Waterways in San Antonio

How many stories does your family have that involve water? I'm not talking about the summer of '76 pool story or that time my 4 year-old self slipped in the shower and had to get stitches because I busted my chin wide open, but the stories involving natural water. The water flowing and moving all around us. Most don't pay much mind. But, the rain, rivers, hurricanes and low water crossings make up a surprisingly significant part of my story.

Driving down the road during a thunderstorm, I’ve driven through a puddle that turned out to be about a foot deeper than I thought. My brother-in-law had to be rescued from a car in a low water crossing. I’ve unsuccessfully used a trash bag poncho to keep myself dry driving my Jeep through a storm. When I was in highschool my dad saved a man caught in the floodwaters on Lake Dunlap. I just keep remembering more and more! But why?

It turns out that San Antonio has a lot going on with water. Have you ever noticed when you’re driving northbound on highway 281 after leaving downtown, just past the curves in the road around Trinity and Incarnate Word University, you can see a massive sleek stone structure off to the right? This little section of the road is elevated too. You don’t even really notice until you think about how the tops of the trees are right along the roadway and little glimpses of the basin below peak through. Olmos Basin is one of many strategic locations in town where dams, overflows and rain diverting culverts attempt to subdue the flood waters that barrel through San Antonio. Though you may be tempted to think that these flood and weather events are happening more frequently recently, even the early settlers of San Antonio struggled to cope with our flash flood prone landscape. We have records of mas - sive destructive floods taking out early instructure, homes, and people. Even the location of the Alamo is connected to water. Mission San Antonio was moved to its third, and current location, in 1724 because of flooding caused by a hurricane. Records show that the flooding in 1921 was the cause for new plans to be drafted on the Olmos Dam. Since then, authorities that manage the river have been working to keep San Antonioians out of the rising waters by building dams, water diverting culverts and tunnels that channel the force of water in a better direction. But all this water still flows.

For every inch of rain that falls in San Antonio over half a gallon can be collected from just one square foot of space, and with an average rainfall of 33 inches per year, that is a lot of water. The steep terrain dropping off of the rolling hills of the Edwards Plateau to our northeast, our shallow soils over limestone beds, and narrow creek channels, mean that runoff quickly moves the only way it can: downhill. Olmos Basin sits just behind the Olmos Dam and fills with hundreds of thousands of gallons of water during rain events. Various golf courses, city parks and creeks take the blow during heavy rainfalls, retaining water in holding ponds or send - ing it down the San Antonio and Medina Rivers. Since the birth and growth of San Antonio in the late 1800s homesites, streets, lawns, and parking lots have continued to grow in both size and number. The often impermeable flat surfaces get water flowing and moving and have been adding to our tricky flash flood management. Designers of parking lots and the managers of our rivers build structures that interrupt and divert the sheet flow. Water moves into creeks running between neighborhoods and weaving through parks. Since our rain events often happen suddenly, flash flooding causes water to race through San Antonio. Flood waters can damage property and generally interfere with our daily happenings. Only then do we gripe about the road flooding and low water crossings and notice the pools of water.

Three days later the roads are open, parks are hosting birthday parties and the Riverwalk is alive with tourists. Our daily patterns emerge yet again and an entire dam hides from view. We may take for granted the Riverwalk, Olmos Dam, Salado Creek, Brackenridge Park and so many more well positioned water management systems, but our lives and homes are undoubtedly benefited by their existence.