Disregarding local opposition, the City of Austin is conducting a three-year study of an aquifer storage recovery project in Bastrop County on the Carrizo-Wilcox Aquifer.
Local residents voiced concerns that the project could put their drinking water supply at risk of contamination.
Bastrop officials approved a resolution in the spring that underscored the local sentiment, reading, “the proposed ASR project entails significant potential harm to essential groundwater resources and private property rights, and no compensatory benefit to the citizens of the City of Bastrop.”
“I just want to say that all of Bastrop County opposes this project,” Bastrop County Commissioner Butch Carmack of Precinct 1 told the Austin American-Statesman last month.
To mitigate concerns, the City of Austin is allowing Bastrop “stakeholders” a say in the project. However, neither the selection process nor the identities of these stakeholders is publicly disclosed.
Bastrop has undergone significant effort to try to stop this testing.
Residents came together to propose House Bill 1523, which would ensure that the integrity of the aquifer is protected and that local concerns are fully addressed before any project can be authorized.
HB 1523 died in the Senate.
Aquifer Storage Recovery
Aquifers are underground bodies of water, most commonly mixed in with sediment in a slush-like state. They are supplied with water through percolation through permeable layers of land called recharge zones.
This water is constantly moving and flowing, and is an active part of the water cycle. Aquifers supply rivers, lakes, and springs, as well as contribute to evaporation.
Aquifers can be stacked on top of one another and are separated by impermeable layers.
The water table refers to the most shallow aquifer in a specific location, and a characteristic of the water table is depth. Most private wells pump directly from the water table.
Aquifer Storage Recovery (ASR) works by injecting extra water into the aquifer when there is an abundance of resources. When water supplies are low, water is pumped from the aquifer, tested and treated, then delivered to customers.
This method of water storage reduces the amount of water that evaporates when compared to reservoirs, and does not have storage restraints like covered basins.
The City of Austin stated on their website that the “ASR project would make Austin’s water supply more resilient to the effects of climate change and drought and could provide a second source of water during emergencies, like freeze events or flooding.”
ASR is one of the water supply projects included in Austin’s “Water Forward” plan, for water allotting resources during the next 100 years.
The Risks
Water in aquifers typically does not stay in one place.
Yet, ASR will pump treated water directly into the aquifer and it will not be filtered by percolation in recharge zones.
If the water is inadequately treated or if there are any mistakes during treatment processes, the entire aquifer could be contaminated due to the nature of the moving water. This poses a risk to individuals who own private wells that are sourced from the aquifer.
As mentioned in the City of Bastrop’s resolution to support HB 1523, if the injected water is not treated properly, it can introduce harmful pathogens and release undesirable elements like arsenic into the groundwater. Parts of the ASR processes reduce water pressure in the aquifer, “making water access more difficult and costly for surrounding users,” and affecting the local drinking water of thousands.
Also, changes in pressure of aquifers can affect the topography of the surrounding area. When the delicate balance of the groundwater pressure that keeps soil and sediment in place is disturbed too much, sinkholes may occur.
Why Bastrop County?
According to the City of Austin’s website for the project, the area was chosen due to “favorable hydrogeology” and because it “is closer to the existing system infrastructure, and is in an area where water can be stored deep in the aquifer well and below levels of local wells.”
Beyond Bastrop, similar ASR projects were authorized in Williamson and Medina counties by lawmakers this year with Senate Bill 616.
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