S O U T H F L O R I D A W A T E R M A N A G E M E N T D I S T R I C T

Southern Florida’s geography and climate dictate that we mayoccasionally experience flooding. South Florida Water Management

District; federal, state, and local governments; developers; andhomeowners’ associations share the responsibility for managingexcess water. Residents can help by learning about our regional

drainage system and reporting or correcting problemsboth before and after a storm.

Southern Florida’s terrain is flat—low andflat. From Lake Okeechobee south to FloridaBay, the slope of the land is only one inchper mile. Our climate is hot and wet withseasonal rains of 50 to 60 inches falling peryear, mostly in the summer. Marshes andswamps once covered much of the southernportion of the peninsula. Then, with the creationof a regional flood control system, the areawas opened for agriculture and development.More than 7.5 million people now call southernFlorida home and depend on the South Florida Water Management District to oversee theoperation and maintenance of our regional flood control system.

ON THE INSIDE

! Our Three-TieredDrainage System

! System Components

! Why PermittingIs Required

! Drainage Problems toLook For

! Understanding the Basicsof Flood Control

Managing Flood WaterBefore and After the Storm

A Three-Tiered SystemFlooding may happen in our area whenlarge amounts of rain occur over a shortperiod of time or from a single, heavystorm, tropical system, or hurricane. Afterthese storms, we rely on a man-madeflood control system to drain excess waterfrom the low, flat lands.

Flood control is achieved through aninterconnected drainage system. Ourthree-tiered system can be compared toa roadway system. Small streets inneighborhoods and towns carry traffic tolarger, secondary highways. Secondaryhighways, in turn, connect and carry trafficto turnpikes and superhighways, or ourprimary vehicle transport system.

Similarly, neighborhood ditches, swales,and conduits, referred to as our tertiarysystem, carry excess stormwater tosecondary canals. In turn, secondary canalsoperated by water control districts, cities,or counties connect and carry excess waterto our primary canal system. Primarycanals operated by the South FloridaWater Management District are thedrainage superhighways for our region.

Drainage Componentsand ConnectionsLarge and small structures,culverts, gates, weirs, pumps,and levees, even street gratesare all components of ourdrainage system. Water bodiessuch as ponds, lakes, andlagoons also play a role inwater management. While theydo provide a beautiful view,their real function is to holdexcess rainwater or to carry itoff to regional storage areas orto the ocean.

Swales and grassed waterstorage areas are importantfeatures in water managementsystems. In addition to storingand conveying water, they helprecharge water in theunderground aquifer and

improve water quality by catchingsediment and filtering nutrients.

Our interconnected system achievesmaximum benefit when all componentsare well maintained and kept in goodworking order. As in a chain of dominoes,each component must properly functionand connect to the next to allow foroptimum drainage conditions. However,even with well-engineered systems,flooding may still occur during and afterextreme rain events.

Factors Affecting DrainageExisting levels in surface waters andgroundwater affect the ability of drainagesystems to receive or store new rainfall. Ifsurface waters such as canals, lakes andrivers are already full, they cannot receiveor transport additional water. Just like ourhighways, when they cannot receive morecars from feeder roads because they arejammed or have reached their carryingcapacity, water cannot flow into primarycanals if they are full or if the flow hasbecome blocked. Additionally, if theunderground water table is already high,water cannot soak into the saturatedground. After a heavy rain, water instreets, swales, yards, and low-lying areasis expected and normal.

During and after storms, excess rainwateris typically discharged through canals andstructures to the ocean. However, tides,winds, and even the phase of the mooncan affect discharge to the sea. When tidesare high, the same floodgates that allowfor the flow of excess freshwater to theocean become salinity barriers preventingsaltwater from entering, or intruding intoour underground, freshwater aquifers.

Protection through PermittingDevelopment activities that affect howmuch rain soaks into the ground, howmuch water leaves a property, and whereit will go must be permitted by watermanagement districts. Permits protect thewater resources of the state and providefor adequate drainage while ensuring thatother people or properties are notadversely affected.

Permits also address water quality issuesand protect wetlands. Water leaving a

The South Florida WaterManagement District

operates the major canals,or drainage superhighways,for our region. These primarycanals are the first tier in ourthree-tiered drainage system.

property can transport excess nutrientsfrom fertilizers or animal wastes,herbicides, pesticides, oil, gasoline orother substances that can pollute waterand cause problems downstream.Wetlands are vital natural resourcesprotected by the state. They provide forwildlife habitat, flood protection,groundwater recharge, and waterquality benefits.

Drainage factors considered when issuingpermits are based on historical rainfalldata and generally address the followingthree levels of storm conditions:

• A Road Storm – 4 to 6 inches of rainfallin a 24-hour period. Water remainsstanding in yards, swales and ditches, butthe crowns of roads remain passable.

• A Design Storm – 7 to 10 inches ofrainfall in a 72-hour period. Roads, aswell as swales, ditches and yards flood,but buildings usually remain dry.

• A Hundred-Year Storm – 10 to 20 inchesor more of rainfall in a 72-hour period.Many houses and businesses can beexpected to flood.

In every county, some areas remainprone to flooding. Most are in olderneighborhoods where drainage systemswere in place before surface waterpermitting requirements wereestablished.

Helping to Maintain the SystemTo function properly, stormwater drainagesystems must be kept in good workingorder. Homeowners’ Associations, propertymanagers, and residents all play a role inmanaging flood situations by becomingfamiliar with the drainage system in theirown area and taking action when needed.

Just as northerners check their heatingsystems prior to winter, those who residein southern Florida should inspect,maintain and repair drainage systemsbefore the rainy season. Inspectionsshould be repeated when a major stormthreatens. This is what you should do:

• Find out if your neighborhood system isinspected regularly and check to see iftrash, dead vegetation and sediments arebeing removed.

• Become familiar with the permits thatauthorize drainage in your area and notechanges that may go beyond the specificsor intent of the permit.

• Keep a record of the names, addressesand phone numbers of your Homeowners’Association or property manager, the localdrainage district, and the South FloridaWater Management District to reportpotential problems.

Recognizing Drainage ProblemsResidents, property managers, orcontractors should periodically check

Drainage system componentssuch as pipes, culverts,

swales, and grassy areasneed regular maintenance.Taking action to report orcorrect potential problems,especially before the rainy

season, is an effective way inwhich you can help keep our

interconnected system inworking order.A road storm produces 4 to 6 inches of rainfall in a 24-hour period. Due to our unique climate

and geography, standing water is normal and can be expected after a heavy rainfall.

The South Florida Water Management District is a regional, governmentalagency that oversees the water resources in the southern half of the state. It is theoldest and largest of the state’s five water management districts.

Our Mission is to manage and protect water resources of the region by balancingand improving water quality, flood control, natural systems, and water supply.

EN09/09/09

South Florida Water Management District3301 Gun Club RoadWest Palm Beach, Florida 33406561-686-8800 • 800-432-2045www.sfwmd.gov

MAILING ADDRESS: P.O. Box 24680West Palm Beach, FL 33416-4680

DID YOU KNOW?

! Maintenance and upkeep ofcommunity drainage facilities aretypically the responsibility ofHomeowners’ Associations.

! Standing water in streets andyards is not considered unusual,but rather a critical componentof your neighborhooddrainage facilities.

! Weather conditions and waterlevels are monitored around theclock, 365 days a year, andfloodgates are opened if heavyrains are expected.

! If you live in an area serviced bya local drainage or water controldistrict, it is noted on your countyproperty tax bill.

! A portion of the property taxesyou pay to the South FloridaWater Management District isfor regional flood protection.

! “Freddy,” the friendly alligator,appears on canal signs locatednear all primary canals operatedby the South Florida WaterManagement District.

the components of the drainage system toensure peak performance. Inspectionsshould include:

• Stormwater inlets, pipes andculverts: Grates should be unobstructedand sediment under the grate should beremoved. Pipe openings and connectionsto culverts should be free of sediment,trash, and debris.

• Swales and grassed water storageareas: Swales may need to be regradedor replanted. It is a good idea to comparethe existing slope to the permitted designplan before the work begins. All heights,depths, and lengths of side slopes mustmeet permit specifications. Grassed swalesalso require regular mowing, andundesirable exotic vegetation shouldbe removed.

• Ditches or canals: Trash, sediment,and dead vegetation should be completelyremoved and properly disposed of so itwon’t affect any other water conveyancesystem or water storage area. Right-of-way clearances should remain openand unobstructed.

• Lake systems: Trash and deadvegetation should be cleared from theshoreline. Shoreline grasses should bemowed, unless it is a wetland preserve.Side slope erosion or washouts on thebanks should be repaired and replanted.Pipe or culvert connections between lakesshould be clear and open.

• Weirs or other discharge controlstructures: Check for obstructions.Anything that hinders water flow shouldbe removed. The structure should have a“baffle” or trash collector to prevent flowblockage and hold back floating oils anddebris from moving downstream.

• Dikes and berms: Worn-down bermsand rainfall-created washouts should beimmediately repaired, compacted andreplanted in compliance with the permit.

Our Wet Way of LifeUnderstanding our way of life is knowingwe live in a region where seasonal rainsfall over low, flat lands that offer littlenatural drainage. Most drainage isthrough interconnected waterways andstructures. Our three-tiered systemrequires ongoing maintenance and repairfor optimal performance. Action should betaken before the rainy season.

You can help to lessen the odds that yourhome or community will flood by learningabout our regional flood control systemand reporting or correcting problems.Flood management is a sharedresponsibility and you can makea difference.