As Oroville spillway ruptures, Sacramento County officials plan ahead for bipolar weather patterns

The heavy rains that fattened Lake Oroville and punched a hole through an eroded auxiliary spillway, displacing more than 180,000 Butte County residents due to flooding risks—yeah, that may just be Mother Nature’s opening act.

With another storm brewing this week, California is experiencing the type of rainfall that hasn’t been seen since its record drought began in 2011. And according to John Lundgren, Sacramento County’s senior planner, these wild pendulum swings between extreme weather patterns may be the standard going forward.

In the second round of an ongoing series of community meetings to develop a countywide climate action plan, local environmental officials convened at the Arden-Dimick Library on February 6, one day before the Oroville Dam spillway that acts as a release valve ruptured into a geyser shooting 100,000 cubic feet of water per second toward the towns below.

Flooding and evacuation notices were reported as far as southern Sacramento County, primarily the towns of Point Pleasant, Wilton and Walnut Grove. Jails in Elk Grove and Oroville were also affected by flooding.

A workshop in the fall focused on the effects of extreme heat—temperatures in excess of 102 degrees Fahrenheit—during the dry summers. (See “Living with the change,” News, November 24, 2016.)

Now, local officials are preparing for the flooding that comes with changing precipitation patterns outlined in a vulnerability assessment prepared by Ascent Environmental Inc. The assessment cited “less-frequent but more extreme storm events” including a higher volume of rain falling within a shorter period of time, as well as more destructive wind patterns.

This, according to Lundgren, is likely to be typical. “The storms we’re seeing in this weather pattern is indicative of climate variability,” Lundrgen said. “We expect that variability to get more severe with climate change.”

Although a search for “climate change” on the Trump administration’s government website brings up only three noncontextual results (none of which relate to climate change), Lundgren said the state of California, not the federal government, will dictate local climate policy.

“Our general plan has mitigation measures that say we need to embark upon this climate action plan,” Lundgren said. “So that’s what we’re doing. Regardless of what the current national political scene is.”

Adaptive efforts presented at the workshop include countywide levee improvements to mitigate extreme flooding. According to an official with the Sacramento Area Flood Control Agency, SAFCA will begin installing seepage cutoff walls within the next two years along six miles of the Sacramento River levee around the Pocket area, and four miles of the river in North Sacramento primarily along Arcade Creek.

Additionally, the U.S. Army Corps of Engineers plans to buffer local river walls with additional erosion protection, though no date for these efforts has been set. The Corps is already at work on a new auxiliary spillway at Folsom Dam, with financial and engineering support from the state. Along with the spillway, the dam will be raised three and a half feet and improvements will be made to the surrounding dikes. Completion is scheduled for later this year.

Revelations emerged this week that environmentalists warned officials to strengthen the Oroville Dam’s spillway more than a decade ago because of concerns about its vulnerability.

Lundgren said Sacramento County is serious about its preparations. “We’re taking a very contemplative, thoughtful [approach to] this,” he told SN&R. “We don’t want to just haphazardly apply climate change measures to the community without thinking how that might impact all the sectors of the community.”

A third round of public workshops are tentatively slated for spring, though no specific date has yet been chosen.