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- Title
Critical Aquifer Overdraft Accelerates Degradation of Groundwater Quality in California's Central Valley During Drought.
- Authors
Levy, Zeno F.; Jurgens, Bryant C.; Burow, Karen R.; Voss, Stefan A.; Faulkner, Kirsten E.; Arroyo‐Lopez, Jose A.; Fram, Miranda S.
- Abstract
Drought‐induced pumpage has precipitated dramatic groundwater‐level declines in California's Central Valley over the past 30 yr, but the impacts of aquifer overdraft on water quality are poorly understood. This study coupled over 160,000 measurements of nitrate from ∼6,000 public‐supply wells with a 30 yr reconstruction of groundwater levels throughout the Central Valley to evaluate dynamic relations between aquifer exploitation and resource quality. We find that long‐term rates of groundwater‐level decline and water‐quality degradation in critically overdrafted basins accelerate by respective factors of 2–3 and 3–5 during drought, followed by brief reversals during wetter periods. Episodic water‐quality degradation can occur during drought where increased pumpage draws shallow, contaminated groundwater down to depth zones tapped by long‐screened production wells. These data show, for the first time, a direct linkage between climate‐mediated aquifer pumpage and groundwater quality on a regional scale. Plain Language Summary: It has been established that wells are at risk to run dry when groundwater levels decline during drought, but associated impacts to water quality are poorly understood. This study examined 30 yr of data from California's Central Valley to find dramatic groundwater‐level declines during drought were associated with worsening groundwater quality. This likely happens because increased pumping during drought can draw shallow, contaminated groundwater to depths commonly tapped by public drinking‐water wells. This is the first study of its kind to show direct linkages between drought and groundwater quality at such a broad spatial scale. Key Points: Drought‐induced pumpage has precipitated dramatic groundwater‐level declines in California's Central Valley over the past 30 yrLong‐term rates of groundwater‐level decline and water‐quality degradation in overdrafted basins accelerate by factors of 2–5 during droughtIncreased pumpage during drought can draw shallow, contaminated groundwater down to depths tapped by long‐screened production wells
- Subjects
CENTRAL Valley (Calif. : Valley); CALIFORNIA; GROUNDWATER quality; DROUGHTS; AQUIFERS; RESOURCE exploitation; OVERDRAFTS; WATER quality; WATER table; WATER levels
- Publication
Geophysical Research Letters, 2021, Vol 48, Issue 17, p1
- ISSN
0094-8276
- Publication type
Article
- DOI
10.1029/2021GL094398