Bayou City Waterkeeper and our partners are urging state regulators to deny or delay a proposed permit for concentrated brine discharge into Galveston Bay.
As Texas searches for new sources of water, seawater desalination is receiving increased attention. But producing freshwater from saltwater creates another challenge: what happens to the highly concentrated saltwater left behind?
A proposed seawater desalination facility in Bacliff would discharge that concentrated brine into Galveston Bay. On August 21, Bayou City Waterkeeper joined Galveston Bay Foundation and the Sierra Club Lone Star Chapter in urging the Texas Commission on Environmental Quality to deny proposed Permit No. WQ0005502000—or, at minimum, defer its decision until the applicant provides stronger evidence that the discharge will protect water quality and aquatic life.
The permit application relies on computer modeling to predict how the brine would move and mix with the Bay. Independent experts who reviewed that modeling found significant shortcomings, raising concerns that regulators do not yet have the information they need to understand the project’s potential effects.
“This permit asks the public to accept serious risks to Galveston Bay without requiring the applicant to demonstrate that its modeling reflects what could happen in the water,” said Rachel Jordan, staff attorney at Bayou City Waterkeeper. “TCEQ should not approve the discharge unless the applicant can show, through reliable modeling and field data, that it will comply with water-quality standards and protect aquatic life.”
Why brine is different from ordinary saltwater
Desalination plants remove salt and other minerals from seawater to produce water that can be used by people, industries, or utilities. That process leaves behind brine with a higher salt concentration than the water taken into the facility.
Because concentrated brine is denser than the surrounding Bay water, it can sink and spread along the bottom. If it does not disperse quickly enough, it may form a distinct layer that prevents oxygen from circulating into deeper water, a process known as stratification. That can contribute to hypoxia, or dangerously low dissolved-oxygen levels, threatening fish, shellfish, and other organisms.
That possibility is especially concerning in a shallow, semi-enclosed estuary such as Galveston Bay. The Bay is already under pressure from industrial activity, development, climate change, and changing freshwater inflows. Before another significant discharge is authorized, the applicant must credibly demonstrate how the brine will behave during the conditions when the Bay could be most vulnerable.
The current models may make the brine disappear too quickly
Two independent experts identified weaknesses in the analyses submitted in support of the facility.
Dr. Ben Hodges, an inland and coastal water-modeling scientist, found that the models may artificially mix the brine into the surrounding water faster than it would disperse in Galveston Bay.
This problem, known as “numerical diffusion,” can occur when a model divides the water column into layers that are too thick to represent a thin plume moving along the bottom. In effect, the simulation may blend the dense brine with a much larger volume of water as soon as it is discharged, showing the plume becoming diluted and disappearing even if it could remain concentrated near the Bay floor.
Hodges found that the models lack sufficient vertical resolution and have not been tested on progressively finer grids to demonstrate that they can accurately represent how long the plume could persist, making the current analyses insufficient to reliably determine whether the discharge would create near-bottom stratification and possible hypoxia.
A separate review by Dr. Arnoldo Valle-Levinson identified additional concerns. According to the coalition’s comments, the model did not reliably reproduce observed salinity conditions and performed worst during dry periods, when Galveston Bay may be especially vulnerable. His review also raised questions about how it accounts for tides, circulation, flushing, turbulence, sea-level trends, and long-term variability.
Together, these reviews raise doubts about whether TCEQ has a reliable picture of how the proposed discharge could affect Galveston Bay.
“If the assumptions, data inputs, or geographic scope of that modeling are incomplete or unrealistic, the results may understate the project’s actual effects,” said Jacob Hupp, Government Affairs and Public Policy Manager at Galveston Bay Foundation. “That creates a risk that TCEQ could conclude the discharge is protective of water quality and aquatic life without having a full picture of the consequences for sensitive areas, fisheries, wetlands, wildlife, and nearby communities.”
Computer models need real-world measurements
Improving the model alone would not resolve every concern. Hodges also found that the applicant lacks field studies measuring the mixing energy near the Bay bottom where the plume would spread.
Winds, waves, tides, currents, and other forces may provide enough energy to disperse the brine before it creates low-oxygen conditions. But without measuring those conditions in the proposed discharge area, there is no reliable way to confirm that the model represents what happens in the Bay.
These measurements can be collected before the facility begins operating. Hodges recommends that a qualified, independent third party conduct field studies of the ambient mixing energy near the bottom and compare those results with the model’s predictions.
This is not an argument that every desalination project will necessarily cause hypoxia. It is an argument that regulators should not assume the risk is negligible when the necessary modeling and field evidence are missing.
The permit also lacks enforceable salinity protections
Even reliable modeling would only predict how the brine may behave. The permit itself must contain safeguards that can be enforced once the facility begins operating.
“Despite seawater desalination being actively pursued as a new water supply strategy for Texas, we still don’t have a clear mechanism in place to protect salinity levels in our bays and estuaries,” said Evgenia Spears, Water Program Manager at the Sierra Club Lone Star Chapter. “The current standards for salinity are vague, and as written, not really enforceable. And while modeling is important, as it can give us a good idea of how brine discharges are likely to behave, a model is still a prediction and by itself isn’t a water quality standard.”
The proposed permit does not establish enforceable limits on discharge salinity or require ongoing monitoring sufficient to determine how the discharge affects conditions in Galveston Bay. Without those requirements, regulators and the public would have no dependable way to confirm that actual conditions match the assumptions used to approve the project.
Other desalination permits in Texas, California, and abroad limit how much a discharge may increase salinity above surrounding conditions. Bayou City Waterkeeper and our partners are calling for comparable protections here, including monitoring at appropriate locations and depths near and beyond the outfall.
Those protections will become increasingly important as more desalination facilities are proposed along the Texas coast. Regulators must be able to evaluate not only each individual discharge but also the cumulative effects of multiple projects on bays and estuaries over time.
“The lack of stringent salinity standards, given the level of interest in seawater desalination, is a major regulatory gap in Texas,” Spears said.
We are also asking TCEQ to determine whether the plant should be classified as a major facility, which would carry more rigorous oversight and reporting requirements. We are asking the applicant to complete the federal rating worksheet and for the TCEQ to make its determination public before acting on the permit.
Galveston Bay should not be treated as a testing ground
The proposed facility would locate both its seawater intake and brine discharge inside Galveston Bay. If seawater desalination moves forward in this region, our comments argue that the state should consider intake and discharge locations in the Gulf of Mexico, within zones previously recommended by the Texas General Land Office and Texas Parks and Wildlife Department.
Locating the intake and outfall outside the Bay would not eliminate every environmental concern associated with desalination. It would, however, avoid introducing concentrated brine into a shallow estuary that supports vital habitat, commercial and recreational fisheries, and communities whose lives and livelihoods are connected to the water.
“Texas’s search for new water supplies cannot come at the expense of the bays and communities those projects are supposed to sustain,” said Guadalupe Fernández, Policy Strategy Director of Bayou City Waterkeeper. “Galveston Bay is not an empty basin for industrial discharges. It is a living system, and decisions about its future must reflect the cumulative pressures it already carries.”
What we are asking TCEQ to do
Bayou City Waterkeeper, Galveston Bay Foundation, and the Sierra Club Lone Star Chapter are asking TCEQ to deny the permit or defer its decision until the applicant:
- Provides complete, independently reviewable modeling that can reliably evaluate salinity, currents, stratification, flushing, and dissolved oxygen;
- Evaluates conditions during dry periods, low flows, tidal changes, and long-term environmental change;
- Conducts field studies of the mixing energy near the Bay bottom;
- Demonstrates that the discharge will not create harmful stratification, hypoxia, or other violations of Texas water-quality standards;
- Completes the required evaluation of whether the plant should be regulated as a major facility; and
- Accepts enforceable salinity limits and ongoing monitoring requirements.
We have also requested a public meeting so affected community members can learn more about the proposal, ask questions, and formally submit their concerns.
Texas does not need to choose between preparing for future water needs and protecting Galveston Bay. But it does need decisions grounded in credible science, enforceable safeguards, and meaningful public participation. Until those protections are in place, approving this discharge would be premature.
View our comments in full.
For questions about our wetlands protection and Ship Channel advocacy please reach out to kristen@bayoucitywaterkeeper.org and rachel@bayoucitywaterkeeper.org.