1955 Lewisville Lake Dam on East (Elm) Fork Trinity River upstream of Dallas, TX

(Satellite)

USACE

The USACE completed this dam in 1955 to replace the Lake Dallas Dam. Construction of the Lake Dallas Dam began in 1928 as "the principal source of municipal water for its owner, the city of Dallas." It was 80' (24.4m) high and 11,000' (3.4km) long. This dam is 125' (38m) high and 33,000' (10km) long. "The huge lake that resulted was thirteen miles long, had a 183-mile shoreline and a capacity of 436,000 acre-feet at an elevation of 515 feet, and covered almost one-fifth of Denton County." [tshaonline]

This twdb source has different capacity figures than the above source has. Since the main functions of this dam are water supply and flood control, lake capacities are important.

twdb
The elevation at the top of dam is 560 feet above mean sea level, while the maximum designed water surface is at the elevation of 553 feet above mean sea level. At top of flood control pool (crest of emergency spillway), at an elevation of 532 feet above mean sea level, the lake covers 39,170 acres and stores 989,700 acre feet of water. At the top of the conservation pool, at an elevation of 522 feet above mean sea level, the lake covers 27,175 acres and stores 598,902 acre feet of water.

To add to the confusion, this source says the dam "holds back 2 million acre-feet, or 2.5 billion tons [0.6 trillion gallons], of water when the lake is full."  The normal definition of "full" is the conservation pool, 522'. They must be defining "full" as the maximum designed water surface, 553'. Note that 31' (9.4m) of water would be flowing over the spillway and the water would be within 7' (2.1m) from the top if the reservoir ever got this full.

Fort Worth District, U.S. Army Corps of Engineers posted five photos with the comment: "Construction of the Lewisville Lake dam was completed in August 1955. For more than 70 years the lake has been providing flood risk management for the Lewisville area and downstream communities along with supplying water to neighboring communities and recreational opportunities."

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This is not the spillway. It is the outlet.

YouTube Short

This is the spillway. I had a hard time finding it because it is way off to the side. Probably so that the water will flow over more competent riverbank soil. In fact, looking at a satellite image, under a thin layer of soil is bedrock.

The spillway apron obviously needs repair work. I wonder how many times water has flowed over this spillway. (I looked through past Google Earth images. A few times, and the apron has been torn up and repaired before.)

Google Earth, Jun 2022 (Satellite)

The next Google Earth images shows that they had started much needed repair work on the spillway.

Google Earth, Jun 2023

The latest image available shows that they are still working on it.

Google Earth, Oct 2025

Dec 12, 2015

DallasNews
"Sandbags and tarps have been deployed in an attempt to prevent further erosion of a 160-foot-long slide on the Lewisville Dam. To engineers, the slide’s proximity to another major one that happened in 1995 suggests instability that could threaten the dam’s foundation."
The Dam Called Trouble
[Read the article, there were too many issues for me to summarize. Of note, there was a sand boil and piping during a rainstorm in an area that had leaked for years. Fortunately, the operations team was able to stop the piping by placing "a one-layer ring of sandbags around the sand boil, allowing the pool of water inside to rise about six inches. The method is supposed to equalize the pressure and prevent the water and soil particles from expanding."
Also of particular note, a breech "would submerge downtown Dallas in roughly 50 feet of water, the Corps estimates, causing more than $21 billion in property damage....“It would be a much bigger magnitude to the Dallas area than Hurricane Katrina was to New Orleans,” says Vazquez [The dam's operational manager]."]

$39.1m was awarded in 2019 to improve drain seepage areas. [news_2019] (I wonder what was used for the core for this dam. Or did they not bother to put a cutoff wall in the foundation. More drains sounds like a patch, not a fix.)

$76.1m was awarded in 2022 to repair the spillway. This time they will anchor the apron to the underlying bedrock using post-tensioned anchors. [news_2022]

RED ALERT: bogus AI. If they are going to use AI, I guess it is good that it is really bad so that you know it is AI. The "photo" itself is obviously bogus because many of the diagonal rods don't make sense. But when you compare the "photo" to the real spillway, it becomes absurd.

OceanCraft RC posted

At Lewisville Lake Dam in Texas, engineers are strengthening the spillway by drilling more than 70 high-capacity post-tensioned anchors through the concrete and deep into the underlying bedrock.

The anchors essentially lock the spillway to the rock below, increasing resistance against uplift and sliding when enormous water pressures act beneath the structure during floods.