After heavy rainfall in recent weeks in drought-stricken California, over 180,000 people were told to evacuate areas near the Oroville Dam, northeast of Sacramento. Officials feared the dam’s spillway may fail, triggering a 30-foot wall of water hurtling into the Feather River, which runs through downtown Oroville. Workers with the California Department of Water Resources are frantically trying to repair the damaged spillway in order to prevent disaster and the evacuation orders were lifted as of Tuesday afternoon due to the progress made so far in reducing the risk of flooding. Yet with storms expected to continue later this week, it is a race against time to fortify the dam’s aging infrastructure. (See timeline of events at Oroville Dam from the blog …& the West.)

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Stanford experts Noah Diffenbaugh and Newsha Ajami spoke about what happened at Oroville Dam and what Californians should expect going forward.

Noah Diffenbaugh is a professor of Earth System Science in the Stanford School of Earth, Energy & Environmental Sciences and the Kimmelman Family Senior Fellow at the Stanford Woods Institute for the Environment.

Newsha Ajami is director of urban water policy at Stanford’s Water in the West Program.

Your lab has done several studies on climate change and the implications for drought and flooding in California. Do recent events bear out the cycles you’ve seen in your research?

Diffenbaugh: What’s happening now is very much in line with our recent research analyzing the historical climate record and projections of future climate change. It’s really an issue of extremes. Right now, we’re having an extremely wet year, on top of a record-breaking five-year drought. The basin upstream of Oroville Dam is at a record 224 percent of normal precipitation, and we are witnessing what happens when so much precipitation falls in such a short amount of time. Our research has shown that global warming doubles the odds of the warm, dry conditions that intensified and extended our recent drought. At the same time, that warming atmosphere carries more water vapor, so you have the potential for more extreme wet periods like this winter.

Our findings also indicate that precipitation is more likely to fall as rain rather than snow, and that the snow that does fall will melt earlier and earlier in the year as global warming continues. That dynamic – which we are already seeing in historical climate observations – has the potential to place additional stress on our reservoirs during intense storm periods. As we are seeing right now at Oroville Dam and elsewhere in California, that kind of stress increases the risk of flooding and landslides, and means that more water is lost as runoff or river flow.

The California Department of Water Resources suspended flows from the Oroville Dam spillway after a concrete section eroded on the middle section of the spillway. (Image credit: Kelly M. Grow / California Department of Water Resources)

Is the situation at Oroville Dam illustrative of greater water infrastructure needs in California?

Ajami: It demonstrates that our aging infrastructure requires better maintenance and upkeep, otherwise it can fail, especially under new climatic realities that are quite different from the historical knowledge used to design and build it. We have to become smarter in the way we manage our water infrastructure system. Using 20th-century tools and governance strategies to manage our existing infrastructure will not meet our 21st-century challenges and needs. We also have to update our water governance tools and strategies at every scale to incorporate today’s climatic realities in our decision-making process and consider innovative solutions that can enable more effective management of our system without any social or economic consequences.

Diffenbaugh: Our dams and other water infrastructure were designed for an old climate that existed 50 or 100 years ago. It is now clear from many lines of evidence that California’s climate has changed, and we are now in a new normal in which more frequent warm, dry, low-snow years are punctuated by wet conditions. The combination of the recent drought and this winter’s storms highlights the need to prepare for risks associated with these extremes.

What should the state or federal governments prioritize in financing water projects?

Ajami: Operation and maintenance of our existing and aging infrastructure should be a priority and not an afterthought. Both the state and federal government should be more proactive in addressing some of the shortcomings and concerns related to infrastructure while considering innovative financing mechanisms to implement water projects, such as recharge ponds, stormwater capture and upper watershed management, that can take the pressure off existing infrastructure networks while adding flexibility to the entire water system. We cannot rely on bonds and special funds – both short-term and temporary solutions – to meet our long-term cost of maintenance needs of our aging infrastructure. They may provide a one-time boost, but we need a more thoughtful strategy to establish sustainable and stable funding sources to meet our needs.

Diffenbaugh: To make up for lost snowpack, we need to improve our ability to recharge groundwater aquifers and fill urban storage facilities with excess runoff. Investing in this type of infrastructure can replenish groundwater that has been drawn down during extreme drought periods while capturing stormwater that we’re currently losing when water runs off of impermeable urban landscapes or is released from reservoirs for flood control. These investments are “win-wins” that will make us more resilient now and in the future.

What is the biggest challenge to increasing investment in our water delivery and flood control systems?

Ajami: While I know my colleagues in the transportation and energy sectors might not fully agree, people are much more willing to pay for the upkeep and maintenance of roads, bridges or energy transmission lines than our water system. This is partly because water is a hidden system and people are disconnected from our complex and sophisticated water network. Most people hardly know where their water comes from or where it goes after use. To change the public’s attitude toward water, we have to do a better job educating the public and demonstrating that reactive responses to our water challenges will end up being costlier than proactive ones. Authorities need a steady fund to maintain the water system and that may mean a change in water rates.

For more information, media are also encouraged to contact Martin McCann, director of the National Performance of Dams Program at Stanford University.