Troubled waters

Get your boats and rafts ready. The Sacramento-San Joaquin river system is one of the most vulnerable to extreme flooding in the country and on the verge of collapse due to poor water management, the watchdog group American Rivers said.

In its recent report on the most endangered rivers in the country, the group ranked the Sacramento-San Joaquin system second on the list (last year it was first). The report says roughly half a million people, freshwater supplies and a diverse ecosystem are at risk.

“The ranking hasn’t received as much attention this year, but the threats are still huge,” Amy Kober, communications director for American Rivers, said. “It is hard to find another river that comes close to having as a big a threat to the public from flooding.”

The threats to the river system have been building for decades, as human engineering has altered the course of the river system—a vital waterway that drains the western slope of the Sierra Nevada and feeds the largest estuary on the West Coast.

As the water flows to the Pacific, much of it is diverted for irrigation or freshwater supplies. At the same time, century-old levees built to protect low-lying communities, particularly Sacramento and Stockton, constrict water unnaturally to river beds and are increasingly outdated.

“The levees weren’t properly designed, engineered or built with the proper material,” Steve Rothert, California regional director for American Rivers, said. “They consist mostly of peat soil mounded on top of each other.”

The earthen design of the levees and increasingly stormy weather attributed to climate change have significantly increased the risk of levee failure or overtopping. With much of the region below sea level, extreme flooding from snow melt or heavy rainstorms could inundate low-lying communities. Such flooding would also shut down the water supply for roughly 23 million people.

Tough financial times have also added to the precarious state of the levees.

“Local management agencies responsible for levee maintenance and inspection are hurting for cash right now,” Mike Mierzwa, a supervisory engineer and spokesman for the California Department of Water Resources, told SN&R. “Levees are extremely expensive to maintain, and [the lack of cash] increases the risk.”

In response to these concerns, state and federal agencies in partnership with independent organizations are working on a variety of solutions.

Bond measures passed by voters in 2006 are funding the Central Valley Flood Protection Plan. The plan centers on updating antiquated levees and the weakest parts of the Central Valley’s flood-control system, with a goal of a 200-year level of protection.

In development by the Sacramento Area Flood Control Agency, the U.S. Army Corps of Engineers and the California Department of Water Resources, the flood-control plan could include setting levees farther back from the river side and allowing for more natural flooding. Although roughly 95 percent of the Sacramento-San Joaquin’s natural flood plain and tidal habitat has been developed, the flood plain is still seen as a critical natural sponge for absorbing water.

Flood easements are another tool under consideration to help restore lost flood plains. As part of the flood easements program, state agencies would pay some landowners to allow for flooding on their land when needed. Notches in levees could also more gradually allow for natural flooding.

According to Mierzwa, the flood-control plan has to be submitted by January 1, 2012, to the Central Valley Flood Protection Board. The board will then decide whether to accept the plan or if alterations are needed.

For now, the state has had a $500 million levee-repair program in place since 2006. So far, 100 of the 250 most critical levee repair sites have been completed.

A related Bay Delta Conservation Plan also aims to sustain the supply of fresh water while also restoring the river system’s ecosystem. Due by mid-year 2011, the plan includes a controversial canal that would funnel water around the Delta and aims to restore water flow to more natural patterns.

In Washington, D.C., Rep. Doris Matsui, who has described Sacramento as the most at-risk river city in the nation, has advocated for reducing flood-insurance rates, remapping flood zones and improving public safety. This July, she passed legislation to make flood insurance more affordable for those living in flood zones such as Natomas. The plan allows for higher rates to be phased in rather than imposed all at once.

Meanwhile in California, the California Department of Water Resources is about to discuss its flood-control action plans in a series of public workshops. The first workshop takes place on July 19.

Even so, the final result of the plan could be a long ways off. According to Mierzwa, a final strategic plan is expected between 2012 and 2017.

“We are really at a crossroad now in terms of river protection and deciding what we want,” American Rivers’ Kober said.

Until that happens, area residents, human and otherwise, will have to go with the existing flow—and hope those levees hold.