Thursday, July 7, 2011

California groundwater management trickles up from local sources

Science Daily: In a typical year, California gets about 30 percent of its water from groundwater wells. Yet when it comes to managing this precious resource, the state of California relies on a mixed bag of more than 2,000 local water agencies with varying degrees of authority.

Critics say that this decentralized system leaves the state vulnerable to overdraft, which occurs when water is pumped out faster than replacement water is absorbed. But according to a new report published by Stanford University's Program on Water in the West, a surprising number of local water districts are taking on the challenge of groundwater protection, even without state leadership.

"Contrary to popular expectations, our report uncovers a treasure trove of innovative strategies for groundwater management in California," said the paper's author, Rebecca Nelson, a former Australian water lawyer who is now a graduate student in the Stanford Law School.

"The California legal framework for groundwater management is weak," Nelson said. "It doesn't compel local districts to do anything, so many of them don't. But there are these gems in the rough. This report highlights the work of some of these outstanding managers."

To evaluate how well groundwater is managed in California, Nelson first had to overcome the lack of basic information about groundwater management in the state. Because California lacks a centralized data clearinghouse, she had to contact more than 50 local districts and request copies of their groundwater management plans -- if they had any. "Maybe on two hands you could count the districts that acknowledge the environmental effects of over-pumping," Nelson said.

This lack of statewide data is a problem not only for researchers but also for local water agencies wishing to learn from each other and develop a comprehensive regional strategy, she said...

Approximate location of maximum subsidence in the United States identified by research efforts of Dr. Joseph F. Poland (pictured). Signs on pole show approximate altitude of land surface in 1925, 1955, and 1977. The site is in the San Joaquin Valley southwest of Mendota, California. The compaction of unconsolidated aquifer systems that can accompany excessive ground-water pumping is by far the single largest cause of subsidence. The overdraft of such aquifer systems has resulted in permanent subsidence and related ground failures. In aquifer systems that include semiconsolidated silt and clay layers (aquitards) of sufficient aggregate thickness, long-term ground-water-level declines can result in a vast one-time release of “water of compaction” from compacting aquitards, which manifests itself as land subsidence. US Geological Survey photographer

1 comment:

groundwater consultants said...

Groundwater is stored in the ground in materials like gravel or sand. It's kind of like the earth is a big sponge holding all that water. Water can also move through rock formations like sandstone or through cracks in rocks.