City updates Inner Harbor desalination plans after modeling; public voices concern over Baffin Bay and Hillcrest impacts

City staff and the design-build team presented updated modeling results and a demonstration‑plant status report Wednesday as the City of Corpus Christi moves forward with technical work for a proposed Inner Harbor seawater desalination plant.

At a briefing before a packed council chamber, the City’s program management director Brett Van Hazel said the demonstration (pilot) plant is under construction and that the project team will return with a design‑amendment request this month to advance design from roughly 10% to 60% and to develop a guaranteed maximum price. Consultant firms Kiewit (prime), GHD and Freese & Nichols described the modeling work the team used to test diffuser options and to predict whether operations would change water quality at the proposed intake or in the broader Corpus Christi bay system.

The design‑build team showed a new diffuser design that it said increases initial dilution compared with the diffuser concept used for the state permit. GHD’s hydrodynamic modelers said their “near‑field” simulations show the optimized diffuser produces stronger mixing at the point of discharge and that “far‑field” simulations that extend out through the harbor to the intake indicate salinity changes of roughly 1–2.5 practical salinity units (parts per thousand) at the intake location in the worst simulations. Consultants said typical modeled changes farther into Corpus Christi Bay and at the Harbor Bridge were below 0.5 ppt and that the ranges produced by the modeling sit within the historical variability observed in the system.

Kiewit’s presentation said the modeling work used multiple data sources, from port and NOAA bathymetry to ADCP velocity records and long‑term meteorological inputs, and ran multi‑dimensional dispersal calculations on a flexible 3‑D mesh. The team said full report text and the design deliverable (the engineered diffuser and construction documents) will be shared with the council; the consultants noted that raw model code and some proprietary solver inputs are part of the consultant’s intellectual property and not normally published verbatim. Staff said it will produce a public technical summary of findings and that design deliverables and a cost update will be presented to council on July 22 and July 29.

Public comment filled the chamber for more than three hours, with dozens of residents, fishing guides, clergy and community groups urging caution or urging the council to reject discharging desalination brine into local bays. Speakers repeatedly warned that Baffin Bay is a shallow, poorly flushed, hypersaline system; they called it the region’s “speckled trout mecca.” Many residents described long histories of industrial encroachment on predominantly Black…