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Critical Aquifer Overdraft Accelerates Degradation of Groundwater Quality in California's Central Valley During Drought
Author(s) -
Levy Zeno F.,
Jurgens Bryant C.,
Burow Karen R.,
Voss Stefan A.,
Faulkner Kirsten E.,
ArroyoLopez Jose A.,
Fram Miranda S.
Publication year - 2021
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2021gl094398
Subject(s) - aquifer , groundwater , hydrology (agriculture) , water quality , geology , groundwater discharge , environmental science , water resource management , groundwater recharge , ecology , geotechnical engineering , biology
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.