May 2025
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. Water control structures vary greatly in size and are used for multiple purposes. The District’s water control structures can be classified into three main categories: flood control, salinity barriers, and water conservation structures. These structures allow the District to provide flood control, water conservation, and water supply protection, as well as preserve water quality and environmental assets.
Q: What is a flood control structure?
A: The District has 17 structures that are designated for flood control. Flood control structures are permanent structures that are specifically designed and used for reducing flood impact on the area. Flood control structures and their corresponding canals are designed to handle very large capacities of water for a sustained period. The District has guidelines which provide guidance on when to operate the flood control structures.
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, constructed in response to massive flooding caused by Hurricane Donna in 1960, and is made up of three elements: the Hillsborough Flood Detention Reservoir, the Tampa Bypass Canal and the Harney Canal. Flood waters from the Hillsborough River can be impounded into the 16,000-acre Hillsborough Flood Detention Reservoir. As the reservoir fills with water from the river and the surrounding 450-square-mile watershed, the flows then enter the Tampa Bypass Canal, which has five flood control structures that control the flow as the water moves safely to McKay Bay, protecting the cities of Temple Terrace and Tampa from flooding along the Hillsborough River. 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. These structures are mainly operated during summer rainstorms to assist in maintaining water levels. Their primary purpose is to protect and maintain natural systems. 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.
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. Structure S-551 is a salinity barrier located on Lake Tarpon in Pinellas County. The structure keeps saltwater from intruding into Lake Tarpon from Tampa Bay. The S-551 structure is a dual-purpose structure as it is also designated a flood control structure.
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, including the 17 flood control structures, are operated remotely by a computer. This allows staff to operate structures 24/7 from any location where there is internet access. Manually operating a structure is defined as having to be physically at the structure location to make an operation. Approximately half of the District’s water control structures must be 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 Status Map. Gate status and water levels are updated hourly for each water control structure location, however data may be temporarily unavailable during power outages. To access the map, visit WaterMatters.org/projects/structure-operational-guidelines.
Andrew Linch
Structure Operations Manager