The San Antonio River, Headwaters & Olmos Creek

Monday, June 20, 2011

There is a chance of scattered showers forecast for Wednesday; nothing that will break the drought, but the first real chance of rain in over a month. I mention this because today's photos have to do with the ongoing drought and the reality of the water flow in the San Antonio River. I'll discuss this in somewhat more detail after the photos:

Olmos Creek beginning at the downstream side of Olmos Dam

The Blue Hole Spring

The Origin of the San Antonio River (The Headwater)

This is the official origin of the San Antonio River, the headwater, at the confluence of Olmos Creek and the output stream from the Blue Hole Spring.

The San Antonio River dry riverbed looking south from the headwater toward Hildebrand Ave.

When I walked the creek in 2009, there was at least a trickle of water and a few small pools. As can be seen in the photos today, the creek is now powder dry on the surface, although judging from the vegetation growing in the creek bed, there is still enough subsurface moisture to support abundant plant life.

The Blue Hole Spring flows when the Edwards Aquifer level is at or higher than about 670 feet. The aquifer is currently about thirty feet below that level and falling lower almost daily.

The spring flow has been intermittent for the past seventy years or so. As a matter of fact, the spring went dry around 1943 and remained dry for thirty years. Heavy rains in the early 1970's brought the spring back to life in 1973. Water conservation and management of the aquifer have improved in the past four decades, so the time when the the spring flows have increased over the years.

In other words, the headwater of the San Antonio River has frequently dried out. The water flow in the river beginning in Brackenridge Park south of Hildebrand Ave has been maintained since the 1940's, originally by water pumped from wells, but increasingly over the past decade, the San Antonio Water System has discharged recycled water into the river at numerous locations to maintain the water flow.