A not-yet-public federal Bureau of Reclamation review of Salton Sea restoration proposals shocked some plan creators who were briefed on it, projecting the cost of their proposals at billions of dollars more than their estimates.

Bureau representatives shared highlights of their preliminary report on Monday with Salton Sea Authority Executive Director Rick Daniels and two officials from the Imperial Irrigation District, representing the so-called Imperial Group.

Both the authority and Imperial Group are coalitions of government representatives, environmental groups, businesses and/or local residents, and each has a plan for Salton Sea restoration under consideration.

The authority's plan, calling for a mid-sea dam to create two lakes, saw "almost a doubling" of its cost under the bureau's estimates, Daniels said.

The bureau's cost estimate of the Imperial Group's proposal is about a five-fold increase, Daniels said. The discrepancy is caused by the bureau following more stringent and expensive federal standards for dams and dykes in both proposals.

Behind the numbers

The Imperial Group plan calls for creating a series of concentric lakes with plastic barriers called geotubes. Although the Imperial Group estimated the cost of that plan at $2.3 billion, the bureau puts it at $4.4 billion. But the bureau also proposed a new design for the Imperial Group plan involving gravel-filled stone columns to support berms. That alternative would cost $14 billion.

Imperial Group members "don't understand how the Bureau of Reclamation numbers can be so different from theirs," said Irv Hamilton, a spokesman for the group.

State officials estimate the authority's "north and south lakes" plan's cost at $5 billion, but the federal bureau's estimate is $9.2 billion. Daniels said the authority's dam standard follows the requirements of the state agency that will ultimately have to sign off on any plan, the California Department of Water Resource's Division of Dam Safety.

Under the authority's plan, the only potential area of flooding in the event of seepage or a dam breach would be a created "salt flat" in the middle of the Salton Sea to which the public would not have access, Daniels said. The federal bureau is "applying a standard as if there were people, property and structures to be protected," he said.

Subject to change

Bureau of Reclamation Salton Sea program manager Michael Walker said the preliminary report was shared Wednesday with bureau and U.S. Department of Interior officials in Washington, D.C.

All of the figures and other data in the federal report are preliminary and subject to change, he said.

The bureau was tasked by an act of Congress with considering Salton Sea alternatives. A parallel process enacted by the California Legislature is ongoing and also considering Salton Sea-saving measures.

The Salton Sea Authority is prepared to challenge the federal cost findings, Daniels said.

"We've got to keep moving this thing forward, because the sea's going to be dead in the next 10 years," he said. "If we keep writing these reports, we're missing the boat."