Since 2012 the San Patricio Municipal Water District has been part of a regional effort to evaluate development of seawater desalination plants that will incrementally supplement the Coastal Bend’s water supply.
Early in 2020 the City of Corpus Christi, acting as manager of the regional supply system, submitted permit applications to the Texas Commission on Environmental Quality for two proposed desalination facilities on the shores of the Corpus Christi Bay system. One site is located on the Corpus Christi Ship Channel about one mile west of the Harbor Bridge along the port Inner Harbor. The second location is near the northwest end of La Quinta Ship Channel between Portland and Ingleside on the north shore of Corpus Christi Bay.
Current plans call for the Inner Harbor facility to be built first and for the La Quinta facility in San Patricio County to be built at a later date as demand dictates. The Inner Harbor plant would have a proposed initial capacity to produce an average 20 million gallons per day (MGD). It would be permitted for eventual expansion to 30 MGD.
The La Quinta plant would have an initial production capacity of 20 MGD with essential elements sized for ultimate expansion to a capacity of 40 MGD.
Both plants are expected to produce drinking quality water using reverse osmosis technology. This will allow the water to go directly into the existing potable water distributions system on either side of the bay which will eliminate the need for building a new pipeline system.
Seawater processed at the two plants would come from intake structures on each of the ship channels. Concentrated saltwater exiting the plants will be discharged to the ship channels using jet diffusers at outfalls located near deepwater ship docks some distance away.
An application has been submitted to the Texas Water Development Board seeking a low interest loan to fund design and construction of the Inner Harbor desalination plant. If approved this funding would come from the State Water Implementation Fund for Texas (SWIFT).
The process of identifying the proposed plant sites has been underway since 2018 with funding from an earlier SWIFT loan. During this siting evaluation and permitting phase, lead by consultants Freese and Nichols, more than 19 locations were evaluated in the process leading to selection of the Inner Harbor and La Quinta sites. Primary drivers in site selection were environmental considerations and operating costs.
A COLLABORATIVE EFFORT
Following the South Texas drought of 2011-2013, a planning group was formed to investigate potential sources of uninterruptible water supply for the regional system. This planning effort included participation by the City of Corpus Christi, the San Patricio Municipal Water District, the Port of Corpus Christi Authority, the Corpus Christi Regional Economic Development Corp., and the Port Industries of Corpus Christi (which includes operators of industrial facilities in San Patricio County). The strong consensus of this group was that seawater desalination was feasible for producing additional water for the region that would be drought proof.
The region has spent much of the past decade re-evaluating the regional water supplies and new supply options. Major industrial customers have played a continuing role in the process. In 2018, on a voluntary basis, large volume industrial customers agreed to pay an additional 25 cents per 1,000 gallons. Those funds go to the city’s Long Term Water Supply Fund to help pay for additional water supplies. All customers of the city’s system are paying a surcharge of 5 cents per 1,000 gallons for development of new water supplies.
The Coastal Bend region has a successful history of securing water resources to accommodate future needs. That dates to development of Lake Corpus Christi in the 1950s and Choke Canyon Reservoir in the 1970s. It is evidenced by the coordinated effort to secure long-term water supplies from Lake Texana and water rights in the Lower Colorado River and to construct pipelines to transport water from those sources via the Mary Rhodes Phase I and II Pipelines.
April 2020
