Skip to content

Medina Dam at 100

The largest dam in Texas when it was built, Medina Dam celebrates its centennial this year
Written by Rob McCorkle.

The expansive Medina Dam impounds the clear waters of Medina Lake, rising like a gray apparition from the cedar-and-oak scrub clinging to the rugged tumble of hills and canyons 20 miles northwest of San Antonio. Built to harness the mercurial Medina River, this grande dame of Texas dams celebrates its 100th birthday this year.

altIn the early 1900s, naysayers scoffed when ideas began to surface about damming the Medina River at a site known as Box Canyon to provide water to farmers downstream. One critic, Major Clarence Dutton, an engineer by training who commanded the U.S. Arsenal in San Antonio, believed the canyon’s limestone walls were too porous.

“You might as well try to stop a sieve from leaking,” he reportedly told dam booster Alex Walton, a San Antonio civil engineer who first visited Box Canyon on a hunting trip in 1894. A similar idea to dam the river had been proposed half a century earlier by Texas empresario Henri Castro of Alsace, who in the 1840s founded Castroville on the Medina River. According to the Reverend Cyril M. Kuehne’s 1966 historical account, Ripples from Medina Lake, Castro had envisioned the fertile flatlands in the Medina Valley as ideal for farming if waters could be held in the Medina canyon and released “according to the need for the service of man.”

Despite detractors like Dutton, Walton foresaw the establishment of town sites and land that could be sold to prospective farmers. All that was needed was money. After many discussions, Walton finally hit paydirt when he sent word about the proposed project to Dr. Fred Stark Pearson.

Pearson was world-renowned for his development of large-scale, electric-power projects in New York, Boston, Canada, Cuba, Brazil, and Mexico. He deemed the idea feasible and turned to his British financiers, who purchased $6 million in bonds to support the Medina Dam project. Unfortunately, on a subsequent voyage to England in 1915 to solicit additional funds, Pearson and his wife perished aboard the Lusitania when it was sunk by a German torpedo.

When completed in November 1912, the Medina Dam ranked as the state’s largest and the nation’s fourth-largest dam. The concrete behemoth soars 164 feet, stretches 1,600 feet, and impounds 254,000 acre-feet of water at the spillway level.

The Medina Irrigation Company, chartered in 1910, used the influx of British capital to purchase land that would be inundated and to build a main dam about 14 miles north of Castroville and a secondary dam a few miles downriver.

The company contracted with Southern Pacific Railway to build a 19-mile spur from Dunlay to the dam construction site near a huge limestone quarry. Then they began constructing and improving roads from San Antonio, Castroville, and Rio Medina to move equipment and manpower, much of it hauled by mule trains. The dam construction began in November 1911.

A workforce of 3,000, most of them laborers brought from Mexico, toiled for slightly more than a year to complete the dam. Workers poured 300,000 barrels of cement into huge, curved, wooden forms to create interlocking sections set atop and anchored to a thick limestone substrata foundation.

When completed in November 1912, the Medina Dam had cost $1.5 million and rivaled in size Arizona’s Roosevelt Dam, which took three times longer to build. Thousands of acres owned by pioneer ranching families like the Leibolds, Habys, and Seekatzs, as well as the remnants of the Mormon community of Mountain Valley that had existed from 1854 to 1858, disappeared slowly under rising lake waters.

The capriciousness that has come to characterize Medina Lake levels for a century revealed itself at the outset. Heavy rains anticipated in 1913 failed to occur though the lake began to fill. Significant rains finally came 18 months after the dam’s completion. The reservoir finally reached its 254,000 acre-feet capacity in fall 1919.

Today, the Bexar-Medina-Atascosa Counties Water Control and Improvement District No. 1 (BMA) owns and operates the Medina Dam, a smaller diversion dam that impounds Diversion Lake, and the 26 miles of irrigation canals that serve landowners growing various crops on 33,000 acres of farmland.

“The dam works as well today as it did when it was built in 1912,” says BMA’s business manager, Ed Berger. “We’re just completing a $5.6 million stabilization project, the dam’s first major modification.”

Ringed by a handful of communities, ranches, marinas, and other commercial businesses, Medina Lake has come to be recognized not only as a recreational destination for boaters and anglers, but also as a valuable source of recharge for the Edwards Aquifer, which supplies part of San Antonio’s drinking water.

“Most people don’t realize that Medina Lake was the only lake in this part of Texas for many years until Canyon Lake was built in the ’60s,”says Carol L. Smith, executive director of the Medina Lake Preservation Society.

“When Medina Lake was being constructed, there was a gravel toll road (built by an industrious landowner) leading from FM 471 to the construction site. Sightseers from San Antonio would travel up FM 471 in Packard touring cars and stop at a little rock house at the intersection, where a monkey wearing a tiny hat would come out and collect the tolls. The toll road was eventually paved and became FM 1283.”

Medina Lake’s romantic era of toll-collecting monkeys has faded, but the Bedrock Resort overlooking the Medina Dam on the lake’s south shore stands as a reminder. Built in 1913 and now owned by Roxanne and Steve Bonahoom, the resort survives as one of the few remaining sites from Medina Lake’s heyday.

Three historical markers currently stand atop the dam: one denoting the Mormon community that once existed 12 miles upriver, a second recalling the dam’s history, and a third recognizing Medina Dam as a Texas civil engineering landmark. Because of U.S. Department of Homeland Security regulations that now prohibit public access to the dam, plans call for the markers to be moved to a site near the entrance where they will be on view.

No doubt, European immigrant Henri Castro would be proud to know his dream of harnessing the Medina River for man’s use proved prophetic, thanks, in part, to British money, Mexican labor, and American perseverance and ingenuity. 

For more information on the Medina Dam Centennial Celebration, check out the TH Essentials


Back to top