The Brazos River Basin faces a growing challenge: continuing to provide a reliable water supply for its growing and diverse communities.
And there's a project on the horizon to help ease those growing pains.
The Brazos River Authority's proposed Allens Creek Reservoir project is an off-channel water supply lake aimed at capturing excess water during high flow periods and making it available for use during droughts, ensuring a more sustainable water future for the region.
How will this reservoir, that will hold about 150,000 acre-feet of water, help?
The 11 reservoirs in the BRA Water Supply System within the Brazos River Basin work together to provide water where it's needed. Spanning a vast area comparable to Tennessee, the Brazos River Basin stretches across diverse landscapes in Texas. 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.
So, with only three System reservoirs located on the Brazos River itself (Possum Kingdom Lake, Lake Granbury, and Lake Whitney), there is a lot of water that travels the length of the river uncaptured, flowing into the Gulf.
The proposed Allens Creek Reservoir will help capture some of the water that would have been lost, further enhancing the water supply options for the entire basin. The BRA is in the process of working toward obtaining the required permits to build the planned reservoir in the lower Brazos basin's Austin County between the towns of Sealy and Wallis.
This project will also allow the BRA to more effectively manage the water, said BRA GM/CEO David Collinsworth.
"It'll make the system more drought resilient. It will make our water (operations) more efficient. It will likely allow us to make more water available upstream in Possum Kingdom and Granbury. Even if it didn't generate new water, it's going to be an unbelievable asset to the system approach that we have," Collinsworth said.
Unlike the three water supply reservoirs on the river, Allens Creek will not dam the Brazos River. Instead, it will be an off-channel reservoir located very near the Brazos. Water will be pumped from the river into the lake during periods when the river experiences above-normal flows from rainfall upstream.
However, the BRA may only divert the flows from Allens Creek and the Brazos River that exceed the needs of the environment and downstream senior water rights.
"During different flow regimes of the river, we're going to pump water out of the mainstem of the Brazos, fill Allens Creek, store about 150,000 acre-feet of water, and then the next dry summer that we have, like the last two summers, that will be the reservoir we will release water out of first (to meet downstream supply needs)."
In Texas, to build a reservoir, you must have three things: the property, the water right permit, and a 404 permit from the federal government's U.S. Army Corps of Engineers, he said. The BRA has already secured the first two requirements and will spend the next 5-10 years working to acquire the federal permit. The reservoir will require permits and authorizations under multiple state and federal regulations including, but not limited to, the U.S. Army Corps of Engineers, the U.S. Environmental Protection Agency, the U.S. Fish and Wildlife Service, the Texas Commission on Environmental Quality, the Texas Historical Commission, and the Texas Parks and Wildlife Department.
"It deals with everything from FEMA-related issues to endangered species, impacts on the river, and the river flow," he said. "We're going to put this big, huge package together and send it to the U.S. Army Corps of Engineers. They will then put together their stakeholder group, including many agencies from the state of Texas, U.S. Fish and Wildlife, and the Environmental Protection Agency, which will all get to weigh in on this permit application."
From there, the U.S. Army Corps of Engineers will grant or request changes to the draft permit.
The Bois d'Arc Lake - the newest major reservoir in Texas in over 30 years – required 12 years to achieve their permit, Collinsworth said. The BRA is hoping to move quicker.
"I will tell you right now (if we're able) to start construction in ten years; it will be a huge win for the BRA," he said. "It's a process. It's expensive. It's going to take time. It will still be one of the cheaper water projects in Texas to generate that volume of water."
The proposed Allens Creek Reservoir has been included in Texas' State Water Plan for decades. With population growth across the state expected to increase by 73 percent between 2020 and 2070, the water that this proposed off-channel reservoir will supply is needed to allow portions of the state to continue to help meet the needs of the growing population. And, it will also help to alleviate water supply stress on other basin reservoirs.
Preliminary development work is currently underway for some stream studies and environmental assessment, said BRA Program Manager Randall McCartney.
Moving forward, McCartney said the proposed Allens Creek Reservoir project will be conducted in different phases, including permitting, design, and construction. Allens Creek Reservoir was initially structured as a joint project between the BRA and the city of Houston. The reservoir project has been on hold for quite a while. However, due to the increasing need for water supply in the Brazos River Basin, the BRA purchased full rights to the reservoir from the city of Houston and the Texas Water Development Board in early May 2022, McCartney said.
The proposed Allens Creek Reservoir is expected to provide about 100,000 acre-feet of water per year of firm water supply -- the annual water use of about 260,000 families. At this time, the total cost is roughly estimated at $700 million. The project's projected cost will be refined as the federal Clean Water Act 404 permitting and engineering design process moves forward.
The BRA has made a commitment to this project because the Brazos River Basin needs the water.