Operable Control Structure

Operable & Non-Operable Structures

In coordination with the South Florida Water Management District permit, the Lake Worth Drainage District (LWDD) allows two types of discharge control structures in residential communities and commercial properties – Operable and Non-Operable. The labels Operable and Non-Operable do not pertain to the structure’s ability to provide flood protection, but rather identify the type of structure and the way it is designed to function.

Bleed Down Orifice graphic

Figure 1. Discharge Control Structure

Non-Operable Structures, also known as ‘passive structures’, typically have an overflow weir or a triangular “bleed down” orifice installed at the stormwater pond’s designed water-control elevation. These overflow orifices allow the gravity flow of water through the structure and into drainage canals until the pond water rests at the designed water-control elevation. Given its passive nature, water will flow through the structure virtually any time there is rainfall except during very dry conditions when pond levels are lower than the water-control elevation.

So, why are there Operable Structures? A series of normal rain events can sometimes raise the level of the stormwater pond faster than the Non-Operable Structure can remove the water. The Operable Structure includes the passive flow described above, as well as a vertical slide-gate with an operating mechanism (usually a hand-wheel) that can be manually opened or closed to control the rate of water flow from the pond to drainage canals. The Operable Structure can be opened to manually lower the pond elevation after a rain event or before major weather systems like tropical storms or hurricanes.

It is important to note that the Operable Structure can only be opened with permission from LWDD. Sometimes that permission is granted at the request of an individual community or business. However, more often LWDD will give blanket permission to all communities and businesses based on forecasted weather conditions. In those situations, LWDD will provide notification by email and give a specific time to operate the Operable Structure. Communities and businesses can register designated representatives to receive these notification emails at

LWDD is the only drainage district in the State of Florida that allows Operable Structures.  It requires close coordination with local and regional authorities, but we believe it provides flood control benefits to the residents living within the LWDD boundaries.

Graphic of plumber

Septic Systems and Flooding

During heavy rainfall, the soil around the septic tank and in the drain field can become saturated. The effluent may not be able to properly drain through the soil. By taking special care with your septic system after flooding, you can contribute to the health of your household, community and environment. For more information, download the University of Florida’s tips sheet – CLICK HERE.

Graphic of women in flood

Your Health & Flood Water

Summertime rainstorms can bring heavy rainfall with localized ponding in swales, roadways and front yards. These low-lying areas are designed to hold stormwater to keep our homes dry. But weather is unpredictable and severe rainfall in a short period of time may overwhelm the drainage system causing flooding.

Should you encounter flood water, remember that basic hygiene is critical.  Wash your hands with soap and water that has been boiled or disinfected before preparing or eating food, after toilet use, after participating in flood cleanup activities and after handling articles contaminated with flood water.

Avoid eating or drinking anything that has been in contact with flood water. Flood water may be contaminated with fecal matter or other pollutants, so do not wade through, or allow children or pets to play in standing water. If you have any open cuts or sores and cannot avoid contact with flood water, keep them as clean as possible by washing with soap to control infection.  If a wound develops redness, swelling or drainage, seek immediate medical attention.

Remove and discard absorbent household materials, such as curtains, rugs, and Sheetrock.  Clean all walls and hard-surfaced floors with soap and water and disinfect with a solution of 1/4 cup of bleach to one gallon of water.  Thoroughly disinfect surfaces where food may come into contact such as counter tops, refrigerators, and tables. Wash all linens and clothing in hot water.

Saturated ground soil can place stress on residential septic systems. If on a septic system and your plumbing is functioning slowly there may be a problem with too much ground water. To help reduce the stress on the septic system, conserve water as much as possible. The less water used the less water the septic tank must process. Do not have the septic tank pumped as exceptionally high-water tables might crush a septic tank that was pumped dry.

During severe weather events, the Lake Worth Drainage District (LWDD) monitors the canal water elevations and makes operational adjustments to the system. However, we still want to hear from residents and businesses within our boundary who may be experiencing flooding issues. Report flooding by calling the main office number 561-498-5363 or sending an email to

Resident Alice Finst on bank of LWDD canal looking at danger sign.

Water Safety Around Drainage Canals

South Florida is an aquatic playground during hot summer months. The Lake Worth Drainage District’s canal system can appear to be an ideal place to cool-off and swim or spend a day fishing. However, it is important to understand that these inviting waterways can be dangerous.

District canals were not created for recreational use. They are designed to collect and convey stormwater to provide both flood control and water supply for residents and businesses within our boundary. Operation of this flood control system includes large water control structures which when opened can create a sudden change in a canal’s water elevation, as well as strong currents that may not be visible on the water’s surface. This current can catch swimmers and boaters by surprise. If close to an open structure, the undertow can create a strong enough force to pull swimmers and small boats under.

Canal rights-of-way do not have protective barriers, and banks may give way due to the soft sandy soil and rocks below. Once a person is in the water, it can be very difficult to climb out due to the steep side-slope of the canal bank. Depending on the time of day or location of the canal, cries for help may not be heard.

Many invisible dangers and submerged hazards exist in the canals like broken glass, scrap metal, bottles and cans, as well as wild animals. It is not unusual to see alligators, snapping turtles and snakes living in and near canals. Diving into a drainage canal is particularly dangerous because canal depths can vary significantly, and subsurface aquatic vegetation can tangle around extremities.

Stay safe and follow a few simple rules. Do not swim in a canal, instead head to the pool or beach. Keep a safe distance from the canal bank to avoid falling in the waterway. Always stay clear of water control structures. Visit the Drowning Prevention Coalition’s website for more water safety tips at

Rain flows down from a roof down

7 Fast Facts On Flood Control

Increase your knowledge about community flood control by downloading LWDD’s flyer, 7 Fast Facts On Flood Control, and get started on becoming informed partners in providing flood control.

7 Fast Facts