And consider what some other agencies spend. The South Florida Water Management District spends $664 million per year on its operations. The California Department of Water Resources, which operates the state’s dams and canals, spends more than $500 million per year on “public safety and prevention of damages.”
Or compare to road-infrastructure spending: In Houston itself, the public-works budget is $2 billion this year. In California, the state spends $1.9 billion on highway maintenance alone.
Infrastructure is expensive, which is one reason that even an additional $1 trillion would only be a down payment on what the United States needs to maintain its functioning basic systems. But it’s expensive because it serves the needs of whole populations. Multiply anything by 350 million (or 7 million or 1 million) and you get a pretty big number.
In 2016, the Harris County Water District’s former chief estimated that $26 billion would be necessary to really harden the city against flooding. That would be done by, among other things, widening existing channels to increase the throughput of the water-moving machine.
At the same time, however, the city has continued to pave away the land’s natural capacity to absorb rainwater. One study found that over the last four decades, rainfall had increased 26 percent in the Brays Bayou watershed, but “runoff has skyrocketed by 204 percent.”
The city’s human inhabitants must race to protect themselves from ... themselves. The system was designed for a much smaller city with fewer people and much less runoff.
The system was also designed for a Houston climate that featured less extreme rains. The Texas state climatologist John Nielsen-Gammon has shown that rains have gotten more extreme in the city. “Heavy precipitation of any particular magnitude are twice as likely to fall in the Bayou City today as they were in the early 20th century,” the Houston Chronicle reported.
And though improvements to planning and mitigation would be actual improvements, it’s not clear that even a system with a $26 billion upgrade—or more—could have handled what Harvey brought to the area. The 2016 Tax Day Flood dumped 240 billion gallons of water on the county. Already, Harvey has sent 734 billion gallons to the ground in the same area; according to Flood District calculations, there have been 23.7 inches of rainfall on average across the whole county in the 48 hours since the storm made landfall.
Tropical Storm Allison, which struck in 2001, also brought tremendous rainfall, but only a tiny portion of the county crossed 25 inches of precipitation over the five days of that event.
Harvey will be remembered for the breadth of its rainfall, a burden which shows the cracks in Houston’s infrastructure. To survive on the Gulf Coast in the coming century, the city and its surrounding county are going to have to make the kinds of huge investments in flood mitigation that their forbears did after previous disasters.