Professor Kenneth K. Tanji describes California's drought in terms of a water-banking crisis. If not properly handled, it can endanger the quality and quantity of water available in the future, says the water science expert at UC Davis who oversees and coordinates water-quality research and management programs throughout the state. California's surface-water supplies -- a checking account that in normal years meets the state's water needs -- is low. So water-users have begun to draw more extensively on groundwater -- their savings account -- pulling roughly four times more water out of the ground last year in the San Joaquin Valley than in the previous year, for example. Tanji says he anticipates a "severe overdraft" problem during the fifth year of the drought. If too much groundwater is pumped from certain areas, the ground may subside and the water reserves will be difficult to replenish, he says. In addition, farmers must be careful about how they use wells that tap low-quality water as well as drainage water pumped from the ground, so the poorer quality water doesn't degrade the soil surface and prevent seeds from sprouting. Last year, Tanji and colleagues produced a technical manual on salinity designed to help farm advisors and growers deal with these issues.