South Florida's annual rainy season typically lasts from June through October, 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 ago 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 8.1 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.
During dry periods, the Corps may also release fresh water from Lake Okeechobee to help maintain appropriate salinity levels in the Caloosahatchee Estuary. In their advisory capacity, SFWMD water managers use a guidance document known as Adaptive Protocols to make recommendations to the Corps on lake operations in these situations.
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. In spring 2013, the Corps' Jacksonville District completed construction of a cutoff wall in the dike's most vulnerable area, a 22-mile section between Port Mayaca and Belle Glade. Work is also underway 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.
Sending more water south from Lake Okeechobee is physically limited by the capacity of South Florida's flood control system of canals and water control structures. This system was built many decades ago to send excess Lake Okeechobee water east and west to the coasts instead of south to the Everglades.
Further, sending nutrient-rich water south risks harming Everglades water quality, potentially violating federal court orders.
Sending more water south into the Stormwater Treatment Areas (STAs) risks damaging their ability to perform as treatment wetlands and could violate state and federal regulations.
Sending more water south into the three Water Conservation Areas jeopardizes flood control for Broward and Miami-Dade residents and can cause damage to habitat and wildlife.
In addition, federal regulations that protect endangered wildlife, such as the Endangered Species Act and the Migratory Bird Treaty Act, prohibit certain operations that could increase flows south.
In making its management decisions for lake releases, the U.S. Army Corps of Engineers must balance flood control, public safety around the lake's Herbert Hoover Dike, navigation and water supply — in addition to considering impacts to the estuaries. Because Lake Okeechobee's water level can rise up to six times faster than water can be released through the canal system, large-volume lake releases are sometimes required, as we saw in the summer of 2013 and its historic rainfall.
Vast tracts of land plus massive pumps and water control structures would be needed to build a flow-way south of Lake Okeechobee — a multibillion-dollar effort. Science and modeling show that the Central Everglades Planning Project accomplishes the same goal of sending more water south and providing relief to the estuaries — in a more achievable and cost-effective way.
The scale of ecosystem restoration in South Florida is one of the largest environmental restoration efforts in the world. Achieving the right water quality and water quantity in the right locations with the right timing is the ultimate goal. This is complicated by factors such as unpredictable weather — including extreme rainfall or prolonged drought — and by policy issues that determine where funding and projects are needed most.
South Florida's environment has the benefit of many caring and involved stakeholders. To ultimately be successful, restoration must be a cooperative effort among many partners.