PHOENIX (AP) â€” California and six other states were on the verge of a historic agreement that would give Southern California a 15-year deadline to cut its use of Colorado River water.
If California fails to follow through with a series of interim water-saving steps, the grace period would end immediately and upriver states could start withholding water from the nation's most populous state.
``California has to follow through or it will be at risk of not having the water supply it needs for Southern California,'' said Deputy U.S. Interior Secretary David Hayes.
The threat of punishment for California is key to getting Arizona, Colorado, Nevada, New Mexico, Utah and Wyoming to go along with the plan, Hayes said.
A draft of California's Colorado River Water Use Plan, released after representatives met privately Thursday, said the state could reduce reliance on the river water without hurting urban or agricultural areas.
The plan would result in California reducing its river water use by up 1 million acre-feet per year and developing programs for water conservation, reuse, storage and recovery of groundwater and surface water. An acre-foot is about 326,000 gallons, or a year's supply for a family of four.
Besides conserving water, California would store any wet-year surplus in giant new reservoirs such as 4,500-acre Diamond Valley Lake, which began filling in March. That reservoir may be able to hold 260 billion gallons of Colorado River water when it is available, instead of letting unused portions drain away.
Some states are concerned that California has delayed conservation projects, such as the $200 million lining of the All-American Canal to prevent water leakage. Lining the earthen canal with cement is projected to produce about a third of the water savings required under the proposed pact.
Under a 1922 agreement, California, Arizona and Nevada share 7.5 million acre-feet of Colorado River lower basin water with California getting 4.4 million, Arizona 2.8 million and Nevada 3,000.
The upper basin apportionment is also 7.5 million acre-feet with Colorado receiving 3.8 million, Utah 1.7 million, Wyoming 1 million and New Mexico 838,000 in a normal year.
However, California's average demand over the last decade has been about 5.2 million acre feet and the state has traditionally taken surplus water from Arizona and Nevada.
The other states want California to revert back to its 4.4 million acre-feet annual allotment.
Tom Hannigan, director of the California Department of Water Resources, said his state has had to spend a lot of time trying to win the trust of the other states in the negotiations.
``We're working on one plan now,'' he said. ``Hopefully we're close.''
For more than 100 years, the Colorado has been dammed, drained and diverted into canals and pipelines, making it one of the most managed rivers in the world â€” and one of the most environmentally threatened. More than 100 species are considered endangered.
The river supplies water to more than 20 million people in the United States and Mexico, not to mention millions of acres of wheat, alfalfa and other crops.
Competition for the water â€” the West's most prized natural resource â€” is growing.
Phoenix and Las Vegas are among the fastest-growing cities in America, and their desert suburbs are sucking up underground water supplies, making them more reliant on the river.
California's population, meanwhile, is expected to grow from around 32 million to 47.5 million by 2020.
Interior Secretary Bruce Babbitt warned last year that unless California began conserving, he might stop declaring surpluses in other states that allow California to take more than its allotted share.
About three-quarters of California's share goes to farming in the southeastern part of the state.
Officials from other states realize California can't halt its overuse immediately.
Wayne Cook, executive director of the Upper Colorado River Commission, which represents Colorado, New Mexico, Utah and Wyoming, said the water use plan amounts to a ``soft landing'' for California.
``It's better to have seven states in agreement than six against one,'' said Herb Dishlip, who represents Arizona and Nevada in negotiations. ``It will be better to put this issue of California's overuse behind us.''