Op-Ed: State Agency and University Research Experts Say Dump Desalination Discharge Offshore

This opinion piece was submitted by John Kelly.

The City and their engineers from Freese & Nichols keep referring to the Harte Research Institute study as justification for dumping desalination brine in the bay, yet they haven’t made it available for public review. 

Well the characterization of that and other studies by university and state researchers as a green light for the City’s plan are a serious distortion that undermines everything the City is saying about the environmental impacts. In fact, it’s right up there with Mayor Joe McComb’s argument that desalination will help prevent sea level rise (Yes he really said that.).

So here is the scoop in the form of excerpts from the real science with links to the whole article.

Excerpts From Harte Research Institute (HRI), University of Texas Marine Science Institute (UTMSI), Texas Parks & Wildlife (TPWD) and Texas General Land Office (GLO) Studies on desalination discharge.

Harte Research Institute- Marine Science Literature for Desalinization & Channel Deepening Projects Sunday, 06 September 2020

Link To Exerpts

HRI supports desalination as an option to provide freshwater where it is also beneficial to environmental health, such as relieving pressure on freshwater inflows into bays and estuaries which is vital for their health and productivity.

Several Texas coastal cities and water entities have considered desalination in recent years as a means of supplementing current freshwater resources, but none have developed a functioning large-scale project. Corpus Christi and the Coastal Bend are actively pursuing a viable option.

HRI scientists, led by the late Dr. Wes Tunnell, former Endowed Chair for Biodiversity and Conservation, evaluated several potential locations for desalination intake and discharge for the City of Corpus Christi through a contract with the Freese and Nichols consulting firm. HRI had no input as to locations requested to be evaluated. They were determined by criteria outside the evaluation. Location of water intake and concentrated brine discharge is the single most important way to mitigate environmental concerns.

The HRI report by Stunz and Montagna focused on biophysical impacts of discharge at specified areas designated by the city of Corpus Christi and did not evaluate water quality and contaminant issues. 

Discharge designs and locations must consider the addition of brine concentrate, which can have environmental impacts on the marine community and water quality.  

HRI’s overall and primary conclusion in assessing potential desalination intake and discharge sites in Corpus Christi Bay was that an offshore location of intake and discharge would be the best option to minimize impacts on biota, habitats, and water quality.  

Locations within the bay present many more potential environmental concerns that may not be easily minimized or mitigated. The best available means of minimizing biophysical impacts were provided for each site as part of the evaluation. 

Contaminant water quality concerns were beyond the scope of HRI’s evaluation, but these issues should also be addressed regardless of location. Intake and discharge into offshore waters areas near inlets like Aransas Pass should be avoided for all the reasons noted.

Placement of pipelines to offshore locations from shore locations is a well understood engineering activity, and generally of low environmental risk. Resource and permitting agencies also recognize this and provide guidance to this effect, even expediting permitting outside these sensitive areas. These are summarized in the Marine Seawater Desalination Diversion and Discharge Zones Study as a requirement of House Bill 2031 (84th Legislature).

HRI scientists have almost 200 years of combined expertise relevant to these issues. Institutional Expertise.

Identification and Characterization of Potential Environmental Impacts Mitigation Measures Related to Intake and Discharge Facilities of Seawater Desalination Plants – Dr. Greg Stunz, Endowed Chair for Ocean Health and Fisheries at Harte research Institute and Dr. Paul Montagna, Chair for HydroEcology and Dr. Larry McKinney, Chair for Gulf Strategies.

UTMSI-Desalination Brine Discharge Modeling – Corpus Christi Bay System 

To: Sarah L. Garza, Director of Environmental Planning & Compliance Port of Corpus Christi 

From: Jordan Furnans, PhD, PE, PG LRE Water, LLC Copy Ben R. Hodges, PhD The University of Texas at Austin Date: October 21, 2019

Modeled Bottom Salinity Increase Resulting from Proposed Harbor Island & La Quinta Channel desalination brine discharges, shown for January 5, 2010. Increase is defined as the difference in bottom salinity between models including and excluding the desalination brine discharges. Note: the SUNTANS model does properly simulate the La Quinta Channel discharge due to the coarse model grid in the vicinity of the channel. Figure 19 presents the modeled increase in bottom salinity resulting from the Harbor Island and La Quinta Channel discharges for the date of January 5, 2010. This date represents a time when the modeled discharges would have been occurring for only 5 consecutive days, and is prior to a time when any large freshwater inflow events may affect the computed salinity distribution within the bay system. As shown, bottom salinity increases are near-zero throughout the majority of the bay system. Increases approaching 1 ppt are evident around the La Quinta Channel discharge location and within the La Quinta Channel until the channel’s intersection with the Corpus Christi Ship Channel. This figure does not indicate any increase in bottom salinity in the region surrounding the proposed Harbor Island discharge location.

This model does indicate a 2.5 ppt increase in salinity along and within the La Quinta Channel, yet LRE Water does not believe the current SUNTANS model bathymetry and numerical grid are properly refined to accurately determine the fate and transport of a desalination discharge in this location. It is evident, however, that after a two-year simulation, the modeled La Quinta Channel and Harbor Island discharges are not interacting within each other (Figure 24).

Author’s note: This is an indication of little mixing of tidal and freshwater inflows with this area.

Further model improvements would be necessary, however, to model brine discharges at other locations within the Corpus Christi Bay system, including the La Quinta Channel. Specifically, the model’s triangular grid should be refined to better represent the true width of smaller channels within the system. The model grid would also need to be refined to better represent the island located immediately to the south of the proposed discharge within the La Quinta Channel.

Author’s note: It appears that the closed conditions and lack oftidal and freshwater inflow in La Quinta Channel, which has limited circulation, may result in severe stratification and salinity buildup under certain conditions.

GLO/TPWD- Marine Seawater Desalination Diversion and Discharge Zones Study August 27, 2018

In accordance with TWC Chapter 18., HB 2031 prohibits the diversion of marine seawater and the discharge of wastewater resulting from the desalination of marine seawater in a bay and estuary under the expedited permit process as allowed by TWC Chapter 18. A person has the option to submit an application under TWC Chapter 11 or 26 to seek a permit to divert or discharge in a bay or estuary.  

Author’s note: GLO/TPWD discourages in bay discharge and offers an expedited permitting process for discharges offshore or more.

Source for Scientific links CAPE, http://capetx.com/the-science/