The San Jacinto River Authority is leading a two-part study—the San Jacinto River Flood Protection Project—that focuses on Lake Conroe and Spring Creek. The first phase of the study—which began in February 2017—examines the flood plains near Lake Conroe, while the second phase of the study—which has not yet begun—will determine a potential site for a reservoir near Spring Creek and study how releases from Lake Conroe affect the surrounding areas.
The SJRA is also one of the partners on a regional study led by the Harris County Flood Control District that will examine more than 500 miles of streams that flow into the San Jacinto River. Dena Green, HCFCD feasibility studies department manager, said one of the goals of the study—the Upper San Jacinto River Regional Watershed Flood Mitigation Plan—is to develop projects that could be implemented to reduce flooding in the area covered in the study.
“We’re looking for kind of large-scale projects that could help broad areas, so we’re talking about regional projects,” Green said. “It might be a section of channel conveyance improvements or a large detention basin.”
A regional approach
HCFCD’s study will examine 13 different major channels and tributaries that flow into the San Jacinto River between I-10 in Houston and Hwy. 30 near Huntsville. Green said it is important to take a broad, regional approach to this study because of the amount of water these channels carry into the San Jacinto River and Lake Houston.
“In order to be able to have a complete picture of the drainage characteristics and behaviors of the San Jacinto River watershed, we do need to look at it and its system as a whole,” Green said.
The study has numerous objectives, Green said. One priority includes evaluating all streams that flow into the San Jacinto River to develop consistent information regarding the flood risks along each channel. In addition, the study will identify new communication protocols for the different agencies in the study area—such as the Harris County Office of Emergency Management, the Montgomery County Office of Emergency and the SJRA—to follow in a flooding event.
Finally, the study will develop a comprehensive list of future major projects that could prevent flooding in the study area, such as improving channel conveyance or building a regional detention basin, Green said. Because the study will take time to complete, these projects are years away from development and completion.
Harris County Commissioners Court authorized HCFCD to submit a grant application for the plan at its April 10 meeting. The study is estimated to cost $2.7 million, the majority of which will be covered by federal funding that will require a $680,000 local match.
Green said the Texas Department of Emergency Management and the Federal Emergency Management Agency are still reviewing the grant application. After the agencies approve the application, the study will take up to two years to complete.
Projects identified in the study will be funded by Harris County’s $2.5 billion bond program, which was approved by voters Aug. 25. The county has allocated $75 million in its bond program project list to carry out projects identified in the study; however, this number is subject to change depending on the study’s findings, said Jing Chen, HCFCD feasibility studies project manager.
Studying Lake Conroe
The two phases of the SJRA’s Flood Protection Project look at Lake Conroe and Spring Creek, which are both located upstream from Lake Houston.
The first phase of the study includes developing new hydrology and hydraulic models to better understand the flood plains and how flooding occurs near Lake Conroe, said Chuck Gilman, SJRA director of flood management. The updated models will also inform how the SJRA provides early warnings for flood risks and the timing for releases from the Lake Conroe dam.
Gilman said the two aspects of this study that will affect residents living downstream from Lake Conroe—including in the Lake Houston area—are the updates made to the SJRA’s flood warning system and the addition of rain gauges near Lake Conroe. He said these improvements will allow the SJRA to provide HCOEM with better information during a flooding event.
“We’re improving the models for rainfall and runoff,” said David Parkhill, director of raw water enterprise for the SJRA. “The technology today allows us to ... have data coming from these weather stations, going straight into the models and giving us a result to pass on to emergency management officials.”
The first phase of the study is funded by the Texas Water Development Board, the SJRA, Montgomery County and the city of Conroe, and is estimated to cost $920,000, according to SJRA officials. A final report on the study’s first phase is expected to be presented in February.
Spring Creek reservoir
Phase 2 of the SJRA’s plan will study the feasibility of a reservoir along Spring Creek and a real-time operations tool to determine how releases from Lake Conroe affect the region.
A reservoir near Spring Creek—which flows into the West Fork of the San Jacinto River—could hold back water during a storm and reduce peak water flows downstream, Gilman said.
This phase of the study is estimated to cost $1.1 million, according to SJRA officials. To fund the project, the SJRA submitted a grant application to the TWDB on July 11. If approved, the TWDB is expected to match 50 percent of local funds received. If funding is approved, the study would begin in early 2019 and take an estimated two years to complete.
“Unfortunately for those folks who are concerned about flooding again, these studies do take time, and it will be a slow process—even slower to build a flood control reservoir,” Parkhill said.
At its June 28 meeting, Humble City Council passed a resolution showing its support for the study. City Manager Jason Stuebe said because the city is located where Spring Creek flows into the San Jacinto River, the implementation of a reservoir along Spring Creek could prevent some city homes and businesses from flooding.
Last year during Harvey, homes within the city’s Northshire neighborhood—located south of Spring Creek—
sustained significant flooding.
Along with the Spring Creek reservoir, Stuebe said the predictive tool the SJRA plans to develop would also be helpful for the Lake Houston area because it would inform city and county officials how releases from Lake Conroe could affect areas located downstream.
Gilman said 10 to 20 percent of the water that flowed into Lake Houston during Harvey came from Lake Conroe.
“More information is good information, and it helps us prepare if—God forbid—we have another incident like Harvey,” Stuebe said. “It helps us in terms of planning, preparation and, if necessary, getting people to higher ground and out of danger.”
Additional reporting by Wendy Cawthon