarize key measures taken to manage the drought, mitigate its impacts, and provide relief across the state:

• Over the last three years, state leaders have earmarked $8 billion to modernize water infrastructure and management, which enabled emergency drought response as well as projects by local and state agencies to address current and future droughts impacts and to become more resilient. As of October 3, 2022, DWR has provided over $480 million in grant funding through its Small Community and Urban and Multi-benefit Drought Relief programs. This summer, the Legislature approved hundreds of millions in additional funding and programs to support water stressed communities.7

• During the current drought, Governor Newsom has issued several drought emergency proclamations that direct DWR and other agencies to actively respond to the current conditions. Drought proclamations have called agencies to implement actions to provide drinking water assistance, local well permitting coordination, and regulatory relief of groundwater recharge projects under specified circumstances to mitigate drought impacts. Governor Newsom has asked all Californians to reduce water usage at home by 15%.

• The governor issued Executive Order N-7-22, which requires that new well permits to consider sustainable groundwater conditions in the basin, and ensure that new wells do not decrease the likelihood of achieving groundwater sustainability goals, interfere with production of existing wells, or cause additional subsidence.

• Residents with dry wells can get help from a state program that provides bottled water as well as storage tanks regularly filled by water delivery trucks. The state also provides money to replace dry wells, but there’s a long wait to get a new one.

The benefits of SGMA and the associated GSPs are being put to the test as projects and management actions are being funded and implemented. Filling data gaps and improved monitoring will help to quantify the groundwater impacts of drought. Hopefully, the financial investments and lessons learned from this exceptional drought will make groundwater basins more resilient to the extended and pervasive drought conditions that appear to be the new normal.

Figure 1. California Drought Levels as of October 2022, Source: https://droughtmonitor.unl.edu/ CurrentMap/StateDroughtMonitor.aspx?CA

Figure 2. California Groundwater Live Monitoring Wells with below normal water levels, Source: https://storymaps.arcgis.com/stories/b3886b33b49c4fa8adf2ae8bdd8f16c3

Figure 3. Number of Dry Wells Reported Since 2013 tHe wells run dry

Figure 6. Conceptual model of the effects of overdraft on hydraulic head change (Δh) and groundwater quality at a drought-sensitive production well. Source: https:// cawaterlibrary.net/wp-content/ uploads/2021/09/Levy-et-al.pdf

Figure 4. Dry Well Locations Reported Since 2013, Source: DWR Dry Well Reporting System https://tableau.cnra.ca.gov/t/DWR_SGM/views/ mydrywatersupply/Map.pdf

Subsidence

Endnotes:

1 https://data.cnra.ca.gov/dataset/californias-groundwater-semi-annual-conditionsupdates/resource/7e57614f-9868-4d2e-bbb80621be558b9c

2 https://water.ca.gov/Current-Conditions

3 https://agupubs.onlinelibrary.wiley.com/doi/ full/10.1029/2021WR031390

4 https://agupubs.onlinelibrary.wiley.com/doi/ full/10.1029/2021WR031390

5 https://cawaterlibrary.net/wp-content/ uploads/2021/09/Levy-et-al.pdf

6 https://apnews.com/article/californiadroughts-climate-and-environmente49c8c5c34ead7ef7f83b770082f20bc

7 https://water.ca.gov/News/NewsReleases/2022/Oct-22/New-Water-Year-BeginsAmid-Preparations-for-Continued-Drought

The California State Water Resources Control Board (Water Boards) is soliciting Statement of Qualifications (SOQ) from firms that are able to provide groundwater basin studies in support of state intervention pursuant to the Sustainable Groundwater Management Act (SGMA). The Request for Qualifications (RFQ) is open to all eligible firms and/or individuals that meet the minimum qualification requirements. The Water Boards intends to make a single contract award. The Contractor will be selected based on written responses to RFQ No. 22-002-240, plus an oral interview. The RFQ No. 22-002-240 will be advertised by the end of January 2023. Once the RFQ is posted and available, to view the time schedule, proposal requirements, and minimum qualification requirements for this solicitation, please visit http://www.caleprocure.ca.gov. For questions, comments, and inquiries regarding this solicitation, please review the RFQ No. 22-002-240 for the instructions and submission deadlines.

The Water Boards would like to thank you in advance for your interest in our service needs. The bidding process is the mainstay of our competitive system, and your participation is both appreciated and valued.