We've thought about drilling offshore for oil and gas long before we thought about finding fresh water there. A recent review paper in Nature has brought the topic of offshore fresh groundwater to wider visibility.
Drilling mud is the slick concoction used to cool and lubricate a drill bit, and it’s used for all kinds of wells, including oil and gas. Environmental groups are turning their attention to drilling mud, which is currently exempted from water monitoring.
As vineyards proliferate around this farm town halfway between Los Angeles and San Francisco, residential wells are starting to go dry. Some are calling the plight of Paso Robles a good example of what's wrong with California's unregulated groundwater supply.
Spent reactor fuel and other high-level radioactive wastes may be better off in soft rocks than hard ones.