Deep groundwater quality in the southwestern United States

Kang, Mary; Ayars, James E.; Jackson, Robert B.

doi:10.1088/1748-9326/aae93c

Cited by 24 publications

(15 citation statements)

References 28 publications

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“…State definition for groundwater to be protected varies, and oil and gas activities are widespread in underground sources of drinking water DiGiulio et al, 2018;Kang et al, 2019a;Kang et al, 2020), defined by the U.S. Environmental Protection Agency as waters that may be usable with treatment (DiGiulio et al, 2018). Groundwater wells in the United States are increasingly being drilled deeper (Perrone and Jasechko, 2019), and brackish water previously considered too saline to be used is being treated or blended with fresher water (Kan and Rapaport-Rom, 2012) to meet water quality requirements.…”

Section: Barriers and Limitations Of Well Pluggingmentioning

confidence: 99%

Orphaned oil and gas well stimulus—Maximizing economic and environmental benefits

Kang

Brandt

Zheng

et al. 2021

Elementa: Science of the Anthropocene

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Orphaned oil and gas wells are abandoned wells for which the cost of environmental impacts usually falls on governments and the general public. Government agencies responsible for well plugging often face funding shortfalls and many orphaned wells remain unplugged. To address this and support the oil and natural gas industry, federal governments are already spending, or considering spending, billions of dollars to plug orphaned oil and gas wells. Here, we analyze oil and gas data for the United States and Canada and identify policy recommendations that can best address environmental impacts of abandoned and orphaned wells. At least 116,245 wells across 32 states and four Canadian provinces/territories are operated by companies filing for bankruptcy in the first half of 2020, which may be an indication that many wells will be orphaned in the near future. Moreover, there are 4,700,000 historic and active oil and gas wells in the United States and another 790,000 in Canada. Of these, 2,000,000 and 310,000 wells are active in the United States and Canada, respectively. Thus, three of five wells ever drilled in the United States are currently inactive (2,700,000 wells), but only one in three are plugged (1,500,000 wells). Plugging involves isolating zones containing oil, gas, and water and is the main strategy for well abandonment. If the orphaned well stimulus funding comes through, tens of thousands of wells will be plugged within a few years. Well plugging at this scale far exceeds current rates of plugging, and it is important that we work to ensure long-term environmental benefits of well abandonment to water, air, climate, ecosystems, and human health. Minimizing environmental impacts of the millions of abandoned and orphaned wells in the United States, Canada, and abroad will allow for an economically beneficial and environmentally safe transition to a carbon-neutral economy.

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Section: Barriers and Limitations Of Well Pluggingmentioning

confidence: 99%

Orphaned oil and gas well stimulus—Maximizing economic and environmental benefits

Kang

Brandt

Zheng

et al. 2021

Elementa: Science of the Anthropocene

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“…A previous study considered depths up to 3,000 m and concluded that there is 3 to 4 times more fresh water in the Central Valley than previously estimated (20). This and other previous studies (20,21) analyzed groundwater TDS data, which are determined from sampling groundwater or oil and gas wells, or applying geophysical methods. Importantly, the previous studies did not perform spatially distributed analysis and did not account for depths of groundwater wells being pumped to meet domestic, agricultural, or industrial water demands.…”

mentioning

confidence: 82%

“…California's Central Valley hosts immense stores of fresh water, especially at depth (20,21), and managing deep groundwaters in the Central Valley and throughout California may prove strategic. A previous study considered depths up to 3,000 m and concluded that there is 3 to 4 times more fresh water in the Central Valley than previously estimated (20).…”

mentioning

confidence: 99%

“…Using the interpolations, we evaluated the distribution and volumes of fresh (TDS > 3,000 mg/L) and brackish (TDS of 3,000 mg/L to 10,000 mg/L) water. We use a TDS threshold of 3,000 mg/L to be consistent with previous studies (20,21) for the volume estimates. We analyzed the TDS distributions to gain insights on data density and range of TDS values, which are important to consider when comparing the base-of-freshwater data to TDS measurements and groundwater production well depths.…”

mentioning

confidence: 99%

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Base of fresh water, groundwater salinity, and well distribution across California

Kang

Perrone

Wang

et al. 2020

Proc. Natl. Acad. Sci. U.S.A.

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The depth at which groundwaters transition from fresh to more saline—the “base of fresh water”—is frequently used to determine the stringency and types of measures put in place to manage groundwater and protect it from contamination. Therefore, it is important to understand salinity distributions and compare defined bases of fresh water with salinity distributions and groundwater well depths. Here we analyze two distinct datasets: 1) a large set of total dissolved solids concentration (TDS) measurements (n= 216,754) and 2) groundwater well locations and depths (n= 399,454) across California. We find that 19 to 56% of the groundwater TDS measurements made at depths deeper than defined bases of fresh water pump fresh groundwater (TDS < 2,000 mg/L). Because fresh groundwater is found at depths deeper than the base of fresh water, current policies informed by base of fresh water assessments may not be managing and protecting large volumes of deep fresh groundwater. Furthermore, we find that nearly 4% of existing groundwater wells penetrate defined bases of fresh water, and nearly 16% of wells overlie it by no more than 100 m, evidencing widespread encroachment on the base of fresh water by groundwater users. Consequently, our analysis suggests that groundwater sustainability in California may be poorly safeguarded in some places and that the base-of-fresh-water concept needs to be reconsidered as a means to define and manage groundwater.

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“…These include hydrologic alteration caused by surface water storage and conveyance systems (Döll et al 2009), as well as groundwater depletion, a global challenge occurring primarily in areas of high agricultural development (Siebert et al 2010, Scanlon et al 2012, Famiglietti 2014. Groundwater overdraft leads to higher pumping costs, poorer water quality (Kang et al 2019), decreased well yields (Konikow and Kendy 2005), and land subsidence (Smith et al 2017, Jeanne et al 2019. These issues are exacerbated under poor governance as water users have little incentive to conserve (Ho et al 2016), particularly when individual extraction leads to collective depletion of a common pool resource (Hardin 1968).…”

Section: Introductionmentioning

confidence: 99%

Water shortage risks from perennial crop expansion in California’s Central Valley

Mall

Herman

2019

Environ. Res. Lett.

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California's Central Valley is one of the world's most productive agricultural regions. Its high-value fruit, vegetable, and nut crops rely on surface water imports from a vast network of reservoirs and canals as well as groundwater, which has been substantially overdrafted to support irrigation. The region has undergone a shift to perennial (tree and vine) crops in recent decades, which has increased water demand amid a series of severe droughts and emerging regulations on groundwater pumping. This study quantifies the expansion of perennial crops in the Tulare Lake Basin, the southern region of the Central Valley with limited natural water availability. A gridded crop type dataset is compiled on a 1 mi 2 spatial resolution from a historical database of pesticide permits over the period 1974-2016 and validated against aggregated county-level data. This spatial dataset is then analyzed by irrigation district, the primary spatial scale at which surface water supplies are determined, to identify trends in planting decisions and agricultural water demand over time. Perennial crop acreage has nearly tripled over this period, and currently accounts for roughly 60% of planted area and 80% of annual revenue. These trends show little relationship with water availability and have been driven primarily by market demand. From this data, we focus on the increasing minimum irrigation needs each year to sustain perennial crops. Results indicate that under a range of plausible future regulations on groundwater pumping ranging from 10% to 50%, water supplies may fail to consistently meet demands, increasing losses by up to 30% of annual revenues. More broadly, the datasets developed in this work will support the development of dynamic models of the integrated water-agriculture system under uncertain climate and regulatory changes to understand the combined impacts of water supply shortages and intensifying irrigation demand.

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Deep groundwater quality in the southwestern United States

Cited by 24 publications

References 28 publications

Orphaned oil and gas well stimulus—Maximizing economic and environmental benefits

Orphaned oil and gas well stimulus—Maximizing economic and environmental benefits

Base of fresh water, groundwater salinity, and well distribution across California

Water shortage risks from perennial crop expansion in California’s Central Valley

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