Authored by Gregg A. Eckhardt

Medina Lake was constructed between 1911-1912 as an irrigation reservoir. An extensive canal system delivers water to 34,000 acres of blackland prairie farmlands below the Balcones escarpment around Castroville. At the time it was constructed, it was the biggest irrigation project west of the Mississippi. At spillway capacity, Medina Lake covers about 5,575 acres, has a length of 18 miles, a maximum width of three miles, and 110 miles of shoreline. In addition to the main dam, there is a smaller dam about four miles downstream that creates Diversion Lake, from which discharges are made to the canal system.

Medina Dam, Medina Lake, and Diversion Lake were constructed partially on the Edwards limestone outcrop, so the lakes contribute large amounts of water to Aquifer recharge. Seepage losses from Medina Lake and Diversion Lake have been documented by the USGS and other sources since completion of the irrigation structures in 1912. All of the water lost from the lakes has been assumed to enter the Edwards Aquifer, either directly or indirectly through the Trinity Aquifer. In 2004, the United States Geological Survey completed a water budget analysis and concluded that an average of about 3,083 acre-feet recharges each month (Slattery and Miller, 2004).

A Brief Historical Sketch

In 1910, world famous engineer Dr. Fred Stark Pearson persuaded British investors to finance construction of the Medina dam and canal system. A crew of 1,500 men worked around the clock to mix 292,000 cubic yards of concrete and form it into a waterproof wall 164 feet high, 128 feet wide at the base, 25 feet wide at the top, and 1,580 feet long. Laborers received $2 a day, which were good wages for those days. Most were Mexican nationals who had prior experience building hydroelectric dams with Pearson in Mexico, and most of them brought their families. At least 70 people were killed by accidents and disease during the year of construction.

Medina Lake Dam Construction

Although Dr. Pearson usually gets credit for building Medina Dam, it was not his idea, and several others were instrumental in the project. According to Rev. Cyril Kuehne, who published a historical account of the dam's construction in 1966 called Ripples From Medina Lake, the original dreamer was Castroville founder Henri Castro. The year was around 1850, and means were not available, but Castro assured his fellow pioneers that someday a great dam would be build to harness the Medina River's floodwaters and irrigate the land around Castroville. For decades, pioneers referred to the area that would become Medina Lake as the "Box Canyon". In 1894, Alex Y. Walton was on a hunting trip to the Box Canyon and, upon inspection of the natural contours, became convinced that waters could be held in readiness here and "according to the need for the service of man." He sought expert advice, and obtained enthusiastic support from engineers Terrell Bartlett and Willis Ranney. After completing surveys and engineering plans, they enlisted the help of Judge Duval West to prepare all the legal papers that would be required. Finally, all that was lacking was money, but for years the group was unable to interest anybody who could provide the capital. Discouraged but unwilling to give up, they turned to businessman Thomas B. Palfrey. He was not willing to finance the project himself, but he remembered that Dr. Pearson had employed his friend, a San Antonio native named Clint H. Kearny, and that Kearny had mentioned to him that water power and irrigation sites were becoming scarce in the world, and that if any good prospects were to come to his attention to be sure and let him know. Kearny visited the site and recommended it to Dr. Pearson, who, 16 years after Walton first visited the Box Canyon, finally succeeded in securing financing for construction from British investors.

The pace of construction was frenetic, mostly because the builders expected large floods in the summer of 1913 that would fill the reservoir. The floods never materialized, and after construction was complete in November 1912, it was 18 months before any significant rains occurred. The Lake was not filled to capacity for the first time until September 1919. Whether the designers overestimated the rainfall or the size of the watershed is not clear, but what is certain is the Medina River watershed has simply never been able to supply as much water as they envisioned. Wildly fluctuating levels have characterized Medina Reservoir throughout its entire history.

Medina Dam was only one component of Alex Walton's comprehensive master plan to establish town sites and sell land to prospective farmers. His group established the Medina Irrigation Company and laid out the town of Natalia, named after Pearson's daughter Natalie. But before land sales could be started, world events spelled financial disaster for the project. When England became involved in World War I in 1914, Pearson's access to British capital was limited, and the Company was placed in receivership. In order to make a personal appeal to British investors for more capital, Pearson and his wife boarded the Lusitania and perished when the ocean liner was torpedoed and sunk by a German submarine on May 7, 1915. After that, US federal courts did not allow any land sales, so the Company leased land until it was released from receivership. The stockholders preferred selling the Company to reorganizing, and there were several failed attempts to keep the endeavor alive, but all the subsequent corporations also went into receivership. Finally, in 1950, assets that had cost $6 million to build were sold for $10 and "other valuable considerations" to the Bexar-Medina-Atascosa Counties Water Improvement District No. 1 (BMA), which voters had established in 1925 to oversee the project. The BMA has continued to own and manage the project ever since.

In the 1920s, tourism was all about fresh air and scenery. Tours to the newly constructed dam were a popular diversion for visitors and local residents alike. A hotel-lobby brochure promised "Italian Scenery In Texas" and called Medina Dam "One of the World's Great Engineering Feats". The round trip tour cost $3.50 and took 10 hours, with five hours spent at the dam. The brochure affirmatively declares "the Medina Valley is destined to become the richest spot on the face of the earth in time", and also says:

So stupendous is the conception, so vast the scale of actual accomplishment in the construction of the Medina Dam Project that thousands of its nearest neighbors have positively no conception of the immensity of this undertaking. Yet, by a strange twist of Fate's perversity, this everlasting monument to man's mastery over the greatest forces of nature has achieved a deserved fame in the four corners of the earth, until not only the kings of finance, but royalty itself has leaned forward from its gilded throne and hearkened to the resistless lure of this giant among enterprises.

The huge Impounding Dam, the Diversion Dam, the miles of Reservoirs and Canals, all so aptly fitted into the titanic natural gorge of the Medina River as to make Nature bow to the will of Humanity, combine into a picture at once so enormous and so awe-inspiring that the imagination fails to provide for it a frame, until memory lends its aid. But once seen, this sight can never be forgotten. The first glimpse of the titanic Dam catches the breath in ecstatic surprise, the immense lake of water behind it, stretching for miles, holds one spell-bound. The views in this folder can give but a hint of the many marvels awaiting the visitor.

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