BRA committee hears early‑work findings for Allens Creek reservoir; alternatives analysis next

The Brazos River Authority’s advisory committee received an update on early‑work studies for the Allens Creek reservoir project on the BRA’s roughly 9,500‑acre site in Austin County, where the authority holds a TCEQ water right to impound up to about 145,000 acre‑feet and a modeled yield near 99,650 acre‑feet. Consultants said those studies have given the team a solid data foundation for the next step: an alternatives analysis that will trade water storage against mitigation and construction cost.

The project team said the March contract for early work focused on boundary and topographic surveys, bathymetry, cultural and environmental field checks and geotechnical investigations. "We were able to get the 2024 raw lidar data from Austin County," Gannett Fleming consultant Scott Birch said, a data set the team validated with more than 100 ground‑truth points and estimated saved about $560,000 versus purchasing new flights. Consultants also reported completing CPT and SPT testing, slug and pump tests, soil and water sampling and installing monitoring wells (the team referenced about 20 wells placed for groundwater monitoring). Laboratory analysis and reporting are ongoing.

Project staff flagged several site features that will affect design and cost: existing oil‑and‑gas pipelines crossing the site, a railroad corridor along State Route 36, and a named wetland called "Alligator Hole" that appears to be connected to Allens Creek. "These are project drivers — the location of pump stations, the wetlands and pipelines — and they will affect mitigation, real‑estate acquisition and cost," said Scott Birch.

Consultants and staff also briefed the committee on land and title considerations. John Dixon, introduced as the Lake Limestone reservoir manager, said when BRA acquired the property in 2000 from Reliant Energy, the seller reserved oil and gas/mineral rights but subordinated surface recovery in practice. The team said no producing wells are currently on the property but that relocation or easements for pipelines will be a cost and schedule factor.

Board members pressed the team on how the reservoir will be filled and whether excavation or on‑site soils will be sufficient to build levees. David (BRA staff) said the design assumes an off‑channel reservoir that will be pumped from the Brazos when flows permit (about 2,200 cubic feet per second or greater at the diversion point). Geotechnical results will determine whether on‑site soils can be used for levee construction or whether fill must be imported, a choice that could materially affect construction cost.

The team also noted programmatic savings and scope adjustments in the early‑work phase: several survey and intake tasks were deferred (estimated at about $385,000) and use of existing county LIDAR avoided a contractual purchase. Presenters said the early work remains on schedule and within the approved early‑work budget.

The committee heard that the City of Houston’s historic involvement and subsequent settlement remain part of project history: representatives said BRA settled a legislative‑mandated transfer of interest with Houston, including a $30 million settlement structure (roughly $15 million paid up front and $15 million contingent on construction). "If we get this permit, we can actually construct it," an authority representative said when summarizing the settlement’s practical effect on moving forward.

What’s next: the team will use the collected data to run an alternatives analysis that weighs pump‑station locations, reservoir footprint and mitigation exposure. That analysis will drive the conceptual designs needed for permitting and for planning the prime construction contract.

The committee adjourned after the update; a formal motion to adjourn was made and seconded and the meeting closed at 12:15 p.m.