Control Structure general

A Diversion And Impoundment System

The Lake Worth Drainage District (District) is considered a ‘Diversion & Impoundment’ water management system under the South Florida Water Management District (SFWMD) rule for consumptive water use. A diversion and impoundment system will divert surface water through a pump or water control structure, or a combination of surface and groundwater to a conveyance canal which the owner has legal control to operate and maintain for the purposes of providing for the reasonable and beneficial demands of secondary users.

There are two categories of secondary users, independent and dependent. The distinction between these two categories is related to the way the secondary user attains its consumptive water use right. Unless exempt, independent secondary users must obtain a consumptive water use right through their own South Florida Water Management District permit. Dependent secondary users may be incorporated into the Lake Worth Drainage District’s permit. An example of an independent user is a municipal water utility or residential community with retention ponds/lakes. Dependent users may be agricultural landowners or individual property owners who have historical water use rights.

The District’s main source of consumptive water use is allocated from SFMWD canals and Water Conservation Area 1. Because the water within the District’s canal system is used to recharge the surficial aquifer and some municipal wellfields, it is important to keep water levels in the canals at beneficial elevations to protect drinking water supplies.

Fiscal Year 2019 Budget Approved

On August 15, 2018 the LWDD’s Board of Supervisors adopted the fiscal year 2019 operating budget. The approximate $18 million budget reflects LWDD’s continued commitment to maintenance and operations with substantial resources appropriated for canal rehabilitation, and the refurbishment/replacement of major flood control structures. For more information, visit our website https://lwddnet.wpengine.com/about-us/financial-information.

 

maintaining canal

What Is Meant by a “Well-Maintained” Canal?

The Lake Worth Drainage District’s canals exist for the purposes of flood control and water supply. Through its network of over 500 miles of drainage canals, the District provides stormwater management making the area suitable for residents, businesses and agriculture. Effective flood control is dependent on well-maintained canals and rights-of-way. But what defines “well-maintained”? A canal or right-of-way that some property owners may consider an eyesore is often considered well-maintained for effective flood control operations of the District.

Some of the necessary components for effective flood control include the free flow of water in the canal channel to divert excess stormwater from properties, and unencumbered canal rights-of-way to provide access for regular maintenance and emergency response. Through the process of aquatic vegetation removal and canal bank mowing, effective flood control is achieved.

There are numerous species of aquatic plants found within the District’s canal system. Some aquatic vegetation has the potential to slow the flow of water within the canal channel or large flood control structures. The Lake Worth Drainage District staff controls aquatic vegetation growth with the application of herbicides and mechanical removal. Although not esthetically pleasing to some property owners, algae in canals is not a threat to flood control. Because algae are very small plants that break apart easily, they can pass through drainage pipes and control structures. This is good news since the herbicide used to treat algae can be harmful to the water body.

Canal rights-of-way and banks are mowed approximately four (4) times a year. Flat-mowers mow the rights-of-way, and arm-mowers maintain the side slopes of the canals. High grass does not prevent access to canals and control structures or threaten flood control operations. Grasses and other vegetation can grow several inches in height before mowing crews return to an area. Since these areas are not fertilized or irrigated, a quarterly mowing schedule allows for the seeding and regrowth of grasses.

Although most property lines do not extend to the water’s edge, some property owners adjacent to the right-of-way may choose to maintain the grass to a higher degree through irrigation and more frequent mowing. However, this higher degree of maintenance is at their cost and no encroachments such as trees or shrubs are allowed.

Flood control and the maintenance it requires comes at a cost. All property owners within the Lake Worth Drainage District boundary, whether adjacent to a canal or miles away, are assessed at the same tax rate base on the amount of land owned. In 2019, the non-ad valorem assessment rate is $49.50 for a parcel equal to or less than an acre in size and is established by the Board of Supervisors. By providing well-maintained canal rights-of-way necessary for flood control operations, the Lake Worth Drainage District can achieve its mission of effective flood control at an affordable cost for all residents.

L-50 Canal east Boca Raton After Hurricane Irma

LWDD’s Canal Rehabilitation In The City of Boca Raton

At the request of Mayor Scott Singer on behalf of the City of Boca Raton, the Lake Worth Drainage District Board of Supervisors agreed at its July 11th Board Meeting to postpone vegetation removal along the L-48, L-49 and L-50 Canal rights-of-way within the City of Boca Raton. This postponement will allow the District and City the opportunity to work together and consider options for necessary canal rehabilitation on these canals prior to final action by the District’s Board of Supervisors on October 17, 2018.  The District will be moving forward with the following necessary canal work.

L-48 Canal:

  • Removal of stacked vegetation that was previously cut from right-of-way
  • Stump grinding vegetation previously cut along the south bank
  • Dredging silt from a portion of the channel adjacent to I-95
  • Excavation of shoaling east of Southwest 9th Avenue as may be necessary

L-49 Canal:

  • Placement of erosion control mats (jute fiber) along the top of canal banks west of 12th Avenue
  • Stump grinding of rubber tree previously removed west of Southwest 9th Avenue

L-50 Canal:

  • Inspection of outfall pipe located west of Southwest 8th Avenue, and remedial work of such as may be necessary
  • Removal of shoaling between 9th and 12th Avenues

Residents are reminded to take proactive measures for hurricane preparedness and sustainable tree maintenance by pruning trees away from drainage canals and refraining from planting trees or vegetation on drainage or utility easements and public rights-of-way.

Additional information and video on the District’s Canal Rehabilitation Program can be found on our website at https://lwddnet.wpengine.com/canal-maintenance/canal-rehabilitation. The City of Boca Raton’s website provides civic alerts at https://www.myboca.us/.

Weeds in canal captured by boom

Managing Vegetation Growth In Canals

With more than 500 miles of canals under its jurisdiction, the Lake Worth Drainage District is continually conducting maintenance operations of its waterways. Effective flood control is dependent on well-maintained canals. Personnel are in the field daily to ensure the system is operating efficiently and the water is free flowing.

Licensed applicator

One of these maintenance activities is the control of aquatic vegetative growth in the channel. To accomplish this task, LWDD utilizes two methods, herbicide application and mechanical. Given the proliferation of aquatic vegetation in South Florida’s tropical climate, it is necessary to use herbicide treatment to control growth. When applying herbicides, LWDD strictly adheres to the rules and regulations established by the U.S. Environmental Protection Agency and the Florida Department of Environmental Protection. Staff members applying chemical treatments are trained and certified annually on the proper application and handling of all herbicides used.

Mechanical removal includes the use of containment booms which are floating ribbon-

Grapple tuck used for removal

Aerial view of containment booms

like structures that span the canal and extend approximately one foot both above and below the water’s surface. As water flows through a canal or winds blows across the water’s surface, floating debris will move through the canal network. The booms serve as a physical barrier, collecting the debris while allowing water to continue to flow unimpeded. District crews can then remove the captured debris mechanically with the use of a grapple truck. The use of these booms also reduces the use of herbicides by facilitating a more centralized and controlled location for application rather than treating entire reaches of canals.