The earliest years in the history of Mercedes were filled with memorable events and developments.

The city’s name was changed three times in the early 1900s. It started as Capisallo and then Lonsboro before the name of Mercedes was adopted. In that first chapter of city life, fears of Pancho Villa and roving bands of his Villistas crossing the river to wreak havoc led to the U.S. military establishing Camp Llano Grande just outside of town.

The military instillation would later be used to house15,000 soldiers who were being prepared to fight in World War I. Before all of that, there was a major event that occurred right after the city became an official township.

“Mercedes incorporated in 1909, the same year in which itwas inundated by a devastating flood,” states a narrative posted by the Texas State Historical Association.

Ten inches of rain dropped in 24 hours in the newly incorporated city. It was tropical moisture from a 1909 hurricane that cameashore in northeast Mexico, not far from Brownsville with the Rio Grande breaking its banks on July 4. There were no levees, dams or modern flood controls in those days. Communities along or near the Rio Grande – like Mercedes – were at the mercy of the rampaging Rio Grande.

And so began the history of Mercedes with flooding and the means and systems that would be used to deal with such calamities.

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Mercedes Becomes Focal Point

Mercedes, with its central location in the Rio Grande Valley, became the headquarters office of the Lower Rio Grande Floodway Project in1932.

Its operations would manage over 180 miles of river levees, diversion dams and major floodways spanning the RGV from Penitas inwestern Hidalgo County to the Gulf of Mexico. The 1950s would see the establishment of the Mercedes floodway and rail bridge – both of which are still central tothe city – and are engineered to redirect massive volumes of excess floodwater from the Rio Grande.

In the mid-1950s, a monumental project was completed near Zapata with the construction of the Falcon Dam and Reservoir. The joint U.S./Mexico reservoir would dramatically stabilize seasonal river surges and mitigate heavy flooding risks across the entire Valley. It would be tested many times over the years. Its biggest crisis came in September 1967 with Hurricane Beulah and its 20-plus inch rains across South Texas. The volume of water overwhelmed the floodway in Mercedes and sent a devastating wave splashing down the Arroyo Colorado, inundating Harlingen.

It proved to be a sure sign that for as much as had been done when it came to flood control, much more was needed.

Ongoing Colloboration

In 1908, the International Boundary and Water Commission and the U.S. Army Corps of Engineers published a comprehensive Lower Rio Grande Basin, Texas Flood Control Project report.

It would lead to the main floodway going through Mercedes to be structurally re-evaluated and redesigned, along with two other major RGV floodways. Levees near the Rio Grande were raised and rehabilitated, and new networks of outfall ditches and channels were excavated to provide more capacity to divert floodwaters away from growing Valley cities.

Mercedes City Commissioner Ruben Saldana recently wrotein a Facebook report about the sort of collaboration local leaders have with IBWCstaff. He provided information about a recent meeting in Mercedes with the IBWCto discuss the LRGV Flood Control Project. The IBWC operates hundreds of gates along floodways to manage the movement of water. Saldana said the meeting shed important new information for Mercedes.

“We were offered the opportunity to apply for localcontrol of several gates along the floodway in Mercedes,” Saldana wrote. “We arrived at a protocol for the closure of Gate 160 at the Expressway. By closing the gate during major rainfall events, we can...drain and use the floodway to hold stormwater flowing toward us from the West.”

The city of Mercedes and the floodway systems and infrastructure that have emerged over the decades are connected to help avoid the sort of catastrophic flooding that hit the city in its first year of existence over a century ago.

-         Ric Cavazos

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