CORPUS CHRISTI, Tx — Two scientists who served on the city's own environmental review committee, along with 11 colleagues they consulted, are warning that the computer model used to assess the proposed Inner Harbor desalination plant cannot answer a fundamental question before the Corpus Christi City Council today: will discharging millions of gallons of salty wastewater into the bay harm it?
Their answer, in a report dated June 1 and obtained by KRIS 6 News: the model cannot tell us.
"Based on the preliminary results presented to date, the modeling exercises have not produced convincing evidence that desalination would not have detrimental ecological effects across the Corpus Christi Bay system," the scientists wrote.
The report was prepared by Dr. Michael Wetz of the Harte Research Institute at TAMUCC and Dr. Sharon Herzka of the University of Texas Marine Science Institute, both of whom sat on the city's Far-Field Modeling Committee. They wrote it in consultation with 11 additional researchers, bringing the total to 13 scientists.
Council votes today on a $78.6 million contract to advance the project to 60 percent design completion.
What is brine and why does it matter?
Desalination removes salt from seawater, leaving behind a byproduct called brine — water far saltier than what went in. The Inner Harbor plant would discharge that brine into the bay.
Saltier water is heavier, so it sinks. When it settles on the bottom and stops mixing with the water above — a process called stratification — oxygen cannot reach the seafloor. The scientists describe what happens next: "Strong and persistent stratification acts as a 'cap' on bottom waters, preventing oxygen replenishment and leading to hypoxic (low oxygen) or anoxic (no oxygen) conditions that are harmful to aquatic life," they wrote.
This is not a new concern for Corpus Christi Bay. "Much prior work has shown that naturally occurring salinity-driven stratification and low-oxygen conditions can occur within 20 cm above the bottom in parts of Corpus Christi Bay," the scientists wrote. Brine discharge, the report states, would make that worse.
What the model found
The city hired Spheros Environmental Group to run the computer model. Spheros found desalination would increase stratification in the ship channel by 2 parts per thousand, and less than 0.5 parts per thousand outside it. Committee member David Loeb told KRIS 6 News the results were encouraging, saying the ship channel is "nowhere near the species highway or the estuary." Fellow committee member Aaron Price disagreed, telling KRIS 6 News: "People have to understand the ship channel is part of the fish highway."
The scientists' report says even those limited results are concerning. In the Inner Harbor, the report states brine discharge would increase bottom-water salinity by up to 2 parts per thousand and "substantially increases stratification and extends it well into the fall and early winter." The worst effects, the report states, would be concentrated at the Viola turning basin, the Inner Harbor's inner reaches.
In the Corpus Christi Ship Channel, the scientists write there is "a moderate to strong increase in stratification," with a dense, salty plume traveling along the bottom at least five miles from the Inner Harbor's mouth. That is significant, the scientists write, because "the Corpus Christi Ship Channel is a primary pathway for dispersal of early life stages of commercially important fish (redfish, spotted seatrout, black drum) and shellfish (blue crab, brown shrimp, white shrimp) species into the Nueces Bay and shallow regions of upper Corpus Christi Bay." The report states the risk period would stretch from summer into fall and early winter.
In Nueces Bay, the model showed limited effects, with most stations showing no change, according to the report. However, the scientists add a caveat that applies to all locations: "the model's limited vertical resolution may obscure differences in salinity and density between the surface and the bottom."
The scientists identify several problems with the model presented to the committee:
The model runs too hot. It overestimates water temperature by 0.92 degrees Celsius in the Inner Harbor and 1.85 degrees Celsius in Nueces Bay, according to the report. Since warm water is less dense, "if the model overestimates temperature, it will underestimate density and stratification compared to real-world data," the scientists wrote.
The vertical resolution was below contract requirements. As of May 21, the number of depth layers in the model was "unacceptably low" and "50% lower than what the contract with Spheros required," the scientists wrote. A test with more layers showed more stratification, suggesting the current model may be underestimating the problem.
Dissolved oxygen was never measured. "Members of the committee repeatedly requested that the dissolved oxygen concentrations be included in the modeling effort," the scientists wrote. Those members were told it was outside the contract's scope. Without it, the scientists write, "the model cannot detect hypoxia caused by stratification, which can lead to serious environmental impacts, including fish kills."
The brine's salinity was never disclosed. "The modelers have also not shared what the salinity of the brine discharge is in the model and this is critical for salinity modeling," the scientists wrote.
The model was never tested against drought. The baseline years — 2023 and 2024 — do not reflect extreme conditions. "2025 was a very dry year, resulting in occasional hypersaline conditions in Nueces Bay. To date, the model has not been validated under such conditions," the scientists wrote.
"At this time, the scientific experts associated with this statement cannot provide a robust and fully informed assessment of how closely the model reflects reality," the scientists wrote.
They say they cannot offer a full environmental assessment until five conditions are met: more time to analyze the model; independent peer review of the model's code and outputs; improved vertical resolution; addition of dissolved oxygen tracking; and extension of the modeling period from two years to 20 to 30 years, to capture "the cumulative effects of discharge and subsequent salinity accumulation."
The city has told the committee the full model report and code "won't be released until the end of June, 2026" — after today's vote. "We encourage the City to provide them to the Far-Field Committee immediately for detailed assessment and to facilitate independent peer review, a standard practice in the scientific community.," the scientists wrote.
The scientists are clear they support desalination, writing that they "recognize the severity of the regional water shortage and the necessity of seawater desalination as a sustainable, drought-proof, long-term freshwater supply solution for residents and industry. Nevertheless, seawater desalination must be performed in a manner that will yield no cumulative negative impact on the bays and estuaries that provide recreational and economic value to the region."
