May 2026
Q: What is a water control structure?
A: The primary purpose of the District’s water control structures is to manage the flow of water in lakes and river systems. Water control structures vary greatly in size and complexity. The District’s water control structures can be broadly classified into three categories: flood control, water conservation, and salinity barriers. Collectively, these structures allow the District to reduce flood risks, conserve water, protect water supplies, preserve water quality, and maintain environmental flows.
Q: What is a flood control structure?
A: The District has 17 structures designed primarily for flood control. Flood control structures are engineered systems with operable gates that reduce flood impacts in a watershed. Flood control structures and their corresponding canals are designed to manage very large volumes of water for a sustained period.
Q: What is the largest flood control structure system in the District?
A: The largest flood control structure system in the District is the Tampa Bypass Canal System, which protects the cities of Temple Terrace and Tampa from flooding along the Hillsborough River. The system was designed and constructed by the U.S. Army Corps of Engineers in response to massive flooding caused by Hurricane Donna in 1960. It is made up of three elements: the Hillsborough Flood Detention Reservoir, the Tampa Bypass Canal and the Harney Canal. When water levels in the upper Hillsborough River near flood stage, the District can impound the Hillsborough River into the 16,000-acre Hillsborough Flood Detention Reservoir. As the reservoir fills, water is routed into the 15.7-mileTampa Bypass Canal, which has five flood control structures to safely move the water into McKay Bay. In the days following Hurricane Milton in 2024, the Tampa Bypass Canal was diverting 7.2 billion gallons of water per day during the peak of that flood event.
Q: What is a water conservation structure?
A: Most of the District’s structures are water conservation structures, used to conserve or hold water in lakes during dry times. Water conservation structures are not designed for flood control and do not have the ability to move large volumes of water caused by large rainfall events. These structures are mainly operated during summer rainstorms to assist in maintaining water at optimal levels. Their primary purpose is to protect natural systems and manage water levels for recreational purposes.
Q: What is a salinity barrier?
A: The primary purpose of a salinity barrier is to prevent salt water from penetrating inland into freshwater channels and lakes. For example, Structure S-551 is a salinity barrier located on the Lake Tarpon Outfall Canal in Pinellas County. The structure keeps saltwater from Tampa Bay from intruding into Lake Tarpon. The S-551 structure is a dual-purpose structure as it is also designated for flood control.
Q: How are the structures operated?
A: Water control structures can be operated remotely or manually. All the District’s mission-critical water control structures are operated remotely by a computer. This allows staff to monitor and operate structures 24 hours a day/365 days per year from any location where there is internet access. Manually operating a structure requires the operator to be physically present at the structure location to make an operation. Approximately half of the District’s water control structures are manually operated.
Q: How can I find out if the District is operating a structure during a storm event?
A: Structure gate status and water levels are available on the District’s interactive Water Control Structure Dashboard. Gate status and water levels are updated hourly for each water control structure, however data may be temporarily unavailable during power outages. To access the map, visit WaterMatters.org/projects/structure-operational-guidelines.
Jonathan Annis
Structure Operations Manager