Proposed Harbor Island Seawater Reverse Osmosis Desalination Facility

In 2018, the Port of Corpus Christi Authority of Nueces County (POCC) submitted an Industrial Wastewater Permit Application to the Texas Commission on Environmental Quality (TCEQ), which outlines proposed plans to construct a seawater desalination plant capable of generating up to 50 million gallons of potable water per day (MGD) at the former Atofina and Exxon Tank Terminal site on Harbor Island.1, 2 In order to operate at full capacity, models indicate that the offshore intake will need to draw in 150.7 million gallons of raw seawater (with an expected salinity range of 32 – 35 parts per thousand [ppt]) each day, approximately 33.2% (equivalent to 50 MGD) of which will be converted to potable water. The vast majority of the unusable fraction of intake water (approximately 63.4% of the total volume of intake water or the equivalent of 95.5 MGD) will be discharged into the Corpus Christi Shipping Channel (CCSC) daily via a multi-port diffuser. Effluent from the facility (i.e., a mixture of membrane reject and water mechanically extracted from sludge) will contain nearly all of the dissolved and suspended constituents present in raw intake media, including chemical toxicants present as source pollution and additional chemicals added as part of the desalination process.3 The remaining 3.4% of the daily intake water volume (equivalent to 5.1 MGD) will enter a nearby landfill as solid sludge.1, 2 Due to the high productivity and ecological value of the habitat in proximity to the site of the proposed facility, it is imperative that all potential ecological risks be thoroughly evaluated prior to project approval and initiation. The potential risks associated with impingement, entrapment and entrainment of aquatic biota (at the seawater intake site), altered hydrodynamics, changes in the transport and settling of larval fishes, and increasing salinity in the CCSC have been evaluated elsewhere. Therefore, the goal of the present report is to prospectively evaluate the potential ecotoxicological risks associated with discharge of effluent from the proposed facility to the CCSC and surrounding habitat.