Electricity played a silent part in the growth of Deep Eddy in Eilers Park.

First, when the electricity-producing dam on Lake McDonald broke in 1900, it gave the Swedish Johnson family, which owned the land around Deep Eddy, a chance to replace the lake's recreational losses. Also, in 1902, an electric trolley line stopped at the bathing beach, situated above a rock in the Colorado River that created a dangerous eddy. (The Johnsons dynamited the rock, according to a history written by Hannah Swenson, but the name stuck.)

The Johnsons, who built the nearby house that now serves as the American Legion Post, sold the land to A.J. Eilers, owner of a wholesale goods firm, in 1915. Partnered with a show biz veteran, Eilers built the concrete pool that opened in 1916, one of the oldest in Texas. Nightly movies and rides fit the carnivalesque atmosphere that included a diving horse and a diving child.

Less than a month after Eilers sold the park to the city in 1935, it flooded, destroying all the buildings and filling the pool with debris. The Depression-era bathhouse with its modern roof — once home to the Austin Natural Science Center — was recently reopened to high praise. The spring-fed pool is colder than Barton Springs in the winter, but warmer than the more famous body of water in the summer.