June is typically the first full month of South Florida's annual rainy season, a five-month period that brings 70 percent of our regional rainfall in an average year. The rainy season can also bring flooding, which may occur when large amounts of rain fall over a short period of time or from a single heavy storm, tropical system or hurricane.
If you haven't lived in Florida for long, you may not know that our climate has two seasons: wet and dry. Flood and drought are frequent visitors, the result of too much or too little rain. In any year, drought can happen during the wet season, and flooding can occur when we least expect a downpour. Weather in South Florida has a way of ignoring the calendar and expectations of "normal."
A Shared Responsibility
The South Florida Water Management District operates and maintains the regional water management system known as the Central and Southern Florida Project, which was authorized by Congress more than 60 years to protect residents and businesses from floods and droughts. This primary system of canals and natural waterways connects to community drainage districts and hundreds of smaller neighborhood systems to effectively manage floodwaters during heavy rain.
As a result of this interconnected drainage system, flood control in South Florida is a shared responsibility between the District, county and city governments, local drainage districts, homeowners associations and residents.
At the heart of the greater Everglades ecosystem, Lake Okeechobee historically overflowed its banks, sending a sheet flow of water south through the Everglades. Today, the 730-square-mile lake is part of a massive flood control system known as the Central & Southern Florida Project, which stretches from just south of Orlando to Florida Bay and serves 7.7 million people.
The U.S. Army Corps of Engineers manages Lake Okeechobee water levels with the goal of balancing flood control, public safety, navigation, water supply and ecological health. The Corps bases operational decisions – whether to retain or release water in the massive lake – on its regulation schedule and the best available science and data provided by its staff and a variety of partners, including the South Florida Water Management District.
Under its revised 2008 regulation schedule, the Corps strives to maintain Lake Okeechobee's water level between 12.5 feet and 15.5 feet NGVD, in part to protect the integrity of the aging Herbert Hoover Dike that surrounds the lake. The lake's water level can rise up to six times faster than water can be discharged. For example, heavy rains from Tropical Storm Isaac in August 2012 raised the lake level by 3 feet in a month.
The Corps continuously monitors the effects of any releases on the estuaries and consults with its partner agencies and stakeholders to modify releases to help minimize impacts to coastal waters.
Strategies for Increasing Water Storage and Moving Water South
The District is working with its federal, state and local partners on a variety of strategies to help minimize the need for freshwater releases from Lake Okeechobee that can cause ecological harm to the coastal estuaries. more »
These strategies are designed to increase water storage in the regional system and move more clean water south to the Everglades. They include:
Capturing more seasonal rainfall in restored sections of the Kissimmee River floodplain to more slowly – and naturally – deliver water to Lake Okeechobee.
Constructing storage features known as flow equalization basins (FEBs) south of Lake Okeechobee as part of the State's Restoration Strategies for improving water quality in the Everglades.
Working with private property owners through the District's Dispersed Water Management Program to retain water from lake discharges and regional runoff on large tracts of ranchland.
Advocating for the Corps to hold water levels higher in Lake Okeechobee for increased storage as it makes progress in rehabilitating the Herbert Hoover Dike.
Working with the Corps on the Central Everglades Planning Project to deliver a plan for restoration projects in the central Everglades that would increase the storage, treatment and movement of water south of Lake Okeechobee.
The U.S. Army Corps of Engineers manages Lake Okeechobee water levels with the goal of balancing flood control, public safety, navigation, water supply and ecological health. The Corps bases operational decisions – whether to retain or release water in the 730-square-mile lake – on its regulation schedule and the best available science and data provided by its staff and a variety of partners, including the South Florida Water Management District. Rehabilitation of the 75-year-old Herbert Hoover Dike is a Corps top safety priority. The Corps' Jacksonville District is near completion on rehabilitating the dike's most vulnerable area, a 22-mile section between Port Mayaca and Belle Glade. Work is also under way to replace or remove a series of culverts installed around the lake.
The U.S. Army Corps of Engineers may need to decrease the probability of the water level rising to an elevation that could threaten the stability of the Herbert Hoover Dike. The lake's water level can rise up to six times faster than water can be discharged. The Corps strives to maintain Lake Okeechobee's water level between 12.5 feet and 15.5 feet NGVD. By initially prescribing low-volume releases, the regulation schedule reduces the frequency of larger releases that have greater impact on receiving water bodies. However, if inflows and levels continue to increase, larger releases are required. The Corps continuously monitors the effects of direct rainfall and any releases on the primary waterways and the receiving estuaries. The Corps confers with its partner agencies and stakeholders to modify releases to help minimize impacts to waterway communities and coastal waters.
To assist the U.S. Army Corps of Engineers in furthering lake management goals, the South Florida Water Management District continues to provide unique scientific expertise and data for assessing the ecological health of Lake Okeechobee and the St. Lucie and Caloosahatchee estuaries and their surrounding ecosystems.
The District's Dispersed Water Management program works with a coalition of other agencies, environmental organizations, ranchers and researchers to enhance opportunities for storing excess surface water on private, public and tribal lands. Retaining water on these lands is one tool to reduce the amount of water that is delivered into Lake Okeechobee and discharged to coastal estuaries.
More than 130,000 acre-feet of water storage has been made available in South Florida through regional public projects and the Dispersed Water Management Program since it was launched in 2005. Planned projects that have been assessed for implementation may provide additional storage in the future, pending funding. To put this in perspective, 450,000 acre-feet of storage equates to approximately 1 foot of water off of Lake Okeechobee.
Canals are designed to convey water and do not effectively store large volumes of water. Raising canal levels alone would not lessen the need for the Corps to make regulatory releases from Lake Okeechobee. Raising water levels in 120 miles of primary canals in the Everglades Agricultural Area by 1 foot equates to approximately .01 foot of water off of Lake Okeechobee. Holding higher water levels in canals during the rainy season would also make the canals more vulnerable to flooding during heavy rains.
At times, yes. The ability to use the Everglades Water Conservation Areas (WCAs) for water storage in the rainy season is influenced by several factors: the capacity of the WCAs, the quality of the water entering the WCAs and the conveyance capacity of the canals. Water levels in the Water Conservation Areas are managed by the U.S. Army Corps of Engineers in accordance with a regulation schedule that balances flood control, public safety, water supply and ecological health. High water levels within the WCAs can jeopardize the ability to provide flood control and cause environmental damage – including the habitat and viability of endangered and threatened species. Water released from Lake Okeechobee must be treated by Stormwater Treatment Areas (STAs) to certain water quality standards before it can be moved into the Everglades. The capacity of area canals also limits the amount of water that can be moved into the WCAs.
Yes, under certain conditions. Stormwater Treatment Areas (STAs) play a vital role in protecting and restoring America's Everglades. These large constructed wetlands do provide some water storage, but they are designed for water quality purposes – to remove excess nutrients from runoff. Storing too much water in STAs limits their ability to effectively remove nutrients, such as phosphorus. When phosphorus enters the Everglades ecosystem in excess, plant growth is stimulated, producing an overabundance of undesirable vegetation.
A number of long-term restoration efforts are under way to address both water quality and limited water storage, which will also provide improved flexibility and operation of the current water management system. The Dispersed Water Management program is being expanded to create additional shallow water retention on private lands. South of the lake, the state's Restoration Strategies for providing cleaner water for the Everglades calls for the construction of new water storage impoundments and additional constructed wetlands. Planning and design is already under way on several project components.