SOUTH FLORIDA WATER MANA GEMENT DISTRICT

The Everglades are at risk from excess nutrients found in

stormwater runoff. These nutrients flow from lawns, farms,

roadways and other developed areas. Stormwater Treatment Areas

are constructed wetlands that remove excess nutrients. They play a

vital role in protecting and restoring America's Everglades.

Rainfall is South Florida’s primary source of fresh water. It nourishes plants, fills ponds and

seeps into the underground aquifer, replenishing the drinking water supply. In excess, it drains

away in the canal system that protects

South Florida from flooding. 

Stormwater runoff also carries nutrients

off the landscape, especially fertilizers

used in suburban, agricultural and

urban settings. Scientists have determined that a common ingredient in fertilizer – phosphorus – has put the

fragile Everglades environment at risk.

Phosphorus is a mineral that is essential for all life. It forms genetic material,

builds bones and teeth and aids metabolism. But when excess phosphorus

reaches natural wetlands like the Everglades, it does more harm than good. 

ON THE INSIDE

■ Investing in a solution

■ “Green” technology at 

work

■ Meeting mandated goals

■ Benefits to birds and

wildlife

■ Sustainability for the

future

Stormwater Treatment Areas

Managed wetlands improving Everglades water quality
Phosphorus and Its Impact

The Everglades is naturally a low-nutrient

ecosystem. South Florida’s native wetland

plants are adapted to this condition and

thrive there. When a nutrient, such as

phosphorus, enters this ecosystem in

excess, plant growth is stimulated, producing an overabundance of undesirable

vegetation. Cattail and other species

respond with vigor, crowding out native

wetland plants such as sawgrass and preventing the sun’s rays from reaching

plants in the water. When this happens,

aquatic insects, crustaceans and other

invertebrates do not have enough to eat or

enough oxygen to live, which means the

fish and birds do not have enough to eat

either. The impact of excess phosphorus in

the Everglades is far-reaching indeed.

Investing in a Solution

The good news is that the State of Florida

has invested more than $1 billion in

water-quality improvements aimed at lowering phosphorus levels. A decade ago,

before these improvements were put into

place, phosphorus concentrations in Everglades-bound waters averaged 170 parts

per billion (ppb). Today, as a result of

Florida’s efforts, the concentrations in discharges to the Everglades are as low as

12 ppb, repeatedly surpassing the predictions for what could be achieved.

“Green” Technology at Work

Florida’s Everglades Forever Act provided

the momentum for this success story. It

mandated and funded construction of

treatment wetlands, known as Stormwater

Treatment Areas (STAs). At present, more

than 41,000 acres of land south of Lake

Okeechobee have been converted to STAs.

In western Palm Beach County, STA-3/4, at

almost 17,000 acres, is the largest constructed wetland in the world. And more

STAs are on the way: 5,000 acres of treatment wetlands were recently added to the

existing STAs, and an additional 13,000

acres of treatment wetlands will be constructed in the coming years. 

Everglades Stormwater Treatment Areas

use “green” technology to remove phosphorus from the water. Wetland plants,

such as cattail, southern naiad and algae,

uptake phosphorus and use it in metabolic life processes. Some is also stored in

their stems and leaves. Even after the

plants die, sediments in the wetland retain

phosphorus from the decaying plant matter. As a result, water flowing out of an

STA has significantly less phosphorus

than stormwater runoff flowing in.

STAs in Key Locations

By building STAs in key locations north of

the Everglades, phosphorus in stormwater

runoff can be reduced before it flows south

into protected wetlands. The South Florida

Water Management District’s regional

canal system brings water to the treatment

wetlands and then carries it into the Everglades. The map (on back) shows the location of existing STAs, major District canals

and the STA expansions.

Meeting Mandated Goals for

Reducing Phosphorus

The Everglades Forever Act and other legal

requirements provided the District with

specific guidelines to improve Everglades

water quality. One key component was the

Everglades Construction Project, which

provided for construction of the six STAs

now in operation. Other mandated

requirements included interim and longterm target concentrations for reducing

phosphorus. At most locations throughout

the Everglades, the long-term target concentration of 10 parts per billion (ppb) of

phosphorus is already being met.

In 2003, the Florida Legislature adopted

further strategies for achieving the longterm Everglades water quality goals.

Known as the Long-Term Plan, these

strategies provide for structural and vegetation enhancements to the STAs, as well

as the STA expansions now being implemented. Collectively, these initiatives are

providing significant water quality

improvements to Everglades-bound

waters.

Stormwater Treatment Areas

use “green” technology to

remove excess phosphorus, a

nutrient that can harm the

Everglades environment.

Aerial rice planting helps stabilize wetland

soils after hurricane damage.

Collecting and analyzing water samples is

vital to wetland management.
Wildlife in the Wetlands

Stormwater Treatment Areas are built specifically for improving Everglades water quality.

However, their vast, shallow waters and rich

plant life also make them outstanding habitat

for Florida wildlife. 

Wading birds, ducks and American alligators

are found year-round in the treatment wetlands. Migratory birds use them, too, visiting

in abundance during winter months. Rabbits,

wild hogs, deer and the occasional Florida

panther roam the banks and levees.

Because the STAs have a specialized cleansing

function, public recreation is limited to activities that do not disturb the water and soils.

Guided visitors can enjoy bird watching, and

some hunting is allowed, under guidelines of

the Florida Fish and Wildlife Conservation

Commission. 

Keeping the treatment wetlands healthy and

undisturbed is vital for Everglades restoration.

Enhanced wildlife habitat is a great bonus!

Operating & Maintaining an STA

Keeping an STA performing at peak efficiency is not simple. It is a living wetland,

affected by natural conditions such as weather (rainfall, drought, hurricanes), plant

growth rates and invasion of undesirable plant species. STAs have never before been

used on the large scale now at work in the Everglades, so their operation and management is a process of ongoing learning and continual improvement

Water quantity and water quality monitoring is a vital part of STA operations. Each treatment cell is monitored regularly to determine how the STA is performing. Operational

decisions are then based on real-time data. STA performance data are continually

assessed and are reported monthly and yearly. An annual summary of STA performance

is also available in the annual South Florida Environmental Report, viewable online at

www.sfwmd.gov/sfer. 

Structural components of the STAs must be operated and maintained as well. These

include more than a dozen pump stations, 200+ water control structures and more than

100 miles each of levees and canals. Mechanical repairs, preventative maintenance, erosion control and debris cleanup are essential and ongoing tasks that must be budgeted

for and scheduled each year.

Responding to the unexpected is a large part of the job, too. In 2005, hurricane winds

tore up much of the aquatic vegetation in the STAs and stirred up the STAs’ phosphorusladen sediments. Repairing these living wetlands presented many challenges. Fortunately, scientific research and experience gained through many years of managing the

STAs were used effectively to expedite recovery. One example was to plant rice in several

of the STA treatment cells. This quick-growing plant stabilized the soil and allowed

essential aquatic vegetation, such as naiad and pondweed, to reestablish in the wetlands. 

Sustainability for the Future

Protecting Everglades water quality is a long-term commitment, and STAs will continue

to play a vital role in this effort. Sustaining their effectiveness is essential. Ongoing

research is uncovering new ways to maintain healthy plant communities and manage

sediment buildup. The State of Florida and the South Florida Water Management District

remain committed to achieving optimum phosphorus-reducing results. 

Great egret

American alligator
The South Florida Water Management District is a regional, governmental

agency that oversees the water resources in the southern half of the state. It is the

oldest and largest of the state’s five water management districts.

Our Mission is to manage and protect water resources of the region by balancing

and improving water quality, flood control, natural systems and water supply.

EN07/01/07

DID YOU KNOW?

■ Phosphorus concentrations in

water flowing into the STAs are

more than 100 parts per billion

(ppb). Outflow concentrations are

less than 50 ppb.

■ Plants that cleanse water in

Stormwater Treatment Areas

include cattail, spikerush, water

hyacinth and algae.

■ Vegetation management is vital to

STA success. Some herbicides are

used to prevent invasive species

from crowding out native plants.

■ Treatment wetlands are also used

in other parts of South Florida to

improve water quality. North and

east of Lake Okeechobee, treatment

wetlands remove nutrients from

water flowing into the lake, St.

Lucie estuary and Indian River

Lagoon.

■ Birds found in the treatment

wetlands include roseate

spoonbills, whistling ducks, white

storks, little blue herons, eagles

and hawks.

Feeder

Canal

Basin

Holey 

Land

 Canal

Miami

North New 

River Canal

Hillsboro Canal

West Palm 

Beach Canal

L-8 Borrow Canal

Ocean Canal C-51 Canal

Rotenberger

West

Palm

Beach

Fort

Lauderdale

(Arthur R. Marshall

Loxahatchee National

Wildlife Refuge)

C-139

Basin

Water

Conservation

Area 1

C

B

B

A-2

A-1

Lake Okeechobee

Atlantic Ocean

L-28

Basin

STA-3/4

STA-5

STA-2

STA-1W

STA-1E

STA-6

Water

Conservation

Area 2A

Water

Conservation

Area 2B

Water

Conservation

Area 3A

Everglades Protection Area

Everglades Protection Area

Everglades Agricultural Area

Everglades Agricultural Area Wildlife Mgmt. Area

Wildlife 

Mgmt. Area

Locator map for Everglades Stormwater Treatment Areas.

Annual reporting on

performance of the

Stormwater Treatment Areas

is found in the South Florida

Environmental Report,

available online at

www.sfwmd.gov/sfer

Up-to-date information about STA

research, enhancement projects,

details of the Long-Term Plan and

other components of managing

and improving the Stormwater

Treatment Areas can be found at

www.sfwmd.gov/sta

South Florida Water Management District

3301 Gun Club Road

West Palm Beach, Florida 33406

561-686-8800 • FL WATS 800-432-2045

www.sfwmd.gov

MAILING ADDRESS: P.O. Box 24680

West Palm Beach, FL 33416-4680