The Harris County Commissioners Court approved a State Award letter in the amount of $2,708,208.00 (Federal $2,031,156.00 | Local $677,052.00) from the Texas Division of Emergency Management to provide necessary funding from the Federal Emergency Management Agency to complete a comprehensive San Jacinto Watershed Master Drainage Plan. The local match cost will be shared between the San Jacinto River Authority (SJRA), City of Houston, and Montgomery County.
The Harris County Flood Control District will work alongside the SJRA, Montgomery County, and the City of Houston to develop a comprehensive set of models for the entire Upper San Jacinto River watershed (including its major tributaries, from the headwaters in Walker County to the Interstate 10 crossing at the San Jacinto River in Harris County. The models will use consistent, cohesive methodology and rainfall rates regardless of the county in which those channels are located. The study is expected to complete on or before January 2022, which will include community engagement meetings to gather public input and comments to further refine the study results.
The results of the San Jacinto Watershed Master Drainage Plan will be used to update the Harris County Flood Control District Hazard Mitigation Plan and to identify future flood mitigation projects that can be implemented in the near- and long-term to reduce flood risk to people and property. The results will be coordinated with the participating partners so that they may also update their Hazard Mitigation Plans and to provide guidance on regulations for future growth within the study area. Information to be developed includes inundation maps for the studied streams that show the extent and depth of riverine flooding for an array of simulated storm events. Additionally, information will be gathered about the number of structures, acres of land, parcels, and miles of roadway that are located within the modeled floodplains. Although results from the study may be further refined in the future for insurance purposes, the mapping associated with this project will not be to the level of detail needed for official Federal Emergency Management Agency’s Flood Insurance Rate Maps.
This project will establish existing watershed conditions and analyze current flooding risks and vulnerabilities necessitating mitigation projects that may include large regional detention facilities, channel conveyance improvements, vegetation and sediment management activities, property buy-outs, and recommendations for additional gages at appropriate locations throughout the San Jacinto River Watershed. The project will prioritize flood risk reduction strategies, quantify the mitigation implementation costs, and develop information to help improve public awareness of flood hazards along the major tributaries.
The streams to be studied are located in seven different counties (Harris, Montgomery, Liberty, San Jacinto, Walker, Grimes, and Waller), covering an expanse of roughly 3,000 square miles within the study area. The stream length totals approximately 535 miles and includes West Fork San Jacinto River, East Fork San Jacinto River, San Jacinto River, Lake Creek, Cypress Creek, Little Cypress Creek, Spring Creek, Willow Creek, Caney Creek, Peach Creek, Luce Bayou, Tarkington Bayou, and Jackson Bayou.