Austin Watershed Protection staffers have stepped away from a proposal to install three gates in the upstream dam of the Barton Springs Pool.
The decision came after pool patrons voiced concerns about potential harm to water quality and the pool’s ecology if the gates were installed, allowing water from the Barton Creek greenbelt to flow into the pool.
A memo from Austin Watershed managing engineer Mike Kelly to the Joint Committee of the Environmental Commission and Parks and Recreation Board in January said the concerns included changes in water temperature and potential increases in the concentration of pollutants and algae.
Under the proposed plan, three gates would have been installed in the upstream dam that could be opened or closed depending on conditions in Barton Creek, including E. coli levels and possible floods.
Installing the gates could have cost up to $1 million and taken between nine and 12 months to finish. The plan was still in its very early stages last fall, and after considering more variables, staff members opted to back away from the proposal until they learned more about the waterway.
“After examining the existing data and information and determining what is needed to make conclusive projections regarding the performance of the gates, staff decided that we are unable at this time to recommend moving forward with the next phase of the gate project,” Kelly wrote.
Barton Springs Pool is fed from underground springs and has an average temperature of 68 to 70 degrees. Except when floodwaters pour over the top of the upstream dam, which happens about four times a year, the pool has been closed off from the creek since city officials installed a bypass tunnel redirecting creek water around the pool in 1975.
Tom Devitt, an Austin Watershed environmental scientist, said the decision to cut the pool off from the creek came before scientists really understood the hydrology of the area and resulted in a body of water that acts more like a pond than a stream.
The pool is home to the Austin blind salamander and the Barton Springs salamander, both endangered species that could be harmed by a change in water conditions.
In addition to the effect on salamanders, swimmers also were concerned about fast-moving water near the dam, pollutants unnecessarily entering the pool and a potential increase in E. coli levels, saying the city has not comprehensively tested upstream waters.
Devitt said water quality in the pool is tested twice each week, but testing upstream of the dam isn’t as frequent.
Kelly said the city needs a more complete understanding of the ecosystem within the pool and how a new inflow of water could change it before further considering the gates.
Watershed Protection will develop a plan for a project to gather that information, which could be included in the department’s project list in 2021. Until then, Barton Springs Pool will remain cut off from the creek.
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