As he manages the terrible drought, Gov. Jerry Brown has persuaded Californians to reduce their water use by more than 25 percent, and led the campaign to convince voters to approve a $7.5 billion water bond, which will help us get through future droughts with less economic and environmental damage.
But the drought continues to damage the economy and environment. Every extended dry period brings a rush to use more groundwater as rivers turn to trickles and reservoirs recede. This is understandable: Central Valley groundwater supplies are vast, and have sustained cities and farms for decades. But California needs restraints on new pumping.
Heavy pumping, even in normal or wet years, has consequences. Groundwater levels are dropping in parts of the Central Valley much faster than they have for decades. This causes increased energy use and air pollution, as pumps work harder to bring water to the surface. Rivers rely on groundwater to augment their flow. Over-pumping groundwater depletes the flow of the rivers.
In parts of the Central Valley where the soil is made up of sand and gravel, groundwater pumping does not affect the surface level of the ground. In these areas, it is possible during periods of heavy rain and runoff to put water back in the ground, restoring groundwater levels.
In other areas, however, the soil compacts and sinks as groundwater is withdrawn. This lost space below ground can never be regained. Even worse, the surface of the ground declines. In some areas, this is not a serious problem: the farmland is relatively flat and there is little impact on farming or infrastructure.
But in other areas the surface decline due to subsidence is causing serious problems. The U.S. Geological Survey has found that the surface elevation near the vital California Aqueduct has declined a foot or more just this year. This decline has greatly affected canals, wells, roads and other infrastructure in various Central Valley locations.
The canal that diverts water to the Central California Irrigation District from the San Joaquin River now barely flows in the right direction. Bridges are sinking. Perhaps most seriously, the declining ground surface is lowering levees, which could lead to terrible floods when the rivers rise again.
Over-pumping causes problems for residential and community water use as well. Thousands of domestic wells have failed in recent years because they are shallower than irrigation wells.
The First Rule of Holes applies: when you are in a hole, stop digging. Some counties like Glenn County have responded to this crisis by prohibiting the drilling of new wells. But other counties, sympathetic to farmers who have no other water supply but groundwater, have been reluctant to act.
Department of Water Resources Director Mark Cowin has stated: “We don't believe we can sustain this type of pumping.” The economic damage caused by sinking groundwater and surface levels must be addressed.
The governor should use his emergency powers under the existing drought to ban new wells in areas where groundwater pumping is causing significant economic damage.
I don’t take this position lightly. I understand it would harm people who need groundwater to keep their farms going.
But their economic benefits are outweighed by the costs that local government and the state face to repair infrastructure. People seeking to drill new wells are not likely to agree to pay for the damage they cause to roads, levees, and other infrastructure by their pumping.
The new well ban could end when the governor declares the drought over. In the meantime, the governor should encourage a more robust system of trading groundwater and surface supplies to alleviate the economic damage of constrained groundwater pumping.
Gerald H. Meral is former deputy director of the California Department of Water Resources and former deputy secretary of the California Natural Resources Agency.