Groundwater recharge in California

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Groundwater recharge is the process of water being absorbed into the ground from precipitation, snowmelt, or artificial processes. Intentional groundwater recharge uses large, open basins that allow water to slowly seep into the ground. This water is filtered by sediment while traveling underground and is pumped back to the surface as a source of freshwater. In California, groundwater accounts for around 41% of the state's total water supply, [1] although this number varies between wet and dry years. During years of greater than average rainfall, less groundwater is used to allow for reserves to be available during dry years. Up to 60% of all water can be sourced from groundwater during dry years. The amount of water in underground aquifers is carefully monitored by the State Water Resources Control Board and other regional water resource boards. [2]

Contents

Benefits of groundwater recharge

Groundwater recharge is primarily utilized as a method of water storage to safeguard against water scarcity during prolonged years of drought. California's dry climate makes droughts a common occurrence, especially in Southern California. Surface water sources like reservoirs, lakes, and rivers can quickly run low during dry years. Storing water underground during years of increased rainfall relieves pressure from the surface water sources and lessens the need for imported water during dry years.

Another advantage of groundwater recharge is that it is one of the cheapest sources of water available when compared to desalination, recycled water, imported water, or reservoir expansion. [3] [4] As a result, investment into groundwater recharge basins has been steadily increasing in recent years. Groundwater projects are planned to provide an increase of 500,000 acre-feet annually to the water supply. [5] With 2023 being an extreme wet year, California achieved a record-setting 8.7 million acre-feet of groundwater to aquifers. [6]

Legislation

Passed in 2014, the Sustainable Groundwater Management Act (SGMA) regulates the amount of water being received and taken from groundwater basins. [7] The goal of this act is to develop sustainability plans for each groundwater basin in order to keep the groundwater supply balanced. [8] The plans are put in place to avoid overdrafted basins, where the amount of water being taken out is greater than the amount sustainable in the long term. This can be harmful to groundwater because overdrafting makes it more susceptible to contamination from naturally occurring arsenic deposits or chemical pesticides. [9] Overdrafting can also cause underground sources of seawater to leach into aquifers, making the freshwater impure and brackish. Aquifers in the southern Central Valley have become some of the most overdrafted in the state due to the water-dependent agricultural economy of the region. [10] The progress of groundwater sustainability plans by region are supervised by the California Department of Water Resources. [7]

Notable recharge basins in California

Groundwater aquifers are distributed throughout all of California, with a large density of recharge basins located in Southern California around Los Angeles, Riverside, Orange, and San Bernardino counties. Surface water is more prevalent in the north, where residents generally rely less on groundwater for their total water supply. Bay area residents acquire around 20% of their total water from groundwater. [11]

Chino Basin

The Chino Basin is situated along the Santa Ana River Watershed in San Bernardino County. This watershed extends over a large area from the inland mountains surrounding Big Bear all the way to Huntington Beach. The Chino basin program draws water from runoff and snowmelt in the region containing Mount Baldy, Mount San Jacinto, and Big Bear. [12] Water is supplied throughout cities located in southern San Bernardino County including Ontario, Chino Hills, and others.

Future expansion

Groundwater recharge projects are expected to increase in number in future years throughout California due to the comparatively low cost and massive storage capabilities of aquifers. The total volume of groundwater capacity is estimated to be 850 million acre-feet, while there is only around 50 million acre-feet of available surface freshwater in the state. [2] Future groundwater projects plan to exploit this storage capacity and conserve as much water as possible in groundwater sources.

Impact on agriculture

As urban population centers expand throughout California, an increasing amount of groundwater has been diverted to cities and away from agriculture. Around 62% of total water goes to California's large agricultural industry. [13] The most produced products in California include dairy, almonds, and grapes. Producing these products needs a large amount of water and requires farmers to practice efficient farming methods. Agriculture is one of the biggest industries in California and contains some of the most profitable farmland in the United States. [13] Protection of groundwater resources is vital for maintaining California's multi-billion dollar agricultural sector and sustaining the regions that depend on Californian exports.

Sustainability and environmental impact

Water recharge projects maintain close communication with biologists and other researchers to ensure native habitats and species are not negatively impacted by basin construction. Protected species are closely monitored to ensure that projects will not impede on their habitats. Protected species in California include the Santa Ana Suckerfish and the Kangaroo Rat.

Related Research Articles

<span class="mw-page-title-main">Aquifer</span> Underground layer of water-bearing permeable rock

An aquifer is an underground layer of water-bearing material, consisting of permeable or fractured rock, or of unconsolidated materials. Aquifers vary greatly in their characteristics. The study of water flow in aquifers and the characterization of aquifers is called hydrogeology. Related terms include aquitard, which is a bed of low permeability along an aquifer, and aquiclude, which is a solid, impermeable area underlying or overlying an aquifer, the pressure of which could lead to the formation of a confined aquifer. The classification of aquifers is as follows: Saturated versus unsaturated; aquifers versus aquitards; confined versus unconfined; isotropic versus anisotropic; porous, karst, or fractured; transboundary aquifer.

<span class="mw-page-title-main">Groundwater</span> Water located beneath the ground surface

Groundwater is the water present beneath Earth's surface in rock and soil pore spaces and in the fractures of rock formations. About 30 percent of all readily available freshwater in the world is groundwater. A unit of rock or an unconsolidated deposit is called an aquifer when it can yield a usable quantity of water. The depth at which soil pore spaces or fractures and voids in rock become completely saturated with water is called the water table. Groundwater is recharged from the surface; it may discharge from the surface naturally at springs and seeps, and can form oases or wetlands. Groundwater is also often withdrawn for agricultural, municipal, and industrial use by constructing and operating extraction wells. The study of the distribution and movement of groundwater is hydrogeology, also called groundwater hydrology.

<span class="mw-page-title-main">California Aqueduct</span> Water supply project in California, US

The Governor Edmund G. Brown California Aqueduct is a system of canals, tunnels, and pipelines that conveys water collected from the Sierra Nevada Mountains and valleys of Northern and Central California to Southern California. Named after California Governor Edmund Gerald "Pat" Brown Sr., the over 400-mile (640 km) aqueduct is the principal feature of the California State Water Project.

Fossil water, fossil groundwater, or paleowater is an ancient body of water that has been contained in some undisturbed space, typically groundwater in an aquifer, for millennia. Other types of fossil water can include subglacial lakes, such as Antarctica's Lake Vostok. UNESCO defines fossil groundwater as "water that infiltrated usually millennia ago and often under climatic conditions different from the present, and that has been stored underground since that time."

<span class="mw-page-title-main">Edwards Aquifer</span> Source of drinking water in Texas

The Edwards Aquifer is one of the most prolific artesian aquifers in the world. Located on the eastern edge of the Edwards Plateau in the U.S. state of Texas, it is the source of drinking water for two million people, and is the primary water supply for agriculture and industry in the aquifer's region. Additionally, the Edwards Aquifer feeds the Comal and San Marcos Springs, provides springflow for recreational and downstream uses in the Nueces, San Antonio, Guadalupe, and San Marcos river basins, and is home to several unique and endangered species.

<span class="mw-page-title-main">Westlands Water District</span>

Westlands Water District is a water district in central California, a local-government entity formed in 1952, that holds long-term contracts for water supplied by the Central Valley Project and the California State Water Project.

<span class="mw-page-title-main">Groundwater recharge</span> Groundwater that recharges an aquifer

Groundwater recharge or deep drainage or deep percolation is a hydrologic process, where water moves downward from surface water to groundwater. Recharge is the primary method through which water enters an aquifer. This process usually occurs in the vadose zone below plant roots and is often expressed as a flux to the water table surface. Groundwater recharge also encompasses water moving away from the water table farther into the saturated zone. Recharge occurs both naturally and through anthropogenic processes, where rainwater and/or reclaimed water is routed to the subsurface.

<span class="mw-page-title-main">Overdrafting</span> Unsustainable extraction of groundwater

Overdrafting is the process of extracting groundwater beyond the equilibrium yield of an aquifer. Groundwater is one of the largest sources of fresh water and is found underground. The primary cause of groundwater depletion is the excessive pumping of groundwater up from underground aquifers. Insufficient recharge can lead to depletion, reducing the usefulness of the aquifer for humans. Depletion can also have impacts on the environment around the aquifer, such as soil compression and land subsidence, local climatic change, soil chemistry changes, and other deterioration of the local environment.

The Turlock Basin is a sub-basin of the San Joaquin Valley groundwater basin which occupies approximately 13,700 total square miles, making it the largest groundwater basin in California. The Turlock Basin makes up 542 square miles of this total. This aquifer is located within Merced and Stanislaus counties in the Central Valley bounded by the Tuolumne River to the north, the Merced River to the south and San Joaquin River to the west. The Sierra Nevada foothills bound the sub-basin to the east. Groundwater in the San Joaquin Valley occurs mostly in younger alluvial material. The Turlock Basin lies to the east of the city of Turlock. Groundwater in the Turlock Basin occurs in older alluvial deposits. Large portions of the San Joaquin Basin have experienced overdraft of water and infiltration of agricultural water pollutants, resulting in poor water quality.

<span class="mw-page-title-main">Surface water</span> Water located on top of land forming terrestrial bodies of water

Surface water is water located on top of land, forming terrestrial waterbodies, and may also be referred to as blue water, opposed to the seawater and waterbodies like the ocean.

<span class="mw-page-title-main">Water in California</span> Water supply and distribution in the U.S. state of California

California's interconnected water system serves almost 40 million people and irrigates over 5,680,000 acres (2,300,000 ha) of farmland. As the world's largest, most productive, and potentially most controversial water system, it manages over 40 million acre-feet (49 km3) of water per year. Use of available water averages 50% environmental, 40% agricultural and 10% urban, though this varies considerably by region and between wet and dry years. In wet years, "environmental" water averages 61%, while in dry years it averages 41%, and can be even lower in critically dry years.

Groundwater banking is a water management mechanism designed to increase water supply reliability. Groundwater can be created by using dewatered aquifer space to store water during the years when there is abundant rainfall. It can then be pumped and used during years that do not have a surplus of water. People can manage the use of groundwater to benefit society through the purchasing and selling of these groundwater rights. The surface water should be used first, and then the groundwater will be used when there is not enough surface water to meet demand. The groundwater will reduce the risk of relying on surface water and will maximize expected income. There are regulatory storage-type aquifer recovery and storage systems which when water is injected into it gives the right to withdraw the water later on. Groundwater banking has been implemented into semi-arid and arid southwestern United States because this is where there is the most need for extra water. The overall goal is to transfer water from low-value to high-value uses by bringing buyers and sellers together.

The Sustainable Groundwater Management Act (SGMA) is a three-bill package that passed the California state legislature and was signed into California state law by Governor Jerry Brown in September 2014. Its purpose is to ensure better local and regional management of groundwater use and it seeks to have a sustainable groundwater management in California by 2042. It emphasizes local management and formed groundwater sustainability agencies (GSAs) from local and regional authorities who submitted groundwater sustainability plans (GSPs) to the state between 2020 and 2022.

<span class="mw-page-title-main">Water reuse in California</span>

Water reuse in California is the use of reclaimed water for beneficial use. As a heavily populated state in the drought-prone arid west, water reuse is developing as an integral part of water in California enabling both the economy and population to grow.

The Central Valley in California subsides when groundwater is pumped faster than underground aquifers can be recharged. The Central Valley has been sinking (subsiding) at differing rates since the 1920s and is estimated to have sunk up to 28 feet. During drought years, the valley is prone to accelerated subsidence due to groundwater extraction. California periodically experiences droughts of varying lengths and severity.

<span class="mw-page-title-main">Groundwater Ambient Monitoring and Assessment Program</span>

The Groundwater Ambient Monitoring and Assessment Program (GAMA) is an all-inclusive monitoring program for groundwater that was implemented in 2000 in California, United States. It was created by the California State Water Resources Control Board as an improvement from groundwater programs that were already in place.

Borrego Valley Groundwater Basin, located in the very southern region of California, is one of the driest basins in the state. With climate change predicted to have strong effects into foreseeable future, the region is viewed with a skepticism in the sustainable use of water at current rates of consumption. Both natural and man-made geographic divisions within this basin allow for a closer inspection of the various management techniques implemented throughout the years, and provide a basis for what may be pursued for an uncertain future.

<span class="mw-page-title-main">Central Valley groundwater pollution</span> Groundwater pollution in Central Valley, California

Contaminated groundwater in the Central Valley of California is a growing problem due to contamination and overuse. This problem is compounded by the overdrafting of underground aquifers.

<span class="mw-page-title-main">Fresh water</span> Naturally occurring water with low amounts of dissolved salts

Fresh water or freshwater is any naturally occurring liquid or frozen water containing low concentrations of dissolved salts and other total dissolved solids. Although the term specifically excludes seawater and brackish water, it does include non-salty mineral-rich waters such as chalybeate springs. Fresh water may encompass frozen and meltwater in ice sheets, ice caps, glaciers, snowfields and icebergs, natural precipitations such as rainfall, snowfall, hail/sleet and graupel, and surface runoffs that form inland bodies of water such as wetlands, ponds, lakes, rivers, streams, as well as groundwater contained in aquifers, subterranean rivers and lakes. Fresh water is the water resource that is of the most and immediate use to humans.

References

  1. ↑ "Groundwater". water.ca.gov.
  2. 1 2 "Groundwater Recharge". water.ca.gov.
  3. ↑ "Cost Comparison of Water Projects". waterinthewest.stanford.edu.
  4. ↑ "FAQs • How much does our water cost to import?". www.smwd.com.
  5. ↑ "California Increases Groundwater Supply". Governor of California. May 7, 2024.
  6. ↑ "A wet year boosted California's groundwater, but not enough to address long-term declines". Los Angeles Times. May 8, 2024.
  7. 1 2 "Sustainable Groundwater Management Act (SGMA) Status Map". gispublic.waterboards.ca.gov. Retrieved 2024-08-07.
  8. ↑ "Sustainable Groundwater Management Act (SGMA)". water.ca.gov.
  9. ↑ "Aquifers". Water Education Foundation. June 22, 2020.
  10. ↑ "Groundwater in California". Public Policy Institute of California.
  11. ↑ "GroundWater Protection". www.waterboards.ca.gov.
  12. ↑ "Our Water".
  13. 1 2 "California Water 101". Water Education Foundation. June 22, 2020.
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