California Groundwater
A Depleted Resource
Introduction
Groundwater, the most accessible source of freshwater available to people across the globe, is being over-exploited, specifically in California (Hanak et al. 2017). Approximately 85% of Californians rely on groundwater for part of their water supply, an ever-increasing number (Hanak et al. 2017). Overdraft, or using more groundwater than is being replenished, is a serious concern for basins across the state (Hanak et al. 2017). Approximately 40% of water usage for farms and cities comes from the ground (Hanak et al. 2017). The overexploitation of these resources due to a lack of action and legislation, both on the state and national levels, is detrimental to the environment and future generations.
Despite the high rain levels that have occurred throughout California this year, the majority of this water doesn't go back into the ground, instead, it flows out to the ocean, as you can see in the visualization app by Sam Learner below. Naturally, wells and basins with little overdraft that are minimally below their standard levels will be brought back to normal, but the most extreme cases of this will hardly be affected. Simply waiting for rainfall will do nothing, as detailed state plans and millions of dollars of funding are required to fix this state-wide issue.
Mapbox allows people to view where a raindrop would end up from anywhere in the world
Background
Basins, defined by alluvial aquifers or a stacked series of them, are three-dimensional figures, with both well-defined boundaries and a measurable bottom, meaning they include groundwater (Groundwater Basin 2023). As a reserve, or "saving account", the basins provide water when the surface water supply is depleted, which is most common during dry years (Groundwater Basin 2023). There are 515 ground basins in California (Kennedy 2014).
Rainwater, just flowing through the river, is unlikely to just seep into the ground, as it takes significant time for the water to physically go into basins. The fast flow of river water is a challenge in bringing the water into the ground, making recharge basins and irrigated agriculture a prominent solution, as the water has time to soak in. As a result of government plans, the excessive rainwater and snowmelt will be diverted into recharge basins and irrigated agriculture, as injection wells are slow and not cost-effective.
The Sustainable Groundwater Management Act (SGMA), when creating sustainability standards for basins, created six indicators of over-drafting of wells; groundwater-level declines, land subsidence, seawater intrusion, groundwater-storage reductions, interconnected surface-water depletions, and water-quality degradation (Sustainable Groundwater Management). This map represents the number of indicators addressed by groundwater projects.
Droughts, a prominent problem dating back decades in California, is even more hurtful today as groundwater storage continues to deplete. Especially as the water supply becomes a dire topic, it is essential that the groundwater supply is replenished in order to mitigate the negative effects of droughts.
Based on the largest and most prominent aquifer in each ecological region, this map represents both deep and shallow aquifers with high and low recharge. Shallow aquifers, although they are easier to access and less expensive, provide less water and are less conductive compared to deep aquifers (4 Differences in...). With high conductivity and more water, deep aquifers are harder to access and more expensive, as the water has to be pumped from deeper underground (4 Differences in...). The natural recharge, or the amount of water going from an unsaturated area or on the surface into the aquifer, is a determinant of how much water can be sustainably pumped from an aquifer (Nimmo 2009).
In California, there are two primary groups of wells, single wells, and nested/multi-completion wells. Making up the large majority of wells, single, or individual monitoring wells, consist of a single casing string within a borehole (Monitoring Wells Standards). On the other hand, nesting wells, or multi-completion wells, feature two or more casing strings within the well to obtain water from different aquifers or water-bearing zones (Monitoring Wells Standards). Although nesting wells are able to obtain this water, they are incredibly difficult to construct as one has to ensure that each casing scene is hydraulically isolated (Monitoring Wells Standards).
Across California, the most common wells are observation wells, or monitoring wells, that observe groundwater levels and flow conditions, providing data that allows governments to see the overdraft of wells. Irrigation wells, accounting for a large portion of Californian wells, are primarily used at farms, whether for cattle or for agriculture. Both public supply wells and residential wells provide water to towns and individuals. Overall, there is a wide variety of wells found in California and multiple types of groundwater usage that need to be taken into account when finding solutions for this problem.
History
1990s-2000s: State-Incentivized Groundwater Management
Although no official legislation was made, the state encouraged the use of groundwater management at a local level (Horton 2020). Funding was provided for studies on groundwater and California-enabled involvement in groundwater (Horton 2020).
2014: Sustainable Groundwater Management Act (SGMA)
The first Californian law on groundwater is implemented, regulating the usage of this source. Utilizing local groundwater sustainability agencies, SGMA gathers data and monitors water usage across the state (Everything You Need...) Groundwater Sustainability Agencies(GSAs) were implemented throughout the state and the government ensured that their Groundwater Sustainability Plans (GSPs) were up to date with current requirements and assisted in the execution of them (Everything You Need...).
2023: Executive Order to Restore Groundwater
It takes away restrictions that prohibit water agencies and water users from restoring groundwater (Governor Newsom Issues...). Utilizing the influx of floodwater and snowmelt, the order provides clear guidelines and allows for a boost in groundwater storage (Governor Newsom Issues...).
Problem
Basin Prioritization
Basin Prioritization
In order to determine the prioritization of each basin, SGMA utilized eight characteristics; the population above the basin, the growth of said population, the number of public supply wells that drew from the basin, the number of wells that draw from the basin, the number of irrigated acres above the basin, the degree of to which it was used as a primary source of water, documented impacts on the groundwater within the basin, and any other information relevant to the basin and its health (Groundwater Monitoring Program 2009). From this information, the government sorted all 515 basins into high prioritization, medium prioritization, low prioritization, and very low prioritization. It is evident that basins in the central and San Joaquin Valley require the most care and are the most depleted, primarily from farming and an overreliance on groundwater due to a high need for water from water-intensive plants, such as almonds.
Groundwater Levels
In areas such as the San Joaquin Valley, the depleted water levels are so drastic that this influx of rain will be far from fixing the problem. On top of the plans that must be constructed and carried out by the government, there must be a drastic reduction in the amount of water pumped, both by farms and communities. Groundwater pumping is essential in bringing up the levels of water in these wells, some of which are 700 feet below the standard levels (Bland 2023). As many as 750, 000 acres of farmland could be out of production due to state laws, which would temporarily assist in reducing the need for groundwater, but would largely damage the Californian economy (Bland 2023).
Groundwater Level Changes
Throughout California, there has been an overall negative change in groundwater levels across hundreds of thousands of wells. The central area of California has been the most negatively impacted, in some cases losing over 10 feet in the well on average. This stems from the overdraft of certain basins, specifically in their low supply and extraordinarily high demand. It is instrumental that, when considering solutions for groundwater, the demand and use of the water are mitigated, as only altering the supply will do little.
SGMA, a protector against the over-drafting of groundwater, is set to have a long-term solution in 2040, yet the problem exists now. In places such as the Central Sierra, local governments are preparing to capture the melted snow and put it back into the ground. In the Tulare Irrigation District, stormwater is diverted into ponds, where it will end up recharging the groundwater stores (Bland 2023). On top of this, farmers who sink water into their fields during the wet season and storms are able to get it back during a dry stretch. Daily, 1500 acre-feet are being brought in by the district, the majority of which is going straight back into the ground (Bland 2023)
SGMA defines sustainable groundwater management as the “management and use of groundwater in a manner that can be maintained during the planning and implementation horizon without causing undesirable results.”
Effect of Wells
Well Density vs. Basin Prioritization
When comparing well density to basin prioritization, there is a direct correlation found between the number of wells in a given area and its likeliness to have a high or medium prioritization rating by the Californian government. This contributes to the idea that overdraft is the primary reason behind the lower water levels in basins and wells across the state.
Lower Income Wells
Lower-income populations, when building wells, are the first to have theirs dry out. Well cost, a function of well depth, limits the water supply given by shallow wells, especially as groundwater levels are decreasing year by year (Robert Fogg Personal Communication 2023). On top of this, in areas such as the Central Valley, where farming is common, agricultural practices create contamination in basins, which spread to shallow wells. Shallow wells, primarily built by lower-income residents, are highly susceptible to both drying out and becoming contaminated (Robert Fogg Personal Communication 2023).
Tulare Lake
“Tulare Lake is back, and it may take over and put us out.” - Martina Sealy
The recent extremely high rainfall has resulted in Tulare Lake coming back. Tulare Lake, as a large pool of water that is just sitting there, will sink into the ground, recharging the basin below it. Yet this comes at a high price, with thousands of people being affected, and forced out of their homes, by this sudden influx of water. As snowmelt increases from the Sierras, Tulare Lake will only grow bigger, bringing devastation to these people, their homes, and their livelihoods.
Impact
Subsidence
Subsidence, at record levels in California, is detrimental to infrastructure, from roads to structures to buildings. Aquifer mediums, which become compact, not only permanently reduce storage but also lower the height of the land, most commonly found in the Central and San Joaquin Valleys (Halverson 2015).
Over the last 20 years, 90% of subsidence has come from the deepest layer of groundwater compacting (Garthwaite 2022). The collapsing of these aquifers, due to overdraft, has permanently resulted in 6 trillion gallons of groundwater storage lost (Halverson 2015). In order to stop subsidence, groundwater levels not only need to stop decreasing, but they need to increase (Garthwaite 2022).
Salt Water Intrusion
Saltwater intrusion, or freshwater aquifers becoming saltwater, stems from reducing freshwater flows against saline water, which is found on the coast and very deep in aquifers (Saltwater Intrusion 2019). As overdraft occurs, saltwater is drawn to freshwater zones as it goes inland and upward, making freshwater wells salinated, or incredibly impractical (Saltwater Intrusion 2019). From overdraft of wells, the well as a whole is unable to be pumped, decreasing the freshwater supply in California.
Reduction of Surface Water
Groundwater, a major source of water for rivers and streams through streambeds, has an altered movement course from pumping (Groundwater Decline and Depletion 2018). Current California legislation attempts to protect the downstream user with surface water, yet the overdraft of groundwater can also negatively impact the downstream consumer, cementing the idea that California should enforce stricter groundwater pumping laws that have an impact in the present day (Groundwater Decline and Depletion 2018).
Solutions
Where to Get Water
Flood flow, or high magnitude river flow, is a viable solution known as flood-MAR (managed aquifer recharge). By taking the upper 10% of the river flow, there wouldn't be a negative environmental impact, yet lots of water would be able to be brought into the ground (Robert Fogg Personal Communication 2023). Over a decade, few opportunities will occur such as this and the government recognizes this. The executive order made by Gavin Newsom cuts down many of the red tape and restrictions concerning surface water that would prevent this from happening which are in place to protect downstream consumers (Robert Fogg Personal Communication 2023).
Snow, at a record high this year in the Central Sierra, is an incredible opportunity to bring water into the ground (Robert Fogg Personal Communication 2023). Due to the risk of flooding by overfilling reservoirs, a lot of this snow melt will need to go into the ground. In the areas near this incredible amount of snow, the levels of groundwater will greatly increase.
“That snow is going to melt, and we want the local water districts to be positioned to capture some of that excess snowmelt and get it underground.” - Karla Nemeth
Ocean water, which is able to be used as a supplement for groundwater, has extremely limited potential. Coastal cities in California, such as Los Angeles and San Diego, are wealthy, which allows them to be able to desalinize seawater, but only in small amounts due to the high costs of energy that end up drastically increasing the price of water (Robert Fogg Personal Communication 2023). If desalinized water, the most expensive water on Earth, was used for irrigation or agricultural purposes, the price of food would skyrocket, increasing the world hunger crisis.
Economically, when comparing recharging groundwater, expanding reservoirs to store water on the surface, and the desalinization of water, it is apparent that recharging groundwater is the most cost-effective option. Approximately costing $390 per acre-foot, recharging groundwater is over $1500 cheaper than either of the other two options per acre-foot, with desalinizing water being the most expensive (Cost Comparison...).
Minimizing Demand
Despite decades of extensive pumping, there have been little to no efforts to replenish groundwater, and it is instrumental that proactive change is made. 97% of liquid freshwater is in the ground and it takes incredibly large amounts of pumping before the negative change will occur as changes in groundwater systems are slow (Robert Fogg Personal Communication 2023).
Groundwater agencies often “emphasize solutions on the supply side, and relatively little on the demand side … and the supply numbers do not add up” - 2020 PPIC Analysis
In California, the strong majority of food grown is nonessential, such as pistachios, almonds, avocados, grapes, and other nuts (Robert Fogg Personal Communication 2023). These foods are both not staples in any diet and not preventing hunger across the globe. By cutting back on the growth of these foods, which require astronomical amounts of water to produce, there will be a significantly smaller demand for water and this farmland can be replaced with solar farms or less water-intensive foods that are staple crops (Robert Fogg Personal Communication 2023).
Percentage of Crops being Almonds Compared to Groundwater Level Change
Putting Water in the Ground
From climate change, just as how experts predicted, the dry season in California is just getting dryer and the wet season is getting wetter, yet the annual average precipitation in California remains the same (Robert Fogg Personal Communication 2023). As a state, surface storage of water is overly relied upon and won't allow for enough storage during these extended dry periods (Robert Fogg Personal Communication 2023). Groundwater has the ability to allow for more water storage, but only if effective measures are used to bring the water into the ground.
“We know that climate change is essentially putting the weather on steroids and giving us greater and greater chances of seeing these extremely heavy precipitation events and severe floods, even as we also see more severe droughts and that in the same part of the world.” - Daniel Swain
By spreading the water across farmland in areas such as the Central Valley during the nongrowing season, no energy is required or purification is needed to put the water back into basins (Robert Fogg Personal Communication 2023). Known as Ag-MAR (agricultural managed aquifer recharge), this process has been led by Terranova Ranch. On the flip side, it can harm farmlands that need to be dry in order to be cultivated or permanent plants such as trees (Robert Fogg Personal Communication 2023).
Recharge basins, which have been proven to be successful, are ponds that have connections to groundwater, with the water sinking in through the surface (Robert Fogg Personal Communication 2023). Across California, this has been proven to be successful as shown in the Kern River recharge basins in Bakersfield, which use flood flows in the recharge basins (Robert Fogg Personal Communication 2023). Directly pumping into wells is an inefficient solution as the water has to be pure. On top of that, it is a time-consuming process to pump water into the ground.
Across the state, demand for groundwater must be reduced and recharge should be drastically increased. Through a multifaceted solution, California will be able to emerge with a plan that allows the state to bring back the levels of groundwater and ensure that no one is negatively impacted. It is the responsibility of every resident of California to make a change and educate others about the problems of the past and the promise of the future.
Works Cited
Hanak, E., Chappelle, C., & Harter, T. (2017). Groundwater in California. Public Policy Institute of California. https://www.ppic.org/publication/groundwater-in-california/#:~:text=Groundwater%20is%20a%20vital%20component,portion%20of%20their%20water%20supply.
(n.d.). Groundwater Basin. Open Computing Facility Berkeley. Retrieved April 10, 2023, from https://www.ocf.berkeley.edu/~lchahal/groundwater-in-ca/groundwater-basin/
Kennedy, C. (2014, August 27). Groundwater: California's Big Unknown. Climate.gov. Retrieved April 11, 2023, from https://www.climate.gov/news-features/event-tracker/groundwater-california%E2%80%99s-big-unknown
(n.d.). Sustainable Groundwater Management. USGS. Retrieved April 9, 2023, from https://ca.water.usgs.gov/sustainable-groundwater-management/
(n.d.). 4 Differences in Shallow Groundwater and Deep Groundwater. Deep Ocean Facts. Retrieved April 13, 2023, from https://deepoceanfacts.com/differences-in-shallow-groundwater-and-deep-groundwater
Nimmo, J. R. (2009, January 16). Aquifer Recharge. Science Direct. Retrieved April 14, 2023, from https://www.sciencedirect.com/topics/earth-and-planetary-sciences/aquifer-recharge
(n.d.). Monitoring Wells Standard. California Department of Water Resources. Retrieved April 11, 2023, from https://water.ca.gov/Programs/Groundwater-Management/Wells/Well-Standards/Combined-Well-Standards/Monitoring-Introduction
Horton, M. (2020, June 11). The Past, Present and Future of California's Groundwater. Stanford: Water in the West. Retrieved April 9, 2023, from https://waterinthewest.stanford.edu/news-events/news-insights/thepast-present-and-future-californiasgroundwater
(n.d.). Everything You Need to Know About California's Historic Water Law. The Guardian. Retrieved April 10, 2023, from https://www.theguardian.com/environment/2020/feb/27/california-groundwater-sgma-law-what-does-it-mean
(n.d.). Governor Newsom Issues Executive Order to Use Floodwater to Recharge and Store Groundwater. Office of Governor. Retrieved April 10, 2023, from https://www.gov.ca.gov/2023/03/10/governor-newsom-issues-executive-order-to-use-floodwater-to-recharge-and-store-groundwater/
(n.d.). Groundwater Monitoring Program 10933. California Legislative Information. Retrieved April 16, 2023, from https://leginfo.legislature.ca.gov/faces/codes_displaySection.xhtml?sectionNum=10933.&lawCode=WAT
Bland, A. (2023, February 7). Ground zero: Rain brings little relief to California’s depleted groundwater. Cal Matters. Retrieved April 8, 2023, from https://calmatters.org/environment/water/2023/02/california-depleted-groundwater-storms/
Halverson, N. (2015, June 25). 9 sobering facts about California’s groundwater problem. Reveal News. Retrieved April 13, 2023, from https://revealnews.org/article/9-sobering-facts-about-californias-groundwater-problem/
Garthwaite, J. (2022, June 2). Groundwater depletion causes California farmland to sink. Stanford study shows water levels must rise to halt subsidence. Stanford: News Service. Retrieved April 14, 2023, from https://news.stanford.edu/press-releases/2022/06/02/will-californiasley-stop-sinking/
(2019, March 2). Saltwater Intrusion. USGS. Retrieved April 15, 2023, from https://www.usgs.gov/mission-areas/water-resources/science/saltwater-intrusion
(2018, June 6). Groundwater Decline and Depletion. USGS. Retrieved April 14, 2023, from https://www.usgs.gov/special-topics/water-science-school/science/groundwater-decline-and-depletion
(n.d.). Cost Comparison of Water Projects. Stanford: Water in the West. Retrieved April 10, 2023, from https://waterinthewest.stanford.edu/groundwater/charts/cost-comparison/index.html
