Flood Mitigation Snapshot | Print Snapshot (PDF)
Water is a finite resource and inconsistent in its availability – drought brings about too little water and storms can bring too much water and flooding. Texas has witnessed devastating floods caused by stalling storms coming from the west, as well as tropical storms from the Gulf of Mexico. In Central and West Texas, flash floods are a common danger. In hilly terrain, flash floods can strike with little or no advance warning. Likewise, the low plains and barrier islands along the Texas Gulf Coast are not only susceptible to flooding from poor drainage and overflowing riverbanks but also from storm surges due to hurricanes.
Flood mitigation planning protects against periods of extremely intense rainfall, over short periods of time that quickly claim lives, destroy property and disrupt the economy. The National Weather Service defines a flood as “any high flow, overflow or inundation by water which causes or threatens damages.”
Some forms of flooding are good for the environment and Texas terrain. Controlled flooding, for example, contributes to groundwater recharge and preserves floodplains that reduce the severity of larger flooding events and curb sedimentation and erosion. Maintained floodplains serve as a habitat for many plants and animals. The key to achieving these benefits are flood management and flood mitigation.
Structural flood mitigation includes seawalls, floodgates, levees, channel alterations, stormwater detention basins and other forms of landscape modification. Nonstructural mitigation includes open space preservation, residential relocation, wetland restoration, flood warning systems, participation in the National Flood Insurance Program, updates to zoning laws and building codes and other methods to decrease loss in high-risk areas.
In Texas, many surface reservoirs were built with the primary purposes of flood control and water supply storage. Dams assist in averting flooding and protecting lives and property by slowing the speed of floodwaters to a safer rate. About one-third of the state’s dams serve the purpose of flood mitigation, while one in seven are used for irrigation or water supply purposes.
An example of a system of dams used for flood mitigation and water storage is the Lower Colorado River Authority (LCRA). Established in 1934, the LCRA operates six dams – Buchanan, Inks, Wirtz, Starcke, Mansfield and Tom Miller – on the lower Colorado River in Central Texas, stretching from Austin to Llano. Lake Buchanan and Lake Travis serve as their region’s water supply, and all the dams assist with flood mitigation and the generation of hydroelectric power.
More than 2,000 dams have been built during the last 70 years in Texas. The Texas Commission on Environmental Quality’s (TCEQ) Dam Safety Program monitors and regulates private and public dams in the state.
Currently about 500 dams need rehabilitation and upgrades to meet safety criteria at an estimated cost of more than $1.5 billion, including anticipated federal and local match over a ten-year period. In 2019, $150 million was appropriated by the state legislature to repair and rehabilitate flood control structures across Texas.
At the direction of the legislature, the Texas State Soil and Water Conservation Board (TSSWCB) prepared and adopted a plan describing the repair and maintenance needs of flood control dams on May 21, 2020. The plan was provided to the Texas Water Development Board on June 11, 2020.
The Texas Water Development Board (TWDB) is charged with establishing a statewide flood mitigation planning process — separate from state water planning — and developing Texas’ first-ever state flood plan by September 2024, with five-year updates thereafter. The TWDB also administers a regional flood planning process comprised of 15 flood planning regions based on river basins (Exhibit 1). The first regional flood plans are due in January 2023.
Following the devastation of Hurricane Harvey in 2017, Texas voters approved a constitutional amendment, establishing the $800 million Flood Infrastructure Fund (FIF) program. The FIF program provides loans and grants for flood control, flood mitigation, and drainage projects. The FIF program offers no-interest loans and grants and in four project categories. As of July 2022, the TWDB reports 127 active projects, with more than $433 million in funding for these projects (Exhibit 2).
|Project Description||Category||Number of Active Projects||Amount Committed to Projects|
|Flood Protection Planning for Watersheds||1||46||$72,227,735|
|Planning, Acquisition, Design, Construction, Rehabilitation||2||67||$353,377,006|
|Federal Award Matching Funds||3||7||$5,967,628|
|Measures immediately effective in protecting life and property||4||7||$1,710,954|
|Total Committed Projects||127||$433,283,323|
Source: Texas Water Development Board
As became evident during Hurricane Harvey, Houston and its surrounding counties are particularly vulnerable to flooding. The Harris County Flood Control District is a special purpose district created by the Texas Legislature in 1937 and governed by the Harris County Commissioners Court in response to the devastating flooding that struck the region in 1929 and 1935 with mission to “provide flood damage reduction projects that work, with appropriate regard for community and natural values.” The district's jurisdictional boundaries include Harris County and the 23 primary watersheds within the county's 1,777 square miles. Each watershed has its own independent flooding problems.
In 2018, voters in Harris County approved a $2.5 billion bond measure to fund flood control measures throughout the county. The bonds will help fund more than 200 projects to reduce flood risk throughout Harris County including bayou expansions, reservoirs, canals and detention basins.
The Little Cypress Creek watershed encompasses 52 square miles in northwest Harris County and is one of the few largely underdeveloped watersheds in the county. The area is experiencing rapid development and currently lacks sufficient natural drainage to accommodate expected growth. The Little Cypress Creek Frontier Program was created in response to recent major flooding events and is part of a strategic effort to plan for and implement effective flood risk reduction projects, both for existing flooding issues and in anticipation of future development within the watershed. Funding from the $2.5 billion bond measure will cover 11 projects within the watershed totaling $143 million.
TWDB will provide the city of Ennis about $3.5 million in financing towards a flood management project along Cottonwood Creek to address drainage issues and prevent property damage. The improvements include the removal of 7,500 linear feet of debris, construction of a four-acre detention basin, stabilization of the creek channel bank and repair of five vehicular crossings.
The city of Wharton, in partnership with the U.S. Army Corps of Engineers, is in the process of building a system of levees, sumps, drainage features and control structures to address the city’s flood risk. The Wharton Flood Reduction Project – Levee Lower Colorado River-Wharton began construction during the summer of 2022.
In 2018, Hurricane Ike devastated Galveston Island and the surrounding area. A proposal was put forward to protect the area surrounding the Houston ship channel and the Texas Gulf Coast nicknamed the “Ike Dike.” In June 2022 the U.S. Congress passed the Water Resources Development Act of 2022 to authorize this $31 billion project, with funding expected through federal and local sources over the life of the project. The project would include a massive concrete gate system spanning a nearly 2-mile gap from Galveston Island to Bolivar Peninsula and be the largest civil engineering infrastructure project in the nation. The project could break ground as early as 2023 and will take approximately 19 years to complete.
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For additional insights, see The 2022 State Water Plan and Innovations in Texas Water Systems, Fiscal Notes, June-July 2022.