Report: State's big rivers in big trouble Environment

California's two longest rivers, the Sacramento and the San Joaquin, were named the nation's most endangered waterways by an environmental group that considers them threatened by outdated water management and poor flood planning.

American Rivers, a conservation group that compiles the annual list, chose the Sacramento-San Joaquin river system because its collapse could threaten the water supply of 25 million Californians, flood the state's capital and damage the delicate freshwater delta where the two rivers twine.

"The Sacramento-San Joaquin Delta is on the verge of losing important fish species, and the communities that surround it already don't have adequate protection from their levees," said Steve Rothert, California director of the Washington, D.C., nonprofit.

State water officials did not immediately comment on the new report.

The Sacramento and the San Joaquin meet in the delta, a freshwater estuary surrounded by an aging network of fragile levees. That system has harmed the rivers' floodplains, a crucial habitat for fish and other species that use that area to feed and reproduce, Rothert said.

The delta also forms the heart of the state's water-delivery system, where snowmelt from the Sierra Nevada is rerouted through canals and pumps to reach millions of Californians and thousands of acres of croplands.

President Barack Obama signed a wilderness bill last week that implements a 2006 legal settlement to bring water and Chinook salmon back to a portion of the state's second-longest river, the San Joaquin. It provides about $390 million in federal and state funds in the next decade.