Possum Kingdom Lake
From Tardis Wiki, the free Doctor Who reference
The Possum Kingdom Lake was an artificial lake which was located in Texas. The cliff sides of Hell's Gate were near the lake.
In 2565 Prof. Ramirez was leading archaeological expedition at the Possum Kingdom Lake. The lake had dried out and revealed a cave system under the ground. Bernice Summerfield was also taking part at the expedition. (PROSE: Possum Kingdom)