Restoring correct water flow in the Everglades is of vital importance
Red tide; millions of dead rotting fish cover the shoreline. A massive bloom of toxic neon-green algae; millions of tourist revenues lost. Retreating mangrove estuaries; leave coastal communities more vulnerable to storms. Fresh drinking water for 8 million people; in jeopardy. Habitat loss for plants and animals. Possible extinction of the Florida Panther. Everglades National Park ecosystem is threatened and one of the national parks most infected with invasive species.
An underwater plateau of land existed in the southernmost portion of the eastern United States since archaic times when the continents occupied different positions on the planet. Submerged beneath the ocean for thousands of years, coral, shellfish and fish skeletons piled up. This created a layer of limestone over hundreds of feet thick. As glaciers in the north expanded and melted the Florida peninsula emerged and submerged with rising or retreating sea levels. At this time the ancient Appalachian Mountains were eroding. Silt and quartz sands were carried south by streams and rivers to blanket the Florida peninsula. In the south central area of the peninsula a large geological basin existed. Until about 6,000 years ago the basin was dry. A layer of silt built up that compacted more than the underlying sand and limestone. Slowly water accumulated in the basin, eventually forming Lake Okeechobee, the third largest freshwater lake in the country.
The Okeechobee Basin played a defining role in formation of the Everglades ecosystem and is still as important as ever. It is the water from Lake Okeechobee that replenishes aquifers and trickles southward through a sawgrass prairie to the sea. During the summer rainy season, fresh water overflows the south shore of Lake Okeechobee and flows in a sheet about 100 miles long, dropping only 12 ft. to 14 ft. in elevation, to reach the terminus in Florida Bay.
In freshwater sawgrass marshland and salty mangroves of the Everglades, organic soils (called peat soils) develop under persistent flooding. Peat soils are comprised of plant material that accumulates faster than it can decompose. About 5,000 years ago peat soil began to accumulate from the remains of aquatic plants preserved in the waterlogged conditions. In the deepest freshwater marshes peat soils are 2 ft. to 3 ft. in thickness. In Everglade mangroves, peat soils thickness can exceed 10 ft.
In the early years of the 20th century southern Florida was seeing an unprecedented surge in population, real estate development and land speculation. At the time, draining of Everglades swamp land was seen as a progressive movement that would open virgin land for agriculture, oil and gas exploration and provide for urban development. Canals, ditches, dams and levees were constructed to redirect waters flowing from Lake Okeechobee. The Everglade habitats were segmented and natural occurring cycles were being altered. Raised roadbeds, like the Tamiami Trail that crosses the heart of the Everglades, dammed the low relief slow moving sheet flow of water.
In 2000, the United States Congress passed the Comprehensive Everglades Restoration Plan (CERP), which forced both federal and state officials to develop a plan to route water south to refresh stagnant swampland in southwest Florida.
Everglades National Park is recognized as a World Heritage Site. In 2017 the International Union for Conservation of Nature (INCN) issued a report on the health of the Everglade bioregion. These are their findings.
- Conservation Outlook: Critical. Unless more restoration projects outside the site to deliver more clean water to the site as correctly timed sheetflow, and are not compromised the essential qualities and habitat will continue to be lost.
- Values: Critical. Water quantity, quality, distribution and timing are deteriorating. Invasive species and climate change is creating overriding impacts to the system and the deteriorating trend of so many values puts the parks World Heritage values in a critical situation.
- Overall Threats: Very High Threat. Reduced water flows, water pollution and shifting habitat threats include hurricanes, climate change and ocean acidification.
The Everglades is the most significant breeding ground for wading birds in the United States. It is also provides habitat for a number of species found no place else on Earth and it also provides fresh drinking water for over 8 million people. Mostly due to past human activity The entire Everglades ecosystem is severely threatened.
The Everglades bioregion is suffering from a barrage of pressures. Invasive species is one of them. The most successful invaders out compete native species and typically have few biological controls to keep them in check. Over the last decade, snakes from around the world have been turning up in Everglades National Park. The Burmese Python is the best known and most problematic of these snakes. Mammal population numbers have declined sharply in the park as a result. Non-native reptiles, amphibians, birds, mammals, fresh and saltwater fish species have all invaded and now make the Everglades home.
In terms of exotic plants, Everglades National Park is severely infected. Brazilian Pepper is the most serious long term threat. Other invasive plant species such as Melaleuca, Australian Pine, Seaside Mahoe, Leather Leaf and Old World Climbing Fern have also established themselves in the park. Because of limited funding only a small number of the exotic plant species can be targeted for treatment.
Threatened and Endangered
The United States Congress established the Endangered Species Act (ESA) in 1973 to provide a framework to conserve and protect endangered and threatened species and their habitats. The Endangered Species Act is a key legislation for both domestic and international conservation.
In the listing of plant and animal species the Endangered Species Act uses the term Threatened to indicate the species is likely to become endangered and the term Endangered to mean in immediate danger of extinction.
Threatened and endangered plant life of hardwood hammocks and rocky pinelands in the Everglades include: Brittle Thatch Palm, Buccaneer Palm, Florida Thatch Palm, Krug’s Holly, Lignum-Vitae, Manchineel, Silver Thatch Palm and Tree Cactus.
Marine and estuarine regions of the Everglades provide habitat for Florida’s population of Green Sea Turtles. Green Sea Turtles have been listed as endangered since 1978. The declining population is attributed to commercial harvesting for eggs and food as well as incidental bycatch in fishing and shrimp nets. Hawksbill Turtle, Atlantic Ridley Turtle and Leatherback Turtle are listed as endangered and Loggerhead Turtles as threatened.
Bird species listed are: Everglades Snail Kite, Woodstork, Cape Sable Seaside Sparrow, Red-cockaided Woodpecker, Piping Plover, Bald Eagle and Roseate Tern.
The Florida Manatee is listed as endangered.
The only known breeding area for the Florida Panther is in Big Cypress Swamp. The Florida Panther is one of the most endangered species in the world. Loss and degradation of habitat has doomed the panther population. There are only 70 to 100 that remain. Note; While I was visiting southwest Florida in February 2019, it was reported that two Florida Panthers had died, due to being struck by vehicles on the Tamiami Trail in the region of Big Cypress Swamp.
Mangroves are made up of coastal vegetation that grows in salty or brackish water. They are considered crucial buffers to storms and saltwater intrusion, as well as key habitats for certain marine creatures. Mangroves filter pollution, hold nutrients and provide food and nesting. Florida’s mangroves are a vital part of the ecosystem.
Mangrove forests are retreating inland, leaving behind open water and imperiling coastal communities. Researchers collected sediment cores from mangroves and analyzed aerial photographs and satellite imagery taken over the years. What they discovered was that mangroves south of Miami were retreating about 100 ft. a year. According to the study, this trend is related to salt water intrusion caused by sea level rise and water management practices.
The Florida Oceans and Coastal Council in Tallahassee, Florida is studying the consequences of mangroves retreating from coastal areas. They have addressed their concerns as follows:
- Changes in barrier islands, beaches and inlets.
- Changes in estuaries, tidal rivers and coastal forests.
- Higher storm surge and impacts on coastal infrastructure.
- Threats to coastal water supply and waste water treatment.
- Increase in beach erosion and renourishment.
- Impacts on coastal planning.
- Increased flooding risks.
Nearly 8 million people depend on the Everglades for drinking water. The Biscayne Aquifer is located just below the land surface in southeast Florida. The aquifer sits atop a highly permeable layer of limestone and covers approximately 4,000 sq. miles, underlying Broward County, Miami-Dade County, Monroe County and Palm Beach County. Most of south Florida residents, visitors and businesses are dependant on water from the aquifer. Because the Biscayne Aquifer is so close to the surface it is extremely vulnerable to surface contamination.
When developers built out Miami-Dade it was often less costly to install individual septic tanks to new homes rather than wait for municipal infrastructure to catch up with sewage treatment lines. In southeast Florida groundwater is especially close to the surface. Since the 1960s, the amount of precipitation that falls during the heaviest of storms has increased. Miami Beach and Key Biscayne are often inundated. More intense flooding and rain storms that swell the water table are sending partially treated human waste into the aquifer.
Miami Drum Services company operated within a few blocks of an aquifer well head in Miami-Dade County for over a decade. In 1981 the business was forced closed for pollution warnings. Miami Drum Services became a Superfund site. The E.P.A. later said the space was leaching arsenic, cyanide, mercury, nickel, lead, cadmium, chloroform and oil into the groundwater.
Increased flooding can dislodge the toxic chemicals that remain in Superfund and other industrial sites, pushing them into the Biscayne Aquifer.
As the ocean rises, salt water is being pushed into the limestone substrate and is creeping inland. As the saltwater advances westward across the aquifer it will reach wellhead intake valves enveloping them in saltwater, rendering them useless.
Because rainfall contributes most of the water, soils and water in the Everglades are low in nutrients, especially phosphorus. Plants and animals that colonized the area became well adapted to survive in a low-nutrient, freshwater habitat. Farmers in agricultural areas cultivated their crops in peat soils to allow their crops to flourish.
To expand productive agricultural land a network of canals were dredged to drain surface water. When we deprive marshes of freshwater, peat soils breakdown, resulting in soil loss. Once exposed to air, drained soils are gradually oxidised away by aerobic bacteria. As much as 2/3 rds of past productive peat soil has been lost because of water drainage programs.
In addition to draining soils, farmers also fertilized the land. Over the years a variety of chemicals have been added to the Everglades agricultural area.
In the mid-1980s scientists reported problems with eutrophication in Lake Okeechobee. Eutrophication results in rapid overgrowth of plant and algal species due to excessive nutrients. In 1988, federal, state and agricultural interests agreed on an approach to reduce phosphorus levels entering the waterway. By 1992 phosphorus levels had dropped from 150 ppb to 30 ppb, a significant achievement. The goal is further reduction of phosphorus to 10 ppb which would resemble naturally occurring levels. The goal may not be achievable. A massive algal bloom invaded southwest Florida in 2018 with devastating effects
Salt Water Intrusion
Saltwater can encroach coastal areas as a result of development. Some of the saltwater has migrated inland in response to the lowering of inland groundwater levels adjacent to canals constructed for drainage of low lying areas and near large well fields. Construction of drainage canals lowered freshwater levels and allows landward movement of saltwater and into the aquifer. The canal becomes a tidal channel that conveys saltwater inland. Low freshwater flow (because of water management) and saltwater intrusion can change an affected area by loss of land eventually leading to the area becoming open water.
The speed at which Florida sea level has increased and is now rising as much as 1 inch every three years. In Miami-Dade County, the groundwater levels in some places are not high enough relative to rising sea levels has allowed saltwater intrusion into drinking water and compromised sewage plants. Many traditional methods to solve sea level rise and flooding in Florida won’t work, because water can flow through permeable limestone and below sea walls.
Sea Level Rise
When Congress passed the Comprehensive Everglades Restoration Plan in 2000 they did not take into account issues of sea level rise.
Everglades wetlands dip below sea level at the coast and gradually rise as you move north at a slope of about 2 inches for every mile. So, for every 2 inch increase in sea level we can expect to see about a one-mile wide strip of freshwater Everglades exposed to saltwater. The Pensacola Bay and St. Johns River watersheds and southern Florida from Palm Beach to Miami, the Florida Keys, Naples and Fort Myers are especially vulnerable to saltwater intrusion.
Sea level rise is the greatest threat to Florida’s environment, economy and culture over the coming decades. There will be unprecedented challenges for sustainability, urban planning and political action.
“Unless someone like you cares a whole awful lot, nothing is going to get better. It’s not” Dr. Suess
Restoring correct water flow in the Everglades is of vital importance.
Mālama ke Kuleana o ka ʻĀina – Hawaiian phrase for Take care of the responsibility of the land
Till next time, Dohn