How we know this: read on 2026-09-21 — the Cameron County Regional Mobility Authority’s SPI 2nd Access project page and its July 2026 project presentation (PDF), TxDOT’s own South Padre Island Second Access project site, and two Port Isabel–South Padre Press reports: the 3 September 2026 piece marking 25 years since the Queen Isabella Causeway collapse, and the 30 April 2026 report on the RGV-Desal announcement. Left out for want of a source: the “$700 million to $1 billion” cost range for SH 104, an “11-mile” corridor length (the agency says 17.6 miles), the FM 106 / FM 510-to-north-island alignment, deck-runoff capture systems, seagrass and ocelot mitigation specifics, a late-2026 federal clearance date and 2029–2032 construction window, and the claim that the desalination venture has bought land on the north end of the Island — none of that appears on any page we could fetch.
One road on and off the Island
The Queen Isabella Memorial Causeway — State Highway 100 — is the only roadway connection to and from South Padre Island. Both TxDOT and the Cameron County Regional Mobility Authority say so in the same plain terms, and both give the same reason for studying a second crossing: a single connection “causes mobility and safety challenges during emergency evacuations.” TxDOT states the project’s purpose is to explore alternate connections between the Texas mainland and South Padre Island that improve mobility and enhance public safety during emergency evacuations.
Twenty-five years since the collapse
The reason that single-corridor risk is not an abstraction here: in the early morning hours of 15 September 2001, the towboat Brown Water V, pushing four barges, collided with the Queen Isabella Causeway.
According to National Transportation Safety Board records cited by the Port Isabel–South Padre Press, two sections of the causeway totalling approximately 160 feet collapsed after the collision. Ten passenger vehicles either fell with the collapsing sections or drove off the remaining roadway. Eight people died. A third section collapsed later the same day. Three people survived: Brigette Goza of Port Isabel, Rene Mata of Laguna Vista and Gustavo Morales Jr. of Brownsville. The causeway was repaired and reopened on 21 November 2001 — just over two months of the Island being cut off by road.
Port Isabel held a 25th Anniversary Remembrance on 15 September 2026 at the Port Isabel Event & Cultural Center, with a Coast Guard color guard, a speaker panel and a screening of a TxDOT documentary on the collapse and its aftermath.
State Highway 104: what is actually on the books
The second crossing has a formal identity. CCRMA lists it as the South Padre Island Second Access Project, State Highway (SH) 104, CSJ 0775-02-002. An environmental study is currently underway, led by TxDOT in collaboration with CCRMA, exploring alternate non-tolled connections from the Texas mainland, across the Laguna Madre, to South Padre Island.
The project’s recent history, as CCRMA records it:
- It was placed on hold in December 2017.
- On 12 December 2023 the Texas Transportation Commission approved its on-system designation through Minute Order 116614.
- TxDOT is now the project sponsor and is preparing a Supplemental Draft Environmental Impact Statement, as a non-tolled project.
- A public information workshop was held on 6 November 2025, with a virtual option posted online.
CCRMA’s July 2026 project presentation gives the physical scale: the project “will include a bridge approximately 8 miles long as well as improvements to roadways on the mainland and on the Island,” and “the total length of the SH 104 Project is approximately 17.6 miles.” The same presentation reports preliminary engineering at 98% complete, with environmental work and right-of-way and utilities both “underway,” and lists the remaining needs as completing the Supplemental EIS, design and funding.
What those documents do not give is a price tag, a chosen alignment or a construction start date. For scale: the Island stretches about 34 miles from the Port Mansfield Channel to Brazos Santiago Pass, and the city sits roughly eight miles north of the Mexican border. If you want to follow the environmental study, TxDOT keeps a project site with a study-area map and an email and SMS subscription list.
A 50-million-gallon-a-day desalination plant, separately
A second large project would touch the region’s water rather than its roads, and it is a private venture, not a public works programme.
As the Port Isabel–South Padre Press reported on 30 April 2026, US Desalination LLC and IDE Technologies announced the formation of RGV-Desal, LLC, a joint venture that will design, develop and operate a 50-million-gallon-per-day marine desalination facility. The plant is planned along the Gulf Coast near South Padre Island and would convert seawater into drinking water using advanced reverse osmosis. It is expected to cost around $1 billion and to be privately funded through the RGV-Desal partnership.
Project leaders say the facility would provide a supplemental water source for both public utilities and industrial users across the Valley, reducing reliance on the Rio Grande and on strained groundwater supplies. “The formation of RGV-Desal is a defining moment for water infrastructure in South Texas,” said Sean Strawbridge, chairman of the board of US Desalination. “This is exactly the kind of bold, market-driven infrastructure investment that will ensure the Rio Grande Valley can support its growing communities and economy for generations to come.”
The announcement lands against real pressure on the river: studies have found more than half of the water used in the Rio Grande basin is being depleted faster than it can naturally be replenished. No specific site, permit status or construction schedule appears in the report we read — so treat the plant as announced, not as under construction.
Sources
- Cameron County Regional Mobility Authority — SPI 2nd Access — the SH 104 designation and CSJ number, the TxDOT-led non-tolled environmental study across the Laguna Madre, the December 2017 hold, Minute Order 116614 of 12 December 2023, TxDOT as project sponsor preparing a Supplemental Draft EIS, the 6 November 2025 workshop, the Queen Isabella Causeway as SH 100 and sole roadway connection, and the Island’s 34-mile length.
- CCRMA Project Presentation, July 2026 (PDF) — the approximately 8-mile bridge, the approximately 17.6-mile total project length, preliminary engineering at 98%, and the remaining project needs.
- TxDOT — South Padre Island Second Access Project — the project overview, the non-tolled framing, and the stated purpose regarding evacuation mobility and public safety.
- Port Isabel–South Padre Press, “Causeway collapse remembered 25 years later” (3 September 2026) — the 15 September 2001 allision by the towboat Brown Water V pushing four barges, the two collapsed sections totalling about 160 feet, ten vehicles, eight deaths, the third section, the three survivors, the 21 November 2001 reopening, and the 2026 remembrance event.
- Port Isabel–South Padre Press, “Major desalination plant planned on SPI” (30 April 2026) — the RGV-Desal, LLC joint venture between US Desalination LLC and IDE Technologies, the 50 MGD marine reverse-osmosis facility planned along the Gulf Coast near South Padre Island, the roughly $1 billion privately funded cost, the stated purpose, the Strawbridge quotation, and the Rio Grande basin depletion finding.