By now we have all seen the spectacular images of volumes of water crashing down the Oroville Dam spillway in California and blasting upward into the air as they hit an enormous crater in the spillway floor, flooding down the adjacent hillside, threatening people in towns below. Those images reveal a big mistake: failure to update infrastructure to defend against climate change.
The menacing floodwaters last week forced the emergency evacuation of 188,000 residents. Yet the impending disaster came as no surprise to officials in Butte and Plumas counties. The rural counties, which surround Lake Oroville, had challenged the state’s environmental review of dam operations in a 2008 lawsuit, arguing the state “recklessly failed” to properly account for climate change in its long-term dam management plan.
The dam was built in the 1960s when temperatures were cooler and more precipitation was stored in a greater snowpack in the mountains of the Feather River watershed, which drains into Lake Oroville. Today warming temperatures are bringing more rain as well as melting the Sierra Nevada snowpack earlier in the spring. As the counties’ attorneys predicted, among the results is a rush of downhill water much faster than in the past. “We anticipated that this crisis might come about,” says Tony Rossmann, special counsel to Butte County.
That’s exactly what happened a week ago, leading to the crater. With the reservoir brimming over from rain and rapid snowmelt, and the spillway maxed out as the crater widened, officials activated Oroville’s never-used unpaved emergency spillway—a broad hillside a short distance from the spillway along the same dam wall. The combination of rocks, trees and floodwaters pummeling down toward the cities below the dam forced the mandatory evacuations. Hard rain is happening again today as new storms continue to deluge the area 150 miles north of San Francisco.
The California Department of Water Resources (DWR) owns and manages the Oroville reservoir as part of the State Water Project, a massive utility providing water to 23 million residents and farmers as far south as Los Angeles County. When its dam license expired in 2007, DWR applied to the Federal Energy Regulatory Commission (FERC) for a 50-year renewal.
The ensuing lawsuit by the two counties challenged the environmental review that was part of the renewal process. In response, DWR attorneys said their environmental analysis adequately considered climate change “based on the limited information available at the time.” They called specific information about climate change in the Feather River watershed “too speculative” to include.