Update on Future Water Supplies

TCEQ Issues Initial Coastal Bend Desalination Plant Permit

The Texas Commission on Environmental Quality (TCEQ) has granted the first of four permits that would allow the ultimate construction of two seawater desalination facilities serving water customers in the Coastal Bend.  

The City of Corpus Christi, which manages the regional raw water supply system, submitted permit applications in 2020 for two plants, one on the Corpus Christi Inner Harbor and the second on La Quinta Ship Channel in San Patricio County.  Two permits are required for each plant – a water rights permit and a discharge permit.

On October 5, 2022, the TCEQ approved a water rights permit for the Inner Harbor location granting authority to take water from the ship channel.  This authorization, granted without a contested case hearing, marks a major step forward in the methodical process to potentially add seawater as an new, reliable water supply for the region. 


The Board of Directors and Staff of the San Patricio Municipal Water District (SPMWD) are committed to meeting the water needs of our municipal and industrial customers.   The Water District is focused on reliability of the system both in terms of operations and available water supply in order to provide drinking water that meets safety standards and taste expectations and to ensure individual customers’ water needs are met. The South Texas arid region experiences periodic drought conditions that provide challenges to assuring that quantities needed are secure for existing customers and for growth of area communities.

The Water District has constantly encouraged conservation as a key element of our water supply strategy while evaluating additional water supply alternatives.   Beyond working closely with the City of Corpus Christi, the District has regularly investigated other options.


When the 2011-2013 drought was ending, a group of entities began an evaluation of potential new water supplies.  This group, in which the San Patricio Water District participated, initially looked at a range of options including groundwater and desalination.  Members of this water planning group, which included the City of Corpus Christi, members of the Port Industries of Corpus Christi (formerly PICC and now Coastal Bend Industry Association), and the Corpus Christi Regional Economic Development Corporation, contributed the funds to pay for work on a feasibility study.  The Port of Corpus Christi Authority, as a member of the PICC, was also involved. 

The water planning group selected Freese and Nichols, Inc. (FNI) to conduct a desalination feasibility study.  FNI was one of several firms who responded to a request for qualifications to complete the initial feasibility study, and if a project was deemed feasible, to serve as the Owners’ Representative to help with the subsequent work.  The Freese team consisted of recognized global and national experts in water supply and in desalination.   The industrial partners contributed significantly to the project providing managerial and financial acumen and technical water expertise.

After some years of careful analysis and looking at various options, the group determined that improvements in technology and lowered costs now make seawater desalination a feasible and an affordable water alternative to help cushion all regional water customers in a drought.  After evaluating various water supply options, the group focused their analysis on seawater desalination.  Seawater desalination was seen as a viable and valuable addition to our current supply which is solely dependent on surface water which equates to a dependency on rainfall. 

The planning group encouraged the City of Corpus Christi to seek a low interest rate loan from the State Water Infrastructure Fund of Texas (SWIFT) to further develop the project.  In 2018, $2.75 million in funding was secured to further develop the plan.   A methodical approach to siting and permitting was undertaken. More than 19 sites were evaluated using a detailed process with two sites ultimately selected.

Field data was collected over more than a year to supplement existing ecological and water quality data and to assist with the permitting and modeling.  Four permit applications, a water right and water discharge for each of the two plants, were developed and submitted with the intention that both plants will use reverse osmosis desalination technology with diffusers for concentrate discharge water.  The diffusers would mix the discharge with the bay water to ensure that the discharge was close to ambient water salinity once it reached the boundary of the mixing zone.

The effort relied on three guiding principles:

1. The water must be affordable not producing “rate shock” to existing customers;

2. Production of the water must be environmentally responsible; and

3. The project must be reliable.

The plan developed had some key features:

1. Two plants – one on the Inner Harbor and one on La Quinta Channel – could provide a total of 70 million gallons per day (mgd) of water when fully built out.  These plants could use existing transmission/distribution systems to reduce costs for new pipelines and for pumping.  They could be located in areas with relatively high demand. Either, or both, could be sized initially based on need and expanded as need grew.

2. The water produced would become only a part of the overall supply.  Thus, the existing (and less expensive) existing water supplies would help hold down costs and allow for there to be a “blended water” rate.

3. An initial plant, envisioned to be on the Inner Harbor in Corpus Christi west of the Harbor Bridge where demand is the most robust, could be built initially to produce approximately 20 mgd.  It would likely be built to allow for expansion to 30 mgd. 

4. The plant along the La Quinta Channel would be located in the vicinity of the San Patricio Municipal Water District water treatment complex with the intake and discharge on the La Quinta Channel.  It would be sized to 40 mgd for permitting purposes but was envisioned to be constructed when water demands dictated a need.

5. Additional SWIFT funding in the amount of $222,475,000 was secured by the City of Corpus Christi to provide funding for additional work including the construction and initial operation of a 20 mgd seawater plant on the Inner Harbor. 

6. Large volume industrial water customers voluntarily agreed to add 25 cents per 1,000 gallons to the water bills to help with funding of the effort.  This was in addition to the 5 cents per 1,000 gallons paid by all water customers to secure new water supplies.  These monetary contributions did not mean that these large water customers were not subject to the Drought Contingency Plan of the City of Corpus Christi and the SPMWD.    These contributing customers are and would still be subject to curtailments and water use restrictions and penalties in severe drought conditions. In fact, health and safety remain the priority in the allocation of water supplies in severe droughts.


Permit applications were submitted to the TCEQ in early 2020 including a Water Rights  permit (technically called a “Water Use” permit) for each site.  A public meeting on the Inner Harbor permit was held March 2021.  The TCEQ granted the Inner Harbor Water Rights to the City of Corpus Christi in October 2022.  TCEQ issued a draft Water Rights permit for La Quinta in May 2021 and sought public comment but no date has been set for a public meeting on this permit.   Recognizing the workload of the TCEQ staff, the City of Corpus Christi encouraged prioritization of the Inner Harbor permits.

Also in early 2020, two discharge permit applications (technically known as Texas Pollutant Discharge Elimination System, or TPDES,) were also submitted.  These permits require more extensive modeling results to be available before TCEQ staff review can be completed and draft permit applications can be developed.   The modeling information has been submitted and TCEQ review is underway with the Inner Harbor permit being given priority.  No definitive date has been given as to when TCEQ review might be concluded.

One thing of note in terms of the discharge permits, in keeping with the guiding principle that any plant being environmental responsible, the Freese team early in the process developed a white paper on critical dilutions.  This paper asked a primary question – could the plants in our area meet the requirements imposed in California by the US Environmental Protection Agency and the Coastal Commission relative to marine discharge and thus protection of aquatic resources?  (This paper and summary information can be found HERE). 

The answer was YES with use of diffusers being an important part of ensuring responsible environmental operation of the plants.


The San Patricio Municipal Water District is always open to other concepts or sources to strengthen our water supply.  The future of local communities depends on the District being able to supply the water needed at exceptional quality to area residents and businesses.

SPMWD works closely with area communities, District customers, the City of Corpus Christi and others including the Region N Planning Group to encourage water conservation.  Being mindful of ways to wisely use water and decrease water use, not just in times of drought but constantly, is a strategy employed by all of these entities on a daily basis.

(November 2022)