Houston, founded on a flat coastal prairie, hasn’t always had a problem with flooding. Or, maybe it has always had a problem with flooding. In a city where history is more of a comic book than a textbook, it depends on whom you ask, really. The Houston that we all know today, especially in regards to how it reacts to major floods, was shaped by two catastrophic weather events in the early twentieth century, the first in 1929, the second in 1935.

Houston is, after all, the Bayou City, with 22 waterways, 17 of which are designated as bayous. While a few have been channelized (a technique for altering and straightening the natural waterways with concrete-lined banks), all of Houston’s bayous have an important job: ridding the flat metropolis of its excess rainwater. Despite, or as some argue because of, those concrete canals, the bayous have done an excellent job of preventing flooding. It’s actually the concrete everywhere else that makes us increasingly susceptible to flooding.

Among the many things the City of Houston regulates through construction projects permitting is the coverage of land, specifically how permeable it is. Rainwater can either run off into the storm sewers, which lead to the bayous, or rainwater can seep into the ground. Concrete slabs, sidewalks, and roadways prevent natural absorption, and too much runoff can overtax Houston’s bayous. Unfortunately, this permeability diligence is not practiced far upstream, increasing the chances for floods in suburban neighborhoods that have typically withstood such trials. (Just ask anyone in Meyerland.)

Chief among Houston’s signature, natural waterways is the low and slow-moving Buffalo Bayou, which meanders its way from neighboring Fort Bend County into the western edge of Houston, through its most posh residential neighborhoods, through Memorial Park, into downtown, then splitting industrial Houston on opposite banks, and finally out to Galveston Bay, providing access to the Gulf of Mexico. It’s also our celebrated, but sketchy birthplace, where the Allen brothers dreamt up a future inland port. It’s our connection to nature, while also the mark of our original sin. In the nineteenth century, we embraced it as our first outlet for commerce, forced it into being a navigable waterway, and neglected it with sewage. And in the twentieth century, we arrogantly dredged it deeper and wider. We built way too close to its banks. We even ignored it. Eventually, we fought to clean it up. Today, we celebrate it just as easily as we presume knowing how to control it.

Before Houston became the biggest city in Texas, major floods hurt local interests, especially adjacent to Buffalo Bayou where rainwater runoff takes its time on the low slope to Galveston Bay. But in modern, commercial Houston, “where 17 railroads meet the sea” (per the city’s early motto), catastrophic floods have national economic ramifications. In the early twentieth century, big-time Houston couldn’t afford to lose its hard-won role as one of the nation’s largest ports where lumber, sugar, and rice were shipped worldwide, and where the largest inland cotton market in the world thrived. And nothing, city leaders argued, should jeopardize our oil industry that had set up shop along the 25-foot-deep, 50-mile-long Ship Channel.

A massive flood in 1929 arrived during the drafting of a plan from the newly formed City Planning Commission, which, among other things, recommended dredging all bayous to accelerate runoff. Criticism from land developers meant that little from the plan was actually realized. That April, a storm from the Gulf of Mexico delivered enough rain to submerge bridges along Buffalo Bayou, west of downtown, which itself suffered from extensive damage. The next month, downtown was hit again with as much as 15 inches of rain.

In December 1935, Houston’s largest flood to date claimed 25 blocks downtown and countless residences, and shut down the Port of Houston for months. Floodwaters nearly reached the bottom of the Main Street Viaduct. Despite efforts to protect it, the central water plant failed. Magnolia Brewery, at the corner of Milam and Franklin, famously spanned both banks of Buffalo Bayou. The flood took out most of the multistory building and left only the front door. You can still see the building’s physical remains on the back side of the landmark Magnolia Ballroom. Seven perished in the disaster.

In the wake of these two catastrophic events, fear submerged Houstonians. In response, the Texas legislature established the Harris County Flood Control District, charged with protecting the region from flood damage. In partnership with the City of Houston and US Army Corps of Engineers, HCFCD would execute ambitious capital projects to protect future generations from floods.

Way out west, far from the city limits where Langham Creek, South Mayde Creek, and Buffalo Bayou originated on the Katy Prairie, the US Army Corps of Engineers claimed nearly 13,000 acres. By 1946, they had built two rolled-earth, three-sided reservoirs, over 110 feet tall and 14 miles long, each with a floodgate to control flow into the natural waterways. This flooding protection project was the ultimate not-in-my-backyard solution—so far from the center of town where the majority of us lived downstream, and not requiring any drastic changes to standard building elevations.

And it worked. No one worried. In fact, we felt confident enough to build houses along the wooded banks of Buffalo Bayou, and in 1987, the Wortham Theater opened on a well-known, flood-prone corner of downtown, where a farmers market had stood for decades. In the 1990s, developers began building on those empty lands west of the reservoirs, without any interference from the US Army Corps of Engineers or local county government.

As Greater Houston spread, the doomsday clock began ticking again. To this day, the western sides of the Addicks and Barker Reservoirs are still open—maybe too open, as those barely regulated suburban developments have poured so much concrete on top of the semi-porous soil, preventing pooled rainwater from absorbing and ultimately overtaxing the dams’ walls. Those reservoirs are still working…sort of. In the immediate aftermath of Hurricane Harvey, Houston officials appeared to be on the verge of finding their limits as flood controllers. Early last year, to the relief of beleaguered Meyerland homeowners, a new stormwater detention basin was created where Brays Bayou enters the 610 Loop.

Today, we owe thanks to famed Houston conservationist Terry Hershey, who along with developer George Mitchell and then–US Representative George H. W. Bush prevented the concrete intrusions along Buffalo Bayou, from Shepherd Drive to downtown. Indeed, the most compelling stretches of Houston’s natural waterways can be found where man hasn’t altered the banks in the name of flood prevention, and where wildlife can flourish. East of downtown, Buffalo Bayou Partnership is committed to buying former wharves and industrial sites, and returning them to a natural state—pedestrian bridges, playgrounds, and boat launches are the extent of their visible improvements, and the only concrete they pour is for bike paths.