Salinity of deep groundwater in California: Water quantity, quality, and protection

Abstract

Deep groundwater aquifers are poorly characterized but could yield important sources of water in California and elsewhere. Deep aquifers have been developed for oil and gas extraction, and this activity has created both valuable data and risks to groundwater quality. Assessing groundwater quantity and quality requires baseline data and a monitoring framework for evaluating impacts. We analyze 938 chemical, geological, and depth data points from 360 oil/gas fields across eight counties in California and depth data from 34,392 oil and gas wells. By expanding previous groundwater volume estimates from depths of 305 m to 3,000 m in California’s Central Valley, an important agricultural region with growing groundwater demands, fresh [<3,000 ppm total dissolved solids (TDS)] groundwater volume is almost tripled to 2,700 km3, most of it found shallower than 1,000 m. The 3,000-m depth zone also provides 3,900 km3 of fresh and saline water, not previously estimated, that can be categorized as underground sources of drinking water (USDWs; <10,000 ppm TDS). Up to 19% and 35% of oil/gas activities have occurred directly in freshwater zones and USDWs, respectively, in the eight counties. Deeper activities, such as wastewater injection, may also pose a potential threat to groundwater, especially USDWs. Our findings indicate that California’s Central Valley alone has close to three times the volume of fresh groundwater and four times the volume of USDWs than previous estimates suggest. Therefore, efforts to monitor and protect deeper, saline groundwater resources are needed in California and beyond.

Identification and characterization of high methane-emitting abandoned oil and gas wells

“…The century-and-a-half-long history of oil and gas development in Pennsylvania and other US states, such as Texas and California, has resulted in millions of abandoned wells, and in many cases, poorly documented or missing well records (3,(9)(10)(11). As a result, there is a lack of data to characterize abandoned oil and gas wells and the possible relationship between methane emissions and well attributes.…”

Interdependent Infrastructure as Linked Social, Ecological, and Technological Systems (SETSs) to Address Lock‐in and Enhance Resilience

“…SETS approaches have also been recently applied (or proposed) for reducing the impacts of drought in California. Technologically oriented options being implemented or explored include desalination (such as the 50 million gallons per day Carlsbad Desal Plant near San Diego), groundwater drilling, and wastewater recycling (Cooley et al, ; Gorman, ; Howard & Millsap, ; Kang & Jackson, ; McKenzie, ; San Diego County Water Authority, ; Underwood, ). Ecologically based solutions include the use of more native vegetation in landscaping and the implementation of fog harvesting systems inspired by nature (California Water Service, ; FogNet, ; Goldstein, ; Knickmeyer, ; Weiss‐penzias et al, ).…”

Resource recovery from low strength wastewater in a bioelectrochemical desalination process

“…Algae Growth = +0.050 −3.000E-003 × A +3.000E-003 × B −0.020 × C + 3.750E-003 × AB −3.750E-003 × AC +3.750E-003 × BC −9.545E-003 × A 2 −9.545E-003 × B 2 +0.015 × C 2 Final equation in terms of actual factors: Microalgae Growth = +0.090273 +3.51818E-004 × COD +2.61818E-003 × TDS −0.81818 × Microalgae Absorbance +3.75000E-006 × COD × TDS −3.75000E-004 × COD × Microalgae Absorbance + 3.75000E-003 × TDS × Microalgae Absorbance −9.54545E-007 × COD 2 −9.54545E-005 × TDS 2 +1.54545 × Microalgae Absorbance 2 The results obtained in this work are similar to some of the previous observations using process optimization techniques [49]. In this study, we noticed the interaction and quadratic effects to be significant as reported in other studies focusing on microbial fuel cells [42,[50][51][52][53][54].…”