A key challenge examined in Sommer’s report is the issue of sea level rise, which makes the Delta’s aging and subsiding 1100-mile levee system increasingly vulnerable to flooding and failure. The threat is magnified by the risk of a major earthquake, which by most accounts the Bay Area is due for. For example, in 2009, the US Geological Survey predicted that there is a 62% chance of a 6.7-magnitude or greater earthquake striking the Bay Area in the period between 2003 and 2032.
“We have to come up with solutions, otherwise events will decide them for us – and that almost never works out well.”
A levee failure could result in a rush of saltwater into the Delta, a scenario sometimes referred to as the “big gulp.” A recent report by the National Academies of Science [PDF] stated that saltwater intrusion – by way of a major levee breach, or the steady creep of saltwater from rising ocean levels – could result in a decline in the volume of water available for irrigation and drinking water by as much as 25% by the end of the century. “We’re in a race to mitigate all those risks. But we have one small problem – it’s hugely expensive,” Mount explains. “The existing bonds that have already been authorized are insufficient to really tackle this.”
But, as Mount concluded, the costs of not taking action on the Delta’s problems are unquestionably larger. “It’s the hub of California’s water supply and it’s the weak link in the chain,” says Mount. “We have to come up with solutions, otherwise events will decide them for us – and that almost never works out well.”
Part three of the “Deadlocked Delta” series airs Monday morning on KQED 88.5. The entire series, including exclusive web features, is archived at the QUEST site.