Feb 14, 2017

Flooding concerns at Oroville Dam as water levels reach capacity

Oroville, CA
Tom Di Liberto
NOAA Climate.gov

As mentioned previously in the Event Tracker, California is going through one of its wettest water years (October – September) on record. In particular, precipitation so far in 2017 is on a record pace for northern and central California. While the water has been a godsend in reducing and relieving drought conditions, it also has been too much of a good thing as flooding has resulted. One case in particular is the ongoing emergency at the Oroville Dam north of Sacramento. Tremendous amounts of precipitation have led to the Lake Oroville reservoir—the second largest reservoir in the state—to fill past capacity.  The need to funnel water out of the reservoir and accompanying complications has led to flooding concerns and evacuations below the dam.

It has been an amazing turnabout. After a severe and extensive multi-year drought led to extremely low water levels in reservoirs across the state, massive amounts of moisture since the start of the 2016-2017 water year has drastically reversed that trend. At Lake Oroville—a man-made lake that serves as a reservoir for water used by Californians—water levels reached 100% capacity during the beginning of February, nearly 50% higher than is usually seen for this time of year, and threatened to keep rising. That is a problem.


A lot of water has been filtering into Lake Oroville in California in recent weeks, but the climate has served up much higher inflows in the past. The big difference this time appears to be a failure of infrastructure, although the emergency spillways have done their job of preventing a catastrophic failure. Officials remain vigilant, as there is still plenty more rain in the forecast before engineers can go in and completely solve the problem. Events like this are a reminder that in a warming world, in which heavy downpours are expected to increase (IPCC AR5) as greenhouse gases continue to rise, having resilient infrastructure will become even more important.