Month: March 2026

Summary & Feedback from Bob Rehak’s Reduce Flooding Blog (https://reduceflooding.com/blog/)

SJRA Joint-Reservoir Operations Study Meeting: A Wake-up Call

3/7/26 – On 3/5/26 at the Humble Civic Center, the San Jacinto River Authority (SJRA) held the first of three meetings to discuss its Joint Reservoir Operations Study. In several respects, the meeting was a wake-up call:

• During Q&A, SJRA learned how impatient the downstream public is for flood-mitigation solutions – 8.5 years after Hurricane Harvey.
• Public comments showed that PTSD from flooding still lingers.
• The average age of attendees appeared to be in their sixties. Younger homeowners and newcomers to the region who have no memory of flooding were largely absent.
• Several comments by speakers suggested upstream residents around Lake Conroe are still resistant to the idea of any “pre-release.”
• SJRA has no formal pre-release program anymore. As one speaker said, “There are no designated dates or amounts or anything like that. But we work very closely with City of Houston. They make decisions on what we’d like to do.”

Theory of Pre-Release

The idea behind “pre-release” is to release water ahead of a storm, so a reservoir, such as Lake Conroe or Lake Houston, has additional capacity to absorb incoming floodwater. That can shave flood peaks by spreading out releases over longer periods.

SJRA’s Water Resources and Flood Management Division Manager Matt Barrett, PE, said…

“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.”Matt Barrett

Findings in Other River Basins

Studies around the world have proven that pre-releases do have benefits … in certain conditions.

California Department of Water Resources found that “weather-informed reservoir operations” at Lake Oroville and New Bullards Bar Reservoir can further reduce flood risk for communities along the Yuba and Feather rivers during extreme atmospheric river storm events and potentially benefit water supply during drier periods.

Also in California, the Army Corps of Engineers found that “forecast-informed reservoir operations” could increase water supply without increasing flood risk.

In the Delaware River Basin, a “flexible flow management program” mitigates flooding impacts immediately downstream of reservoirs.

A peer-reviewed Journal of Hydrology case study on the Bavarian Danube concluded that coordinated operation of reservoirs in river basins has great potential to improve flood mitigation.

City of Houston Experience

And experience in the San Jacinto River Basin since Harvey has also proven pre-releases have benefits. The City of Houston Public Works Department has documented numerous instances when pre-releases helped prevent downstream flooding, according to Dave Martin, former Houston Mayor Pro Tem.

Pushback from Lake Conroe Association

But pre-release is politically unpopular with Lake Conroe residents. The Lake Conroe Association (LCA) constantly speaks out against it in SJRA board meetings, lawsuits, community meetings, and with the TCEQ. While LCA articulates its concerns as a loss of valuable water, the concerns stem from perceived impacts on recreation and property values.

Iterations of Lake Conroe Pre-Release Strategies

As a result, SJRA has modified its pre-release protocol several times since Harvey.

• At first, SJRA lowered Lake Conroe during the two wettest seasons of the year: Spring and Hurricane Season.
• SJRA then restricted the amounts and durations of the lowering.
• Currently, SJRA lowers Lake Conroe on an as-needed basis – days or hours before major storms. They call the strategy “Active Storm Management.”

The City of Houston owns two-thirds of the water in Lake Conroe and can call for as much as it wants, any time it wants. SJRA reportedly would prefer the City continues calling for the water, so that it doesn’t have to take the heat from the Lake Conroe Association.

Clearly, Active Storm Management is a compromise between upstream and downstream interests. But how does SJRA know when and how much to release before a storm. That depends on weather and the certainty of forecasts. How much rain will fall where? How fast? And how much will run off?

Another Study Objective: Forecasting Tool

That’s where another objective of the Joint Reservoir Operations Study comes in: development of a forecasting tool.

See more details about the forecasting tool below.

The question in my mind is not IF pre-lease is feasible, but WHEN. Clearly, there are some cases where pre-release from Lake Conroe alone does not make sense, i.e., when a storm approaches from the south, as Harvey did and Lake Houston (without its new flood gates) could not release water fast enough to keep up with any release from Conroe. That would just make flooding worse.

But in other situations, i.e., when a storm approaches from the north or northwest, it might make sense – especially after Lake Houston receives its new floodgates. Then you would not be stacking floodwaters from different directions on top of each other.

Scope of Work Associated with Study

The Joint Reservoir Operations Study will also look at past releases from both Lake Houston and Lake Conroe, and use lessons learned to help inform the Lake Houston Gate Operations Policy.

With the data collected, SJRA will develop models that reflect the addition of new gates for the Lake Houston Dam. Then they will evaluate 20 different pre-release scenarios, such as the possibilities mentioned above.

As of this meeting, SJRA had not yet determined which scenarios they would evaluate. However, they will evaluate the consequences on water supply in both lakes.

The worry: if the forecast is wrong and a storm veers away, pre-releases could negatively impact water supply.

Finally, the study will determine the best ways to communicate pre-releases to stakeholders.

The Flow-Forecasting Tool mentioned above will incorporate data from multiple sources, including rainfall, a network of more than 70 stream gages, outflow from Lake Conroe and a model of the watershed. It will inform both gate operations and local officials.

To see the entire presentation, click here. It will help you understand some of the constraints on dam operations including:

• Governance of the reservoirs.
• Components of Lake Houston Water Supply Operations
• Historical floods
• Proposed improvements to the Lake Houston Dam
• Runoff from sub-watersheds
• Differences between water-supply and flood-control reservoirs; Lakes Conroe and Houston are both water-supply reservoirs
• Construction differences between the two dams

Next Meetings and More Information

As the study progresses throughout the year, SJRA will hold two more public meetings. A mid-year meeting will be held at Lake Conroe to review progress. And SJRA hopes to reveal the results of the study in The Woodlands before the end of the year.

For more information, see LCLHJointOps.com.

Even if you can’t make the meetings, SJRA welcomes public comments on the study, flood-risk locations and flood impacts.

Posted by Bob Rehak on 3/7/26

3112 Days since Harvey