Compromise on Flood Mitigation Protocols for Lake Conroe and Lake Houston – 2023

Protocol – Lake Conroe

Spring

• Beginning April 1, the City of Houston may initiate diversions to lower Lake Conroe to create up to six inches of storage capacity for storm 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 June 1.
• In the event a major rainfall is forecasted to impact our region, the City of Houston may use active storm management protocols and 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, the City of Houston may find it necessary to create capacity below 200.0’ msl.

Fall

• Beginning August 1, the City of Houston may initiate diversions to lower Lake Conroe 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).  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 October 1.
• If a named storm is predicted to impact our region, the City of Houston may use active storm management protocols and 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, the City of Houston may find it necessary to create capacity below 199.5’ msl.

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 24-hour rainfall forecast of 3 inches or more.

Duration

• The Recommended Protocols above will extend to the end of 2023 but will be reviewed annually by the stakeholders in October/November of 2022 and 2023.  During the annual review, the stakeholders will discuss strategies that extend beyond 2023.

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 seasonal lowering of 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 daily 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 seasonal lake lowering 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.