Water rights far exceed flows
A study shows the state has allocated five times its annual runoff
California over the last century has issued water rights that amount to roughly five times the state’s average annual runoff, according to new research that underscores a chronic imbalance between supply and demand.
That there are more allocations than water in most years is not news. But UC researchers say their study is the most comprehensive assessment to date of the enormous gap between natural surface flows and rights.
Water allocations — excluding those for hydropower production — exceed natural runoff on 16 major California rivers. Among the most over-subscribed are the San Joaquin, Kern and Stanislaus rivers in the San Joaquin Valley and the Santa Ynez River in Southern California.
In theory, that difference is not necessarily a problem. It gives water agen- cies and irrigation districts with junior rights access to additional supplies during wet years, when runoff is above average and there is plenty to go around. But in reality, it fosters unrealistic expectations for water that is often not available, study coauthor Joshua Viers said.
“It gives the public a false sense of water security,” said Viers, a UC Merced professor of water resources. For the most junior rights holders, he said, “It’s kind of like standing in line to get into a concert and they give you a ticket when they’re already at capacity. But you don’t know that you’ll never actually get in to see the show.”
The study, published online Tuesday in the journal Environmental Research Letters, analyzed public data from the State Water Resources Control Board, which administers water rights, and compared it with estimates of natural surface flow.
Although the annual statewide flow averages 70 million acre-feet, water rights issued since 1914 allocate 370 million acre-feet for a variety of purposes, including agriculture, domestic use and hydropower production. (An acre-foot of water is sufficient to supply two households for a year.)
“What is most compelling about this,” Viers said, is “that the appropriated rights are so much more than the actual full natural f low. In many cases, we’ve five to 10 times over-promised.”
Moreover, the state database does not account for riparian rights granted to stream-side landowners or pre-1914 rights, under which some irrigation districts and cities claim huge amounts of water. “So in many ways our estimate is a substantial underestimate of the total volume of rights,” he said.
Viers conducted the study with Ted Grantham, now a U.S. Geological Survey scientist, when Grantham was a postdoctoral researcher at UC Davis.
The authors say that the
‘Without supervision of distribution, appropriative water rights are meaningless.’ —Michael Hanemann,
UC Berkeley professor
state board has spotty information on actual water use by rights holders, hampering its ability to do its job.
“We’re not lacking in technology and know-how,” said Viers, who argued that the state is short on funding and “the political will” to develop information and monitoring systems to strengthen water-rights oversight.
“We need both better information infrastructure and policy in order to make better decisions about water use in California,” he said.
Michael Hanemann, a UC Berkeley professor of environmental and resource economics who was not involved in the study, said the issue is not so much that the state has issued too many water rights. Rather, he said, California doesn’t properly enforce them — or in the case of 19th century rights, even know exactly who is entitled to what.
“Without supervision of distribution, appropriative water rights are meaningless,” Hanemann said. “We do not have a coherent system for allocating water.”
The state continues to issue water rights, mostly on small streams on the North Coast, said Amanda Montgomery, a water-rights manager for the state board. She said the staff checks senior rights and fishery needs when reviewing the filings.
“We have the system we have, and we do our absolute best to implement it effectively,” she said. “We’re always looking toward program improvements.”