Few people realize how outdated our systems for water information are. Because of data limitations, real-time, transparent decisions about drought management, flood response and groundwater protection have eluded the state for the past century. Without basic numbers on where, when and how much water is available and being used, we can’t improve how we manage our most precious water and natural resources.
Sacramento County advised residents in the Tyler Island area south of Walnut Grove to evacuate Monday due to a compromised levee. About 20 homes are in the area, said Sacramento County Water Resources spokesman Matt Robinson. Tyler Island is protected by a ring levee. The county expected imminent failure of the North Fork Mokelumne River levee, the National Weather Service warned early in the afternoon. Robinson said there was some disintegration on the land side of the levee but no water has gotten through. Workers are piling rocks at the weakened point to shore it up, he said.
It wasn’t so long ago that residents here had to drag their houseboats into a dusty field from the barren banks of Lake Oroville, which had almost no water left to keep them afloat. Now after weeks of rain, that dusty field is swelling with water and nearly 200,000 people had to evacuate the area when the state’s second-largest reservoir developed a hole in its auxiliary spillway and threatened to catastrophically flood nearby towns.
Federal officials Monday ordered California to convene a five-member independent board of dam experts to review the condition of Oroville’s auxiliary spillway and the damaged regular concrete spillway, and to make recommendations about how to improve safety during the emergency and over the long-term. In a letter to the state Department of Water Resources, the Federal Energy Regulatory Commission also required the state to hire “a fully independent third party” to perform a “forensic analysis” to determine the cause of the main spillway failure and whether it could occur again.
With more storms expected to slam Northern California later this week, officials worked frantically Monday to drain water from brimming Lake Oroville in hopes of heading off a potentially catastrophic flood. The operators at America’s tallest dam found themselves in a precarious position Monday, with both of the spillways used to release water compromised and the reservoir still filled almost to capacity after a winter of record rain and snow. Meanwhile, tens of thousands of evacuated residents downstream of the dam still have no clear word when they can return home.
Any dam engineer would be terrified of this nightmare scenario — the possible collapse of a retaining wall in California’s second largest reservoir. That’s the prospect officials faced when they ordered more than 100,000 people evacuated downstream of the nation’s tallest dam Sunday. It occurred insidiously: a pocket of erosion that crept ever closer to a low concrete wall that was supposed to be the last, best defense against disaster.
Eleven years ago, as three environmental groups were urging the state and federal government to require that concrete be used to armor the emergency spillway at Oroville Dam — an earthen spillway whose near collapse caused the evacuation of 200,000 people this week — state water officials said that was unnecessary. “The spillway is a safe and solid structure founded on solid bedrock that will not erode,” the state Department of Water Resources concluded in a May 26, 2006, filing to federal officials.
Here are some central questions and answers about the damage to the Oroville Dam and the fight to prevent a catastrophe: What is the Oroville Dam? Work on the Oroville Dam — the tallest dam in the country at 770 feet — started in 1957 and included the relocation of California State Route 70 and Union Pacific Railroad tracks. It was completed in 1968, creating what is now the second-biggest reservoir in the state, sitting on the Feather River about 75 miles north of Sacramento in Butte County.
Federal and state officials have a lot to answer for in the wake of the Oroville Dam fiasco. They decided in 2005 to ignore warnings that the massive earthen spillway adjacent to the dam itself could erode during heavy winter rains — which it has done — and cause a calamity, which it very nearly did this week and could yet do by the end of this winter. No less to blame are the water agencies, including the powerful Metropolitan Water District of Southern California, which argued that paying for the upgrades a decade ago was unnecessary.
North state senators Ted Gaines and Jim Nielsen expressed their disagreement last week with the California State Water Resources Control Board’s decision to extend the state’s emergency drought regulations. Gaines, who represents the 1st Senate District that includes Siskiyou County, stated in a press release that by voting to extend the regulations, urban water districts will be subject to an additional 270 days of consumption reports, “stress tests,” and water-use cuts. “This decision is blind to the plain fact seen on every mountain, river and reservoir in the north state,” Gaines said.
The Water News Network is San Diego County’s source for water news and information.
