A new flood protection plan approved Friday for California's Central Valley takes a firm stand against a U.S. Army Corps of Engineers policy that could require trees and shrubs to be stripped from levees in the region.

The new Central Valley Flood Protection Plan calls for improvements over several decades that are estimated to cost $17 billion.

It will be funded initially by $5 billion in flood-control bonds approved by state voters in 2007. It likely will require another $5 billion bond, plus local and federal matching funds.

The plan will guide flood-safety improvements for the foreseeable future and must be updated every five years.

Its many projects include enlarging the Yolo Bypass, adding a flood bypass on the San Joaquin River, building more setback levees to widen river channels, and setting new operating criteria at dams to heed weather conditions and a changing climate.

Mandated by 2008 legislation, the plan aims to achieve 200-year flood protection in urban areas while improving wildlife habitat and protecting agriculture in rural areas. It is the most comprehensive effort of its kind in a century.

The Central Valley Flood Protection Board, a state agency, approved the plan unanimously after months of public hearings. It was ultimately supported by environmental groups and flood-control agencies.

Ronald Stork, senior policy analyst at Friends of the River, called the plan "a thoughtful framework for future improvements to the flood system that promises to be more river- and environment-friendly."

The board made two major changes to the draft plan, prepared by engineers at the state Department of Water Resources. The biggest deals with a 2007 Corps policy allowing only grass on levees.

The state has been negotiating with the Corps for years to amend the policy, arguing that removing millions of trees threatens wildlife habitat and would yield little flood-protection benefit.

After those negotiations stalled, the state Department of Fish and Game earlier this year filed suit, saying the Corps failed to follow the Endangered Species Act and other federal laws in adopting the rule.

The flood board agreed with that assertion. The new plan approved Friday makes it official state policy that California will not follow the Corps vegetation rule.

Instead, when approving future flood-control projects, the board will allow trees and shrubs on the lower, water-side sections of all levees. Also, all other existing vegetation is allowed to remain on levees "until the end of the natural life" of those plants.

Both conditions are subject to pruning criteria so levees can be inspected.

The board also postponed a proposal for a new flood bypass on the Feather River until the plan's 2017 update, saying it needs further study.

"We listened carefully to residents and flood experts, farmers, property owners and local governments, levee districts, scientists and environmentalists," board President Bill Edgar said in a statement.

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