so you wanna sample Comanche Springs?

Let’s say, hypothetically, you want to sample Comanche Springs. Here are some quick thoughts about that endeavor.

As the name suggests, Comanche Springs is series of springs that run up Comanche Creek:

After going dry in the late 50s and early 60s, the springs have seasonally returned here and there since the mid-1980s. Over the past decade or so, Big Chief, Koehler’s, and Blue Hole have seasonally returned along with minor seeps that can extend to a hundred feet downstream of the the Church Spring location. Government Spring probably would also be returning if not for a large borehole drilled in its spring basin (probably back in the 1950s when the water control and improvement district was desperate to find water for downspring irrigators).

Koehler’s and Blue Hole springs are seeps with storage (no identifiable feature water emits from and whatever water flows creates a pool of water) and, therefore, probably not the best for sampling. Work this spring on the diversion dam has created a backflow into these two springs as well. That leaves Big Chief Spring located to the side of the present-day pool. Big Chief is located in a locked cage, which has been its fate for an interestingly long time:

I speculate that someone (a kid?) tried to swim into the spring back in the day, got their foot stuck, and drowned resulting in Big Chief’s containment ever since.

Something else to note between the two photographs is the natural pool in the older photograph and the Olympic-ish pool in the recent photograph. As Big Chief and Government springs were failing in the 1950s, the county stepped in to build the Olympic-ish pool inside the natural pool. When they did this, the springs were still flowing, albeit at a lower rate, and nobody knew what their ultimate fate would be. So the Olympic pool was smartly built on stilts to allow the springs to safely flow underneath the pool and into the nearby irrigation canal. This discharge pipe is about 30 inches in diameter and, over the past year, was covered with a grate (theoretically, one could gain access to the underpool by crawling through this pipe.

Flow is about 10 cfs. Relative to the spring, this outlet into the canal is here:

The space under the pool is a bit nasty:

So you may want to sample directly from the spring. You can get access through the local groundwater conservation district, which offices a short walk away from the spring. The flow at 10 cfs appears mellow and not gushy (how’s that for a scientific explanation!). I’ve been there when the flow wasn’t quite high enough to prevent “air gulping” back into (or perhaps out of?) the cave system. Sounded like a poorly balanced washing machine.

Cavers have mapped out part of the cave system for the spring. The system extends some distance to the west toward town and is relatively close to the land surface. Back in the 1950s, as the city’s water well supply was threatened by lower flows, one concern was leaking wastewater infrastructure impacting water quality in the underlying, unconfined aquifer hosting their wells (and the cave system to the springs), something else to consider when sampling (perhaps allowing the system to flush before sampling).