Reminder: SJRA Joint-Reservoir-Operations Meeting in Humble

3/4/26 – The San Jacinto River Authority (SJRA) will hold a meeting at the Humble Civic Center to solicit public input on its Joint-Reservoir-Operations Study. Please come:

• March 5 @ 6:00 pm – 8:00 pm
• 8233 Will Clayton Pkwy, Humble, TX 77338

Representatives from the SJRA, Coastal Water Authority, City of Houston, Humble, and the study consultant, Black & Veatch Engineering, will explain the study and field your questions. The meeting will feature informational tables where residents can talk with engineers one on one, plus a presentation.

According to Matt Barrett, PE, SJRA’s Water Resources and Flood Management Division Manager, “one of the main objectives of the study is to determine if there are any benefits to pre-releases from Lake Conroe and Lake Houston.”

Not an Easy Question

While that may seem obvious to flood victims, the question can get complicated. In involves an almost infinite number of weather scenarios, engineering variables and water-supply considerations. For instance:

• How much rain will fall and how fast? Which direction will the storm come from? Where will the most rain fall in the river basin?
• How many gates can the budget support? Will they be able to keep up with Lake Conroe’s discharges?
• What happens if a storm veers away at the last minute? How can we make sure pre-releases don’t waste water or flood downstream neighbors?

In my mind, the question is not “if” pre-releases have a benefit, but “when.”

And that relates to a second objective of the study: to develop a flow forecasting tool for the entire river basin.

Accordingly, said Barrett, “The study will also consider the travel time of water between Lake Conroe and Lake Houston, a factor that’s crucial in evaluation of pre-releases.”

Experience of Other River Basins

Coordinating pre-releases from multiple dams is not an unusual problem. Most rivers have more than one. For instance, multiple dams on the lower Colorado River help keep Austin from flooding.

There’s a well-established body of work showing that coordinating operations across multiple reservoirs can produce measurable flood-mitigation benefits. However, hydrology, travel times, and downstream constraints must align. 

The big win is usually shaving peak flows. Engineers in other watersheds have seen flood-mitigation benefits when their studies identified operating rules that:

• Prevented “release stacking” – We must avoid upstream releases arriving at the same time as peak local inflows from other uncontrolled tributaries, such as the East Fork or Spring and Cypress Creeks
• Used forecasts intelligently – Pre-release only works when forecast confidence and downstream capacity justify it
• Respected downstream constraints – Don’t exceed channel limits. 

Make-or-break technical questions for the San Jacinto Watershed will likely include:

• Travel time for water between Lake Conroe and Lake Houston and how that changes with different base flows.
• Downstream constraints such as local rainfall in the Lake Houston watershed
• Forecast confidence and decision triggers – When will forecasts be reliable enough to justify pre-release without wasting water supply or making flooding worse.
• What will the study optimize for? Peak flood stage at specific gages? Total damages? Avoiding emergency spillway use? Protecting evacuation routes? Something else?

Bring your questions to the Civic Center.

Why is This Study Taking So Long?

The project was delayed by a change in plans in adding gates to the Lake Houston Dam. SJRA first applied for a grant to study synchronizing releases from the two dams back in 2020. However, after crest gates to the spillway portion of the dam proved infeasible, the City of Houston decided to study adding tainter gates to the earthen eastern portion of the dam.

That new study is now 30% complete. That’s far enough along to start making engineering decisions. But to complicate things even further, costs have escalated because of inflation. That raises some additional questions…and scenarios. How many gates can the City afford? Will they be able to keep up with releases from Lake Conroe? And will Black & Veatch even examine scenarios involving additional gates?

If history is any indication, you can bet that members from the Lake Conroe Association will be there to talk against pre-release. If you want your interests represented in this study, make sure you come tomorrow night. And make sure they include the scenarios in their study that represent your biggest concerns.

Posted by Bob Rehak on 3/4/26

3109 Days since Hurricane Harvey