Arsenic in groundwater has been a problem for a really long time. It’s naturally present in Earth’s crust and a frequent concern in groundwater management because of its ubiquity and links to heart disease, diabetes, cancer and other illnesses. But the idea that overpumping for irrigation could increase arsenic concentrations is new. aquifers contaminated as a result of overpumping can recover if withdrawals stop. How long it takes to recover is going to be highly variable and dependent upon so many factors.
— source Stanford University | Jun 5, 2018