Morris Sheppard Dam: 80 years and counting

The year was 1938. Franklin D. Roosevelt was president. The popular comic superhero, Superman, made his first appearance. Ball Point Pens are introduced. Samsung was formed as a company that sold noodles. And the state of Texas authorized a permit to build a dam on the Brazos River.

That same year, the construction of the Morris Sheppard Dam began. Built in response to disastrous Brazos River flooding, the dam and reservoir were early attempts at water conservation and flood control in Texas.

With the aid of the Works Progress Program, by 1941 the project was complete. Possum Kingdom Lake became the first reservoir built by the Brazos River Reclamation and Conservation District, now the Brazos River Authority. The work was an accumulation of more than a decade of planning efforts to tame a river that historically claimed hundreds of lives with flash flooding and made water supply efforts difficult at best due to periodic extreme drought conditions.

At the time, the Morris Sheppard Dam was the tallest flat-slab buttress dam in the United States.

The dam itself, roughly 60 miles west of Dallas, was an engineering marvel for its time. A design that's continued to stand the test of time. The Morris Sheppard Dam has gates that are unique among the BRA's dams. The gates don't require a mechanical system to raise and lower them. Unlike the newer dams, which can use a remotely operated computer to move the gates, the gates at Morris Sheppard Dam are operated manually using pressure from lake water to help them open and close.

Behind the name

The Morris Sheppard Dam was named after the United States senator who was instrumental in obtaining funding for the project.

Born in 1875 in Wheatville, Morris County, Texas, John Morris Sheppard, the oldest of seven children, was named after an ancestor of his mother's, Robert Morris, who helped finance the American Revolution and signed the Declaration of Independence and the Constitution, according to the Texas State Historical Association.

Sheppard went on to run for Congress in 1902, winning the seat previously held by his recently deceased father. He spent the next 39 years in various elected positions.

Sheppard, who was known as one of the most entertaining public speakers of his era, authored the Eighteenth Amendment to the United States Constitution, which outlawed the production or consumption of alcoholic beverages, and introduced it in the U.S. Senate. As a result, he is commonly referred to as the "father of national Prohibition," according to Sam Houston State University.

Sheppard was instrumental in securing funding to build the dam. Without his support in Washington, the largest reservoir in the Brazos River basin may not have come to fruition. In 1936, the Works Progress Administration in Texas proposed naming the dam after Sheppard. He kindly declined the honor.

In the December 18, 1936 edition of the Stephens County Sun, in an article titled, "Builder Tells of Dam Work: Possum Kingdom Lake Will Be Largest Inland Lake In Texas." Captain H. A. Montgomery, U.S. engineers in charge of building the giant dam, told the Graham Chamber of Commerce, the lake would be the greatest inland lake in Texas, according to the article.

"The Captain explain in detail the work being done and how the dam will serve first as an aid to flood control and then of other uses the water reservoir may be utilized for."

Records show that at the time, engineers estimated the lake would take roughly three years to fill.

But Texas weather would not be predicted.

A very large storm descended on the Lone Star State. The heavy rainfall and runoff, combined with an already wet spring, caused the reservoir to fill within about three weeks. Such was the surprise that cranes from the dams' construction hadn't been entirely removed from the riverbed downstream of the dam when water filled the reservoir, requiring its first-ever release.

Morris Sheppard died in April 1941 from a brain hemorrhage at the age of 65, just days after the Possum Kingdom Lake dam was closed to begin impounding the reservoir. With his sudden death, his family kindly allowed the naming of the 2,700-foot-long and 190-foot-high dam structure in his honor, with a ceremony held in July 1941.

A Different Kind of Power

The Morris Sheppard Dam was originally constructed with a hydroelectric generating facility. On April 17, 1941, runoff had filled the reservoir with sufficient water to begin power generation, and on May 5, 1941, water was discharged, creating hydroelectric power at the reservoir for the first time.

The hydroelectric generating facility consisted of two 11.25-megawatt electric turbine generators and all associated infrastructure. A hydroelectric plant uses energy provided by the weight of water to rotate turbines that generate electricity. Once the stored water is passed through the turbines to generate electricity, it can continue downstream.

Put into service in 1941, the facility ceased power production in 2007 after evaluation by several engineering firms identified safety issues with the electric generating infrastructure. In light of the extensive upgrades necessary to restore the aging facility for future use, the BRA began evaluating the feasibility of maintaining the hydroelectric capability. Ultimately, conducting extensive economic analysis, concluded the required renovation, relicensing, and continued operation of the facility was no longer viable, the BRA Board of Directors voted to apply for decommissioning.

The BRA's surrender of its Federal Energy Regulatory Commission hydroelectric generation license at Possum Kingdom Lake was completed in March 2014. The process required decommissioning of the existing hydroelectric generating facility, which involved nearly three years of construction to permanently disable the plant's hydroelectric functions, and required maintaining the ability to provide for water supply releases from the dam.

During this process, the BRA in 2011 had workers install a conduit, or a large pipe, within the dam structure. This controlled outlet conduit, or COC, allowed the BRA to continue to release water supply once the penstocks to the hydroelectric turbines were removed. When the new conduit was completed, the Brazos River Authority could release a smaller amount of water supply in an easily manageable fashion from the dam without generating electricity or opening a floodgate.

Engineering Marvel

There are four ways water can be released from Morris Sheppard Dam.

All of the release methods work by gravity flow. There is no mechanical or pump capacity to move water through or over the dam. Because of that, each of the release methods are based on lake levels.0 So, if the reservoir is low, less flow will exit the dam.

There are three ways to release smaller amounts of water through the "low flow gates." There is also the uncontrolled spillway, which is a large flat area on the south side of the dam, cut into the rock that would only be used during floods larger than can be released by the nine spillway gates. In the history of Morris Sheppard, such a flood has not occurred, but the facilities are in place if needed.

And then there are, of course, the more well-known bear-trap gates. These nine crest "roof weir" type gates are each about 74 feet long and 13 feet high. Depending on the streamflow and lake elevation, each gate can pass up to 9,600 cubic feet per second of water when open. The measurement cubic foot per second (cfs or ft3/s) is the rate of water movement representing a volume of 1 cubic foot passing a given point during 1 second. This measurement is equivalent to approximately 7.48 gallons per second or 448.8 gallons per minute.

Unlike newer dams that are computer operated, opening a gate at the Morris Sheppard Dam requires physical stealth. An operator must physically climb on top of the gate, attached by a tether above a 190-foot drop, to unlatch a series of locks that secure the gate in the closed position when not in use. Because of this design, each gate can only be operated either fully open or fully closed. These types of gates are rarely used in newer dams because of the manual system.

Maintaining any dam structure requires constant, ongoing care.

As the oldest water supply reservoir in the basin, PK's Morris Sheppard Dam is also the largest of the BRA's System reservoirs.

The maintenance program is rigorous to keep the aging infrastructure in top condition. Rather than contract out every necessary maintenance, repair or improvement project, the BRA has a staff crew dedicated solely to maintaining this enormous structure. The Reservoir System Maintenance Unit, called RSMU, launched in 1992 and has expanded over the past three decades into a vital part of the dam's future.

The RSMU crew works year-round with the knowledge and skillset to do so. RSMU crew members hold a wide variety of skillsets, from operating the barge to move equipment across the water, and using cranes to handle the bigger pieces. These BRA employees are skilled in welding, fabricating, blasting, coatings application, metalizing, and heavy equipment operation, among other skillsets.

In 2021, Possum Kingdom Lake's Morris Sheppard Dam celebrates 80 years from its original completion. And the BRA remains dedicated to extending the service life of this critical water supply reservoir.