Study links groundwater pumping to subsidence
'Lobby Day' at Capitol slated for March 5
The Giddings Times & News reported last week on recently-documented groundwater contamination from coal ash disposal at sixteen Texas coal-fired power plants.
The old Alcoa Sandow mine at the defunct Sandow Steam Electric Station at Rockdale was one of the sites where unsafe levels of heavy metals, carcinogens and neuro-toxins were found in monitor wells.
Thousands of acres of potentially contaminated property is for sale by Alcoa in Milam, Lee and Bastrop counties, together with billions of gallons of available groundwater rights.
“Whether our state and federal environmental regulators will actually investigate and remediate groundwater at any local disposal sites is a big question”, said Michele Gangnes, a Lee County director of the Simsboro Aquifer Water Defense Fund.
“In contrast, land subsidence has been a hugely expensive fact of life for residents on the Texas coast for many decades. Now a new report tells us we have a high risk for subsidence linked to groundwater pumping locally as well,” she said.
Subsidence in land surfaces is addressed in the state Water Code. Groundwater districts are required to consider the risk of such subsidence from groundwater pumping when they set management goals, issue pumping permits, and set goals for what our aquifers should look like in future.
Currently, the Lost Pines District’s Management Plan concludes that current conditions indicate subsidence from groundwater pumping is not a problem in Lee and Bastrop counties.
Subsidence risk extends beyond coastal regions
The study commissioned by the Texas Water Development Board is intended to help groundwater districts and local stakeholders identify and manage subsidence risks.
The study of major and minor Texas aquifers by LRE Water LLC was presented by TWDB to the House Natural Resources Committee in a hearing last week, and to the board of our local Lost Pines groundwater district in January.
The issue of subsidence risk has also been raised in a pending contested case about LCRA’s mega-permit application at the State Office of Administrative Hearings.
The study refutes the long-held belief that subsidence is an issue only for coastal area aquifers. A TWDB official told the House Committee the study predicts vulnerability to subsidence rather than actually predicting when and to what extent groundwater pumping will cause land to sink.
The computer model developed in the study used data from 340,000 wells. Subsidence risks on a scale of 1 to 10 were assigned to nine major Texas Aquifers.
As a result of the study, TWDB will likely require the Lost Pines District to revisit its conclusions about subsidence locally, because Lee and Bastrop counties have now been found to have a high risk of subsidence from pumping.
Local subsidence risk among highest in state
The Carrizo-Wilcox Aquifer, which runs from northeast Texas to Mexico, was found to be one of five major aquifers at high risk for pumping-related subsidence.
The Simsboro, Calvert Bluff and Hooper formations of the Wilcox Aquifer run under Lee and Bastrop counties, along with the Carrizo Aquifer.
Lost Pines board members were told that in fact, our two counties actually scored a much higher 5.3 risk of future subsidence. In contrast, the Gulf Coast Aquifer’s risk was set at 5.9, the highest subsidence risk of the 9 major aquifers studied.
The local Calvert Bluff and Hooper formations were singled out as having relatively thicker and softer clay soil layers around them. These layers are at greater risk of becoming compressed when groundwater is removed.
The scientist who reported to Lost Pines also included the fact our aquifer formations “communicate” with other formations as an indicator pumping in one formation could affect others.
Sinking coastal areas move from groundwater
The study excluded Harris and Ft. Bend counties’ subsidence districts that have been addressing actual sinking for decades.
The House Committee was told the Houston region has experienced surface subsidence of up 12 feet, with “billions if not trillions of dollars” in related costs. As a result, regulators in the region are mandating a move away from groundwater as a major supply source.
One presenter to the Committee stressed that subsidence is a “one way street” if soils collapse on themselves when aquifers are pumped. Once it occurs, the land does not rebound, and damage to buildings, roads, pipelines and other infrastructure are possible.
The report does not establish the rate at which any region may sink but does provide a “subsidence prediction tool” for use by districts and stakeholders. The tool is intended to help avoid subsidence from occurring in the first place.
Local big pumper denies risk of subsidence
Attorneys for End Op/Recharge, however, disregarded the LRE Water study recently in the LCRA contested case. Citing “many decades of groundwater pumping in [this] region”, they argued there is no evidence to support any claim by local landowners that groundwater pumping poses the risk of subsidence.
End Op also continues to deny that aquifer formations communicate with another, as the Lost Pines District has in the past.
The House committee hearing dwelled on the costs associated with actual subsidence in coastal regions. There was no specific discussion of other aquifers that face both subsidence risk and massive groundwater permits.
Legislature called on to move away from wells
“If granted, LCRA’s 8 billion gallon permit would be added to Recharge, Forestar and Vista Ridge permits to pump another 40 billion gallons out from under us each year,” said Gangnes.
“It is time for our lawmakers to end the water profiteers’ stranglehold on our groundwater. We need to move away from using our groundwater as fuel for growth,” she said.
Rep. Lyle Larson of San Antonio chairs the House Natural Resources Committee and is an outspoken advocate for the San Antonio Water System and its Vista Ridge project in Burleson County.
“Lobby Day” at Capitol
The audience at the Simsboro Aquifer Water Defense Fund meeting last Saturday were told about legislation entitled the “Sustainable Groundwater Development Act” that is being circulated at the Legislature.
The Act seeks to de-emphasize redundant groundwater projects by requiring sustainable, cost-effective, regional projects with multiple sources of water supply.
SAWDF and the League of Independent Voters of Texas are encouraging local residents to participate on March 5th in LIV’s day-long “Lobby Day” at the Capitol that will include visiting lawmakers about the Act.
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