All eyes are appropriately on Houston right now, where record rainfall has led to catastrophic flooding, loss of life, inestimable damages, and years if not decades of recovery and re-building. Around the country, many communities are now sitting up and paying more attention to that question, “what if that happened here?” Here in Sacramento, where Hurricane Katrina served as a stark warning in 2005 of what can happen when a large storm event overwhelms a flood protection system, the State and local flood protection and maintenance agencies have been hard at work bringing urban levees up to higher standards of protection, consistent with the State’s Central Valley Flood Protection Plan. That Plan was required by Legislation passed in 2007 and paid for by a bond initiative passed by California voters in 2006 – both a clear response to the damage and loss of life in New Orleans due to Hurricane Katrina.

But that Plan is not intended to protect urban areas here from the kind of storm Houston is experiencing, and some would argue it shouldn’t. The cost of protecting communities from that kind of event is astronomical, and as a society with competing needs and too few resources, we have to balance the costs of improving flood protection facilities against the likelihood of events that could breach them. In 2007 the California Legislature set the minimum level of flood protection for urban areas at a level protective of a 200-year flooding event, and the State estimates that bringing urban areas up to that level will cost between $17 and $21 billion over 30 years. That level of protection may not hold up in a 500-year event or a 1000-year event such as Houston is experiencing.

Some have persuasively argued that massive amounts of money should in fact be spent up front to protect communities from the most catastrophic events, in light of the high costs of not being prepared. For example, the United States Geological Survey released a report in 2011 called “Overview of the ARkStorm Scenario.” The report describes a large, scientifically realistic meteorological event in California and analyzes the resulting impacts to property, agriculture, and infrastructure, including the existing flood control system. The hypothetical storm is similar to the intense California winter storms of 1861 and 1862, which were estimated to produce precipitation that in many places would amount to between a 500-year and 1,000-year event. The report is part of a broader project by USGS that aims to engage emergency planners, businesses, universities and government agencies in preparing for major natural disasters.

Not surprisingly, the report concludes that extensive flooding would overwhelm California’s urban flood-protection system, which is aimed primarily at protecting from 100- or 200-year flood events, and California rural flood-protection system, which doesn’t even reach the 100-year event. Under the scenario, the Central Valley experiences hypothetical flooding 300 miles long and 20 or more miles wide. Property damage, primarily from flooding, exceeds $300 billion, and flooding evacuation could involve 1.5 million residents of the Central Valley and Delta areas. Overall losses that could be caused by such a storm are in the range of $725 billion, and the report concludes that such a storm event could produce an “economic catastrophe.”

The report was intended to kick-start a discussion about public policy issues surrounding the risks of such a disaster, primarily related to flood management. As the report suggests, the scenario raises questions about the ability of existing federal, state, and local disaster planners to handle something of this magnitude. The report explicitly raised the policy question of whether it makes sense to pay high costs now to mitigate such an event, or to pay even higher costs later for recovery. In essence, it raises that same question that Dirty Harry posed in the 1971 movie of the same name: “You’ve gotta ask yourself one question: ‘Do I feel lucky?’”

It’s certainly a legitimate question, and the extensive damage in Houston is another reminder that extreme events do happen. But how much the Federal government, states or communities are willing to or can pay to adequately prepare for such events is a legitimate question, one that we expect will be the topic of much discussion over the next few years.