Flooding in Houston's Energy Corridor neighborhood, September 2017. Photo courtesy Revolution Messaging.
There’s an oddity about the way we respond to hurricanes: We rate them by their wind, but their biggest threat usually comes from water.
In fact, a tropical weather system does not even need to hold hurricane status to do devastating damage. The first storm I personally remember – Agnes, in 1972 – was no longer a hurricane when it wandered up the East Coast, crossed over New York City (where I was growing up), and then stalled over the Appalachian hills of northern Pennsylvania and New York state’s “southern tier” of cities from Binghamton to Corning.
Agnes dropped 8 to 12 inches of rain in a wide swath, from Florida’s northeastern Gulf Coast to New York. Some places in Pennsylvania reported nearly 18 inches. Parts of Florida’s Cedar Key were submerged under 7 feet of storm surge. Yet Agnes was only a minimal hurricane when it struck Florida and was in the process of losing its tropical status completely, after being downgraded to a tropical storm, as it approached the Northeast. It was still the costliest storm to that date, and it caused deaths and destruction from the Caribbean to Canada.
In 2001 Tropical Storm Allison dumped almost 3 feet of rain over Houston, causing devastating flooding. Then, in 2017, what had been Hurricane Harvey did virtually the same thing. Harvey got most of its fame from its Category 4 status as it came ashore on the Texas coast; it was the strongest storm to hit the U.S. mainland in a dozen years. But 80% of the deaths it caused in Texas resulted from water, researchers later determined.
As I have written before, the best place to be during a hurricane is someplace else. Coastal residents and people who live in vulnerable structures or flood-prone locations are often advised – and sometimes ordered – to relocate ahead of storms. As I write this, I am looking at the ocean from a Florida barrier beach that is under threat from Tropical Storm Isaias this weekend. Although I would much rather continue isolating at my vacation home during this pandemic, I made contingency plans to get to a hotel room away from the water over the weekend if I need to.
But you can’t evacuate entire cities or river basins. In response to historic floods in the late 19th and early 20th centuries, America developed a reasonably robust flood-control system managed largely by the Army Corps of Engineers. The idea is to protect densely populated downstream cities by capturing and impounding floodwaters behind upstream dams. Engineers can then release the water gradually after the deluge has passed.
The government often purchased homes and land to submerge or remove before completing these dams. This left large, empty – or theoretically empty – catchment basins available to be filled by rising water when necessary. One of my favorite hiking spots is the fields and forests that have grown up behind Vermont’s North Hartland Dam along the Ottauquechee River. The concept behind such emptied basins is that, while creating them inevitably disrupts someone’s life or livelihood, flood control is for the greater good. The same holds true when balancing the environmental consequences of dam-building against dams’ many benefits, which, beyond flood control, include water storage, recreation and power generation.
Downtown Houston is protected by upstream dams that have become part of the sprawling metropolitan area. When Harvey came along, dropping a staggering 60 inches – 5 feet! – of rain on the area, the entire catchment basin filled to overflowing. The Corps was forced to make emergency releases of water in the middle of the night to prevent the Addicks and Barker dams from failing.
The result was a double-sided catastrophe. People died and many properties were damaged below the dams when the released water flooded Houston’s bayous. Yet despite the releases, floodwaters damaged or destroyed thousands of homes and businesses above the dams too. The catchment basin for the dams had not been entirely cleared of development when the dams were built, or kept clear thereafter.
Owners of property behind the dams won a significant victory late last year when Judge Charles Lettow of the U.S. Court of Federal Claims ruled that the Corps is liable for not having cleared the catchment basin. The government declined to acquire surrounding land to keep development from encroaching on the basin over time. This, the court ruled, was a “taking” of the owners’ property, for which the government should have compensated them. While the government argued that Harvey’s unprecedented rain was an unforeseeable natural disaster, Lettow determined that flood-control engineers knew the contours of the vulnerable area in advance.
“[…] the government had made a calculated decision to allow for flooding these lands years before Harvey, when it designed, modified, and maintained the dams in such a way that would flood private properties during severe storms,” Lettow wrote. “Defendant cannot now claim that this harm was unavoidable when it planned for years to impound floodwaters onto plaintiffs’ properties.”
A second phase of the trial, to determine damages, is supposed to begin later this year. The government may appeal.
Downstream property owners have had less success seeking compensation. The same court determined that while the flood control system failed to protect them, this was due to the system’s limitations in the face of Harvey’s record-setting rain. No flood-control system is guaranteed to work 100% of the time, the court ruled. The government is not liable when the task overwhelms the design.
In effect, these two contrary rulings make a distinction between a system whose design was too limited to work – the downstream situation – and a system that worked as designed but failed to protect unsuspecting property owners who were deliberately left in water’s intended storage basin.
The old saying holds that the perfect is the enemy of the good. No flood control system is perfect. Every effort humans make to control nature, or even to divert it from its preferred path, involves trade-offs. Most flood control efforts deprive someone of something they valued. But this is always done – most often justifiably – for the greater good.