The power of water Why levees don't work, and the challenge of designing them differently

| OPINION

By Kathryn McKenzie

There has been a lot of discussion about why the Pájaro River levee failed, and who’s to blame for the breach that has decimated the Pájaro community. Likely there will be discussion about this for many moons to come. But consider that the ultimate fault may lie with the levee system itself, which has shown over and over to be doomed to failure.

Levees across the United States have been repeatedly broken, breached and overtopped in the past century due to storm action, despite the best efforts of the U.S. Army Corps of Engineers and many other entities. Levee breaks have flooded many communities, often low-income neighborhoods occupied by people of color. Most notably this happened during Hurricane Katrina in New Orleans in 2005, when more than 50 levees and flood walls failed, inundating more than 100,000 homes and businesses and causing months, if not years, of misery for affected residents.

Just after floodwaters hit Pájaro March 10-11, I happened to be reading the book “Water Always Wins: Thriving in an Age of Drought and Deluge,” in which author Erica Gies discusses levees at length. “There are two kinds of levees — those that have failed, and those that are going to fail,” she writes of a rueful joke in the water management community.

Gies points out that Katrina was horrendous, but certainly not the only levee catastrophe in recent history. In 2019, dozens of levees broke on the Mississippi, Missouri and Arkansas rivers following extreme rain and snow events, causing $20 billion in damage and delaying crop planting on millions of acres of farmland.

It’s a simple matter of physics. Levees are basically walls built next to rivers, with the intent of preventing floods. Yes, they stop some flooding, but because the water is contained in a channel, floodwaters run faster and stronger than they would in a natural waterway. When the water does break through, the resulting flood is more forceful and spills out much more water than a natural river might.

Humankind has been building levees since the dawn of civilization, but the system that historically has been used by the U.S. Army Corps of Engineers is a “levees only” engineering strategy. This was adopted in the 19^th century when Americans felt it was their right to bend nature to their will. But as we have found out, water is a force that will ultimately prevail despite our puny efforts.

“In many ways, the story of the levee’s design and failure is a parable about the eternal battle between technology and nature,” wrote Adrienne LaFrance in The Atlantic about the Katrina disaster.

Even in 1949, when the Pájaro River levee was newly built, it was known that the levees-only approach was prone to failure. However, according to a 2019 Scientific American blog article, “each time that skies cloud over and rivers rise, what floodplain residents and their political representatives clamor for is more and bigger levees.”

The other problem with levees — in addition to the fact that they aren’t a be-all and end-all to the problem of flooding — is that the levee system has given us a false sense of security. As decades go by and there are no floods, development takes over in floodplains. It’s all well and good to think your risk is low, until the rains come and it isn’t a hypothetical anymore.

People need to know, though, that living in a floodplain will always carry a risk. There is no absolute guarantee that areas that flooded once will not flood again. The power of water is awesome, and ultimately, it’s going to go where it wants to go.

Local officials need to take a harder look at how to manage building in floodplain areas, and whether there are some places where homes and businesses shouldn’t be built due to repeated previous flooding. Also to be considered are alternate and creative ways of building structures to accommodate occasional flooding, such as putting homes on stilts, or buildings with floating foundations that can rise with the waters.

What is really needed, Gies says in her book, is a new way of thinking about water. Humans must seek to work with it, rather than against it, if we want to keep our infrastructure and ourselves safe and dry.

What would this look like for the Pájaro River? It would take some new thinking about how smart design could alleviate the risk of flooding into populated areas. It could take the form of levee setbacks and creating zones where water can flow when the river level is high, keeping the storm surge from gaining momentum and breaking through the levee downstream. Floodwaters could be safely diverted onto nearby vacant land to eventually sink down and replenish groundwater supplies. Of course, that takes additional planning and funding, and since the river runs through several counties, it’s been difficult to get all parties on the same page. Past efforts for a new levee plan have failed, and that is what has brought us to the current heartbreaking crisis.

The Pájaro River levee is now undergoing emergency repairs, to be followed by long-overdue work by the Army Corps of Engineers. We can only hope that their plan includes some of this fresh thinking about how to manage floodwaters that will inevitably come.

Repair the levees, sure, but also take into account the awesome power of water, which can’t be tamed. But if we acknowledge the reality of water, and the limitations of levees, we stand a chance of protecting Pájaro and other flood-prone communities going into the future.

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