Allens Creek Reservoir
Frequently Asked Questions
What is the proposed Allens Creek Reservoir?
Allens Creek Reservoir is a proposed water supply storage reservoir planned for construction near the City of Wallis in Austin County. The reservoir is planned to be "off-channel," meaning it will not be built directly on the Brazos River. Instead, it will be constructed just off the Brazos River on Allens Creek, a small tributary of the Brazos. However, water will be pumped into the reservoir from an intake structure on the Brazos River when flow levels are high. Water supply stored in the reservoir will then be available for local and downstream use when flow levels are low by releasing the water back to the Brazos River.
A water right permit to build the reservoir was originally issued to Houston Lighting & Power Company (HL&P – a predecessor of Reliant Energy) in 1974 to provide cooling water for a proposed nuclear power plant. The power plant was not built, and eventually, HL&P allowed the water right permit for the reservoir to expire. Later, the Texas Legislature passed Senate Bill 1593 allowing the Texas Commission on Environmental Quality (TCEQ) to grant a water right for Allens Creek Reservoir to the Texas Water Development Board (TWDB).
The reservoir water right permit was assigned to the Brazos River Authority and its then-partner, the City of Houston, in 2000. The project has essentially been on hold due to the City of Houston’s lack of need for additional water supply. However, as there remains a great need for water by other cities and industries within the Brazos River basin, the BRA purchased the full rights to the Allens Creek project in May 2022.
Where exactly is the Allens Creek property?
The Brazos River Authority owns 9,559 acres located in Austin County west of the Brazos River near the town of Wallis.
What is on the property now?
Most of the land is currently being used for interim agricultural use. There are currently 15 farming and grazing leases amounting to about 8,086 acres. The leases are for a term of one year and generally renew automatically until the land is required for the reservoir.
Who will build the reservoir?
The reservoir will be built and operated by the Brazos River Authority.
How will Allens Creek Reservoir be built?
The project is envisioned to include an earthen embankment dam, spillway structure, low flow outlet works, and an intake and pump station located on the Brazos River.
Why did the Brazos River Authority purchase the full rights to the reservoir from the City of Houston?
The joint agreement between the BRA, the City of Houston and the Texas Water Development Board originated in 2000. At the time of the agreement, it was expected that the City of Houston would require water from the reservoir to meet its growing needs. Since that time, the City has made arrangements for other sources of water supply, and a greater need for water has arisen within the Brazos River basin, specifically in both Brazoria and Fort Bend counties.
What is the projected cost of the reservoir project?
At this time, the total cost is roughly estimated at $500 million. This will be refined as the federal Clean Water Act 404 permitting and engineering design for the project moves forward.
What is the federal Clean Water Act 404 permit?
The reservoir will require permits and authorizations under multiple state and federal regulations including the U.S. Army Corps of Engineers, U.S. Environmental Protection Agency, the U.S. Fish and Wildlife Services, the Texas Commission on Environmental Quality, the Texas Historical Commission, and the Texas Parks and Wildlife Department.
Once studies are complete, the project sponsor may be asked to "mitigate" or find a way to repair or avoid any changes that might be detrimental to the area. Such requirements could be anything from creating more wetland areas to planting trees to moving cemeteries or protecting significant archeological areas.
Will the reservoir include flood control?
No, the reservoir will not serve as a flood control reservoir. However, as part of the permitting process, the BRA must conduct studies to evaluate any impacts that the reservoir may have on flooding. In the event that the reservoir negatively impacts flooding, those impacts must be mitigated or avoided.
When will construction begin?
Construction on the reservoir cannot begin until permitting studies are complete, and permits are obtained and finalized. Below is a projected timeline for the project.
Permitting and Design Phase ~ (5 – 10 years)
- Preliminary Engineering
- Inform Stakeholders/Public
- Conduct extensive analyses and study work
- Apply for and obtain required permits
- Complete final engineering design after the 404 permit is issued
- Construction Phase ~ 4 - 7 years
Will the BRA be required to begin construction by September 1, 2025, as required in the State water right permit?
BRA expects to amend the water rights permit to seek a later construction start date due to the required permitting work that must occur before construction. BRA is not expecting construction to start before 2030.
Will the lake be open for recreation?
The primary purpose of the lake is water supply, however, like many other water supply reservoirs in the State of Texas, recreation is expected to be allowed.
How deep will the reservoir be?
As currently envisioned, the average depth of the reservoir will be approximately 20 feet, as estimated from the United States Geological Survey (USGS) topographic maps for the reservoir. The depth near the dam is expected to be approximately 40 feet.
Once the dam is built, how will the reservoir be filled?
When construction of the reservoir is complete, the Brazos River Authority will be allowed to capture water from both Allens Creek and the Brazos River to begin filling the reservoir. However, the BRA may only divert the flows from both Allens Creek and the Brazos River that are in excess of the needs of the environment and downstream senior water rights.
As an off-channel reservoir, the reservoir will be equipped with pumps that will move water from the Brazos River into Allens Creek Reservoir during times of high flows.
Will Allens Creek continue to flow into the Brazos River?
The proposed Allens Creek Reservoir location lies directly above the confluence of Allens Creek and the Brazos River. A spillway from the reservoir will continue the flow from Allens Creek into the Brazos River.
If there is water in the river that can be pumped out, why build the lake? Why not just pump directly from the river?
The need for water supply does not always match the unpredictable availability of river flows. During drought or times of minimal rainfall, the need for stored water increases. Therefore, the storage of excess water in reservoirs during times of plenty is necessary to deliver water during times of shortage. In this case, water is being pumped from the river when it is available or when the river is flowing in excess of the needs of senior water rights and the environment.
Has a study been conducted to see if flooding/drainage problems at Sealy and Wallis might be corrected and used to fill/maintain the lake?
Flood studies have not been done at this point. However, studies on the impact of flooding around the proposed site will be conducted during the engineering and permitting phase of the project.
This proposed reservoir will flood both documented and undocumented cemeteries. Do you know how many cemeteries will be affected? What will you do with the cemeteries that will be flooded?
A detailed inventory of cemeteries will be performed before constructing the reservoir. Some cemeteries may be relocated. Plans and procedures for possible relocation will be mapped out in the future as the project comes closer to the construction phase.
Are there any archeological sites within the proposed reservoir area?
Initial archeological studies were performed many years ago and indicated the presence of several archeological sites within the proposed reservoir area. Additional investigations will be required to inventory and plan for documentation and possible removal of the sites. This will occur before the final engineering design and construction of the reservoir.