Council approves due diligence and purchase agreement to secure Evangeline groundwater rights; experts outline modeling and monitoring needs

The Corpus Christi City Council voted to move forward with a purchase-and-due-diligence agreement for groundwater rights covering roughly 22,789 acres in San Patricio County that, if transferred, would give the city access to a reported 24 million gallons per day (MGD) of Evangeline aquifer water.

The council authorized staff to complete a 120-day inspection period and a longer due-diligence timeline tied to permit transfers and surface-use agreements; the city agreed to an upfront, nonrefundable earnest payment and an escrow arrangement that would be credited against a final purchase price the council cited in public discussion as about $169.5 million.

Why it matters: Council members and staff described the Evangeline purchase as a fast-moving option to add large, drought‑resistant supply to the city’s portfolio. Hydrogeologists who briefed the council said the San Patricio area holds higher‑quality aquifer sands than many coastal zones, but extracting that water requires careful well design, detailed groundwater flow modeling and long‑term monitoring to avoid subsidence or impacts to nearby domestic wells.

What the council approved: The ordinance before the council authorizes (1) execution of a groundwater-rights purchase-and-sale agreement with Evangeline Laguna LP, (2) an interlocal cooperation agreement with the city of Sinton to allow mutual access and remediation assistance, and (3) an associated resolution authorizing tax‑exempt borrowings to reimburse capital outlays if the purchase closes. Council members voted to approve the package after two hours of presentations and public comment; final closing depends on transfer of drilling and transport permits and on the availability of pre‑negotiated surface‑use agreements with landowners within the tract.

Technical briefing and risks: Enterra geologist Steve Young and Corpus Christi Water interim COO Nick Winkelman walked the council through a multi‑layer conceptual model of the Gulf Coast aquifer system and a site‑specific groundwater flow model being developed for San Patricio and Nueces counties. Young emphasized that the Gulf Coast contains multiple aquifer units separated by clay layers, and that pumping impacts depend on where well screens are placed, the thickness and permeability of local sands, and the presence of confining clays that can delay or magnify pressure changes.

Young summarized field evidence from aquifer tests and geophysical logs (including pilot holes drilled to more than 1,500 feet) showing variable transmissivity: some well test values in the Evangeline area were among the higher ones the team has measured, supporting the feasibility of multi‑MGD well fields. He said earlier pumping tests at two pilot wells produced water quality in the ~800–1,000 mg/L total dissolved solids (TDS) range in targeted intervals, and that arsenic and other contaminants tested near or below drinking‑water standards in initial samples; any measured exceedances would be managed by treatment and operational controls.

On subsidence and neighbor impacts: Young described the nonlinear relationship between drawdown and subsidence in clay‑rich coastal aquifers — clay compaction can be delayed but can occur rapidly once thresholds are reached. He recommended a monitoring network (pressure gauges, GPS/level benchmarks and monitoring wells) and staged pumping protocols to keep water levels within agreed thresholds. Council members repeatedly pressed staff on a neighbor assistance program; staff committed to develop a city‑council‑approved well‑assistance program that would be triggered if private wells are demonstrably affected and to collect baseline well data from neighbors willing to participate before full production begins.

Operations and capacity: Enterra and city staff outlined conceptual well‑field designs for two project areas (referred to at the meeting as eastern and western well fields). Initial recommendations presented to council were roughly 11 MGD sustainable from the eastern field and 17 MGD from the western field under current modeling runs. Staff emphasized these estimates are contingent on continued data collection and model updates; council repeatedly requested that pumping be managed adaptively and that monitoring data be shared with neighbors.

Financial and procedural points: The purchase agreement includes a six‑month due‑diligence/closing window during which Evangeline Laguna is to provide non‑appealable transport and drilling permits and signed surface‑use agreements for well and access infrastructure. Staff said the city will seek reimbursement and long‑term financing through bonds if the deal closes; council also approved a separate reimbursement resolution authorizing the city’s preliminary expenditure and possible subsequent bond financing.

What’s next: Staff will continue engineering and permitting work, complete surveys and title work on parcels, and run further model scenarios that incorporate new well tests and monitoring data. Council members asked for an explicit timeline and for staff to return with details of the proposed neighbor well‑assistance program, thresholds for reduced pumping, and the specific steps the city would take if monitoring indicated unacceptable impacts.

Ending: While council supporters described the Evangeline path as the quickest route to tens of millions of gallons of additional supply, several members warned that the city must couple the purchase with clear monitoring, transparent community outreach and a legally binding program to assist property owners whose wells could be affected.

Speakers quoted (first reference includes full title): "This project gives us a pathway to a substantial new supply — but only if we pair it with strong monitoring and an assistance program," Corpus Christi Water Interim COO Nick Winkelman said. Enterra hydrogeologist Steve Young said, "The aquifer has variable layers; with careful well design we can target deeper sands while minimizing effects on shallow domestic wells." City Manager Peter Zanoni described the purchase agreement as "time‑sensitive" and said staff would return with more detailed financing scenarios.

Votes at a glance: The council approved the groundwater‑rights purchase ordinance and the related reimbursement resolution; both carried on voice votes (outcome recorded: motion carries). Formal closing of the purchase remains conditional on Evangeline Laguna delivering required permits, execution of surface‑use agreements, and completion of title/survey work.