Watersheds are basin-like landforms defined by highpoints and ridgelines that descend into lower elevations and stream valleys. A watershed, sometimes called a drainage basin or catchment, carries water “shed” from the land after rain falls and snow melts. They consist of surface water–lakes, streams, reservoirs, and wetlands – and all the underlying ground water that may contain many smaller watersheds. Watersheds are important because of the amount of streamflow and the water quality within a river are determined by what happens, human-induced or not, within the them.

Since drainage basins are determined by natural boundaries rather than human determined survey lines, Hays County contains portions of four larger watersheds – Austin-Travis Lakes, Pedernales, Middle Guadalupe, and San Marcos. These are all parts of one even larger watershed, as they all ultimately flow into the Gulf of Mexico at different points. The Pedernales flows into the Colorado River near Lake Travis, and then into the lake itself. The Austin-Travis Lakes flow into the Lower Colorado River, which in turn goes into the Gulf of Mexico at Matagorda Bay. The Middle Guadalupe River has two main tributaries, the Comal and San Marcos Rivers. The Comal flows into the Guadalupe River in New Braunfels, and the San Marcos River joins the Guadalupe near Gonzales. The Middle Guadalupe then continues on toward the coast as the Lower Guadalupe. San Antonio Bay serves as the entry point to the Gulf of Mexico for the Guadalupe.

Within each of the four waterways, there are smaller watersheds. Water that drains off a property into an ephemeral creek (one that flows for a short period of time as a direct response to precipitation), water that drains into a smaller creek, such as Cypress Creek, and water that drains into the larger Blanco River are all examples of the multitudes of internal watersheds within one larger watershed; San Marcos. The Blanco River joins the San Marcos River just east of it’s namesake city in eastern Hays County.

Because the County has only portions of the four watersheds, conditions in surrounding counties which share the watersheds can have important effects in our county. A recent example would be the terrible Memorial Day Flood of 2015 of the Blanco River. A combination of rocky soils, hilly terrain, over-saturated and thin soils and a sudden multiple inch rainfall at the headwaters created a wall of water which came downriver with devastating damage and loss of life along it’s banks.

While there are no natural lakes in Hays County, over the years, lakes and ponds of various sizes in a variety of locations have been built using dams. Some are on private land, some are features in housing developments and some are on the creeks and rivers for public and commercial use. The largest lakes in the area, such as Canyon Lake on the Guadalupe River and Lake Travis on the Colorado River, are not located in Hays County, yet these lakes do impact the county as water sources and for recreational use.

The history of the dams on the Upper San Marcos River gives interesting insight into how humans have interacted with the river over time. During the 1800s, dams were created to impound the flow of the river for agricultural irrigation, power to run saw and grist mills, domestic water supply and production of electricity in limited quantities. Spring Lake was first created in 1849, and a series of dams were built downstream over the ensuing years. Neglect and significant floods have damaged many of these dams, but traces still exist. The Aquarena Springs theme park, located at the site of the springs that are the headwaters of the river, was started in 1924 and became a popular tourist destination on Spring Lake. This park featured an underwater theater complete with a mermaid show, the famous Ralph the Flying Pig, and other fascinating attractions. Today the area is owned by Texas State University and managed as a public education facility known as the Meadows Center for Water and the Environment. Glass bottom boat tours provide observation of the springs and highlight the restoration and conservation activities of the area.

Hays County lakes, rivers and streams are important as indictors of water supply and water quality in the county, and also as major recreational features. Water activities include fishing, tubing, kayaking, canoeing, swimming, and diving. Along the banks, many folks enjoy picnics, bird-watching, plant walks and hiking. Because water is essential to all life and is a finite resource, it is important that we appreciate our water features and treat them with great respect.