Lake Lowering - Reduce Flooding

During Hurricane Harvey, the San Jacinto River Authority (SJRA) released almost 80,000 cubic feet per second from the Lake Conroe Dam. This amounted to ONE-THIRD of all the water coming down the highly populated corridor between Humble and Kingwood. Massive damage resulted.

How Lake Lowering Policy Started

Almost 6,000 structures along the West Fork flooded. That number includes more than 1,100 between Lake Conroe and Porter. Forty-four percent of all the businesses in the Lake Houston Area Chamber experienced damage. The release inundated entire subdivisions. They included Forest Cove townhomes, Barrington, Kingwood Cove, Kingwood Greens, Kings Harbor, and Town Center. Large parts of other subdivisions flooded, too. Some more than two miles from the West Fork.

After touring the damage, Governor Gregg Abbott directed the SJRA to reduce flooding. The SJRA established a Flood Management Division. It also adopted a temporary policy of lowering Lake Conroe in the rainiest months of Spring and during the peak of hurricane season.

The extra capacity provides a buffer against flooding downstream.

What is the Policy? How Long Will It Last?

The policy is temporary while the City of Houston works to add more gates to Lake Houston. Lake Houston can release only 10,000 cubic feet per second while the gates on Lake Conroe can release 150,000, 15X more.

The policy has evolved over time. It started with seasonal lowering to fixed levels for fixed amounts of time. Now the policy is called Active Storm Management. It allows more flexibility. The current policy represents a compromise between upstream and downstream residents. It will last through the end of 2024 and may be adjusted after that.

Active Storm Management Protocols
for Lake Conroe and Lake Houston – 2024

Spring

Beginning April 1 through June 1, the City of Houston may request diversions to lower Lake Conroe from normal pool of 201’ msl to create up to six inches of storage capacity for forecasted storm event inflows (to 200.5’ msl). The decision of when, how, and whether to initiate diversions will be guided by climate conditions, weather patterns, and available water supply.
Resume normal recapturing after each storm event that triggered any diversion between April 1 and June 1.
In the event a major rainfall is forecasted to impact our region, active storm management protocols of the City of Houston could initiate a diversion to create up to an additional six inches of storage capacity for storm inflows (to 200.0’ msl). It is acknowledged that under extraordinary weather circumstances, additional diversions to create capacity below 200.0’ msl could occur.

Fall

Beginning August 1 through October 1, the City of Houston may request diversions to lower Lake Conroe if actual lake levels are at normal pool of 201 msl to create up to six inches of storage capacity for storm inflows (to 200.5’ msl). After Labor Day, storage capacity may be increased an additional six inches (to 200.0’ msl). Diversion volumes requested to reach intended levels will be dependent on the actual lake levels. The decision of when, how, and whether to initiate diversions will be guided by climate conditions, weather patterns, and available water supply.
Resume normal recapturing after each storm event that triggered any diversion between August 1 and October 1.
If a named storm is predicted to impact our region, active storm management protocols of the City of Houston could initiate a diversion to create up to an additional six inches of storage capacity for storm inflows (to 199.5’ msl). It is acknowledged that under extraordinary weather circumstances, additional diversions to create capacity below 199.5’ msl could occur.

Protocol – Lake Houston

Year Round
- City of Houston will initiate releases to lower Lake Houston prior to major rainfall events.
- Conservation Pool Elevation is 42.4’ msl.
- Lake Houston level reduced to 41.4’ msl if a 24-hour rainfall forecast of 3 inches or more is expected. within the Lake Houston watershed.
- Under extraordinary weather circumstances, Lake Houston level may be reduced below 41.4’.

Duration

The Protocols above will extend to the end of 2024 but will be reviewed by the stakeholders in October/November of 2024. During the review, the stakeholders will discuss strategies that extend beyond 2024.

Advocacy and Education

All stakeholders will work to support flood mitigation projects and efforts across the upper watershed, including improvement of land use regulations to reduce runoff from new development in counties that contribute flow to Lake Houston.
Because public education regarding completed and ongoing downstream mitigation efforts is critical to generating upstream support for continued active storm management at Lake Conroe, all stakeholders agree to educate their constituents regarding: active storm management protocols being implemented at Lake Houston, completed and ongoing sediment removal projects in the San Jacinto River basin and Lake Houston, and continued progress on the Lake Houston spillway modifications.
Because of its impact on effective active storm management, all stakeholders will support City of Houston and SJRA efforts to amend the Certificate of Adjudication for Lake Conroe to increase the maximum diversion rate.
All stakeholders agree to support efforts to limit further construction of habitable structures around Lake Conroe below elevation 207’ msl.

Important Notes

All water released from Lake Conroe as part of active storm management is being accounted for from the City of Houston’s 2/3 share and reported to TCEQ by the City of Houston. Therefore, all final decisions on diversions are ultimately the City’s and must be communicated to the SJRA in writing. This includes defining active storm management protocols.
All flood mitigation protocols could be limited due to drought conditions.

Background Information

The links below provide information about how the policy came into effect.

For more information, search this site using the key words “lake lowering” or “active storm management.” You can also scroll through related posts on the right.