About the Brownsville Pilot
The Brownsville pilot was one of the first seawater desalination facilities in Texas. The pilot was funded with $1.34 million from the TWDB and $500,000 from the Brownsville PUB, which also contributed more than $385,000 in in-kind efforts. The plant was located on the Brownsville Ship Channel on land provided by the Port of Brownsville.
The pilot used a reverse osmosis (RO) process to desalinate water pumped from the channel. The salty water was forced at high pressure through microscopic membranes that filtered the salt from the water. The membranes also filtered out other particles, including bacteria. The "product" (the pure water) was collected; the "concentrate" (or waste) was disposed of in accordance with environmental regulations. Click here for details on the process.
The pilot built on four years of in-depth analyses conducted for the Brownsville PUB with major funding from the TWDB. A feasibility study (30mb .pdf, twdb.state.tx.us) completed in the fall of 2004 determined the technical and economic viability of a demonstration project, identified users for the project, and assessed its costs and benefits. Because of urgent water needs and strong regional support, the Brownsville project was only one of three feasibility studies tapped to proceed to the pilot phase.
The pilot ran for 12 months using various technologies to define the most effective and economical process and select components for a full-scale facility. Results showed that a full-scale seawater desalination plant could be constructed in southern Cameron County. Plans called for sizing the plant to produce 25 million gallons per day, enough to satisfy one third of the total municipal demand projected for the entire county in 2010.
Need for the Project
Population in the Rio Grande Region is projected to more than double over the next 50 years (Fig. 1), fueling increased demand for municipal water supplies (Fig. 2)
The region's primary source of water — the Rio Grande — is overappropriated. Existing supplies from the river are projected to decline more than 25% over next 50 years, due in large part to sedimentation in reservoirs.
The water deficit in the region already exceeds 1 million acre-feet/year, and only half of the demand for water would be met in drought of record. While the biggest impact is on irrigated agriculture, lower volumes severely compromise the ability of irrigation districts to "push" water for municipal deliveries. Meanwhile, the quality of water available to many users continues to degrade, increasing the cost of treatment. (Source: Rio Grande Regional Water Plan 2006, riograndewaterplan.org)
New, local water supply options are limited. Brackish groundwater is being developed, but the extent of such reserves is unknown.
Regional Opportunities
The Rio Grande region is unique in Texas in that it has a well established system of water rights. This provides a perfect mechanism for marketing new water produced through desalination.
The project enjoys widespread regional support, from the Rio Grande Regional Water Authority, the Lower Rio Grande Valley Development Council, and 48 other entities representing communities, irrigation districts, and water suppliers. These stakeholders know that an assured water supply is a must for continued economic growth and quality of life.
Additionally, the City of Laredo and the Brownsville PUB are exploring options to pipe desalinated water upriver to expand municipal and industrial supplies along the middle Rio Grande.
A seawater desalination facility in Brownsville also could provide drinking water source for sister cities in Mexico, thus creating larger economies of scale and reducing unit cost.
Desalination not only will benefit municipal and industrial users; it also will have positive impacts for agricultural users and wildlife. Return flows of desalinated water will indirectly benefit the Rio Grande and some of the surface water now used for municipal purposes could be dedicated to environmental uses.
