What are Lake Okeechobee discharges? Risks include water pollution and toxic algae blooms
Whether you're new to the Treasure Coast or just started paying attention to the water pollution crisis, this explanation of Lake Okeechobee discharges will help you understand this vast, complex and century-old problem.
It centers on two dams the Army Corps of Engineers opens and closes throughout the year, which can poison Treasure Coast waters with Lake O water that can contain pollutants and toxic algae.
Toxic algae blooms can pose short- and long-term health risks to people and pets, and the freshwater can kill salt-loving marine plants and animals.
What are Lake Okeechobee discharges?
Lake O fills with rainfall and runoff from the Kissimmee River watershed that stretches from Orlando to Okeechobee. Historically, excess water naturally overflowed south to the Everglades — until people developed farms, homesteads and towns that blocked the flow. To make matters worse, they built the first earthen dams around the lake in 1915.
After hurricanes in 1926 and 1928 breached those dams and drowned over 2,500 people, the Army Corps used sand, rock, gravel, shells and limestone to build better dams from 1932-1938. Since the 1960s, the agency has been expanding, raising, widening and strengthening those dams into today's Herbert Hoover Dike, which is 143 miles around the lake, 34 feet tall and 200 feet wide at its base.
The Everglades Agricultural Area is where the agency is building the EAA reservoir to capture, clean and release most excess lake water into the Everglades — as nature intended.
But where has excess lake water been going for the past 100 years? That is the root of the problem.
Port Mayaca dam to St. Lucie dam
When Lake O rises, the agency opens the Port Mayaca dam (S308) on the east side of Lake O to release water into the C-44 Canal, also called the St. Lucie Canal. Built from 1916-24, the gravity-system canal runs 23 miles, past Indiantown and to the St. Lucie dam (S80) in Stuart, adjacent to the Martin County-owned Phipps Park west of Kanner Highway.
On the west side of Lake O, the agency releases water into the C-43 Canal by opening two dams — Julian Keen (S77) and Ortona (S78) — and then into the Caloosahatchee River in Fort Myers by opening the Franklin dam (S79).
The C-43 and C-44 canals form the Okeechobee Waterway that runs from the Atlantic Ocean in Stuart to the Gulf of Mexico in Fort Myers. The locks open to move boats through. The dams open to move water through.
The agency historically has wanted Lake O's level to be about 12.5 by June 1, the start of the hurricane season, to make room for heavy summer rains. An Orlando-area storm can deluge Lake O six times faster than the agency can release it.
Under the new Lake O management plan the agency is currently writing, called the Lake Okeecobee System Operating Manual (or LOSOM), the St. Lucie River will get zero lake discharges unless the lake rises above 16.5 feet. "Send it South" is the refrain of Treasure Coast clean-water advocates who want zero lake discharges — period.
The Miccosukee Tribe in the Alligator Alley Reservation and Big Cypress National Preserve want the same. But they insist on clean water — with less than 10 parts per billion of phosphorus — to protect their land, wildlife and drinking water.
Toxic harmful algal blooms
Lake O's natural algae increases in summer because more intense sunlight over longer days allows more photosynthesis. The problem is it feasts on nitrogen and phosphorus in the rainfall runoff from Orlando-area farms and development. Blooms can be toxic, deform fish, and suck oxygen out of the water.
The "blue-green algae" — technically a cyanobacteria and most commonly the microscystis aeruginosa species — is hazardous for people, pets and wildlife to touch, ingest or inhale when it contains over 8 parts per billion of the toxin microcystin, the Environmental Protection Agency says.
Lake O water can carry or spark toxic algae blooms in the C-44 Canal, St. Lucie River, Indian River Lagoon, St. Lucie Inlet and Atlantic Ocean. Guacamole-thick, putrid-smelling algae, which contains ammonia and hydrogen sulfide, slimed the Treasure Coast during the "Lost Summers" of 2005, 2013, 2016 and 2018.
In 2016, the first and only time in recent history that toxic algae fouled the beaches, Martin and St. Lucie waterfront hotels and restaurants closed over the lucrative Fourth of July holiday.
In 2018, emergency rooms reported an increase in people complaining of nausea, vomiting, skin rashes, coughing, shortness of breath and achy limbs and joints. A Stuart vet suspects algae killed one dog and sickened five others. A study found 28 cyanobacteria species, which means more potential toxins.
Researchers are conducting myriad studies on the short- and long-term health effects. So far, they've linked it to liver disease and the BMAA toxin, which is suspected of causing neurological ailments such as Parkinson's, Alzheimer's and amyotrophic lateral sclerosis, commonly called ALS or Lou Gehrig's disease.
Scroll down for links to stories about the results of multiple studies.
Lake O discharges in spring 1998, 2010 and 2012 — before algae had formed in the lake — still caused problems from too much freshwater. In 1998, fish lost their protective outer coatings, which caused lesions and other deformities. In 2013, practically all the oysters in the St. Lucie estuary died.
C-44 Canal from Lake O to Stuart
The C-44 Canal's water level poses issues of its own. When it's too low (below 14 feet), the agency opens the Port Mayaca dam and releases water into the canal for several reasons:
Martin County farmers need irrigation water for their crops.
South Florida municipalities need drinking water for their residents.
Boaters need a 14-foot minimum canal level to navigate safely through the locks.
Stormwater treatment areas need more water in the dry season to function properly.
When the canal level's too high (over 14.5 feet), the agency opens the St. Lucie dam and releases water into the St. Lucie River in Stuart. On rare occasions, it allows water to flow back into Lake O.
The canal rises for two reasons: Lake O discharges and/or rainfall runoff in the C-44 basin, mostly from farms in western Martin County. The distinction between the two sources of water is important because they cause different environmental problems.
Lake O water poses three major issues:
It is freshwater that can kill salt-loving marine plants and animals, such as oysters and seagrasses. The latter is the main food source for manatees, and protective nurseries for fish and other species.
Toxic algae blooms can flow from the lake to the ocean.
Algae that hasn't bloomed can do so when it flows into the canal or river and feasts on the nitrogen and phosphorus in those waterways. The primary source of that pollution is fertilizer washing off farms. Agricultural interests inaccurately blame secondary sources such as lawn fertilizer and leaky septic tanks, but scientists concur, only Lake O discharges spark algae blooms in the canal and river.
Rainfall runoff poses two major issues:
It is also freshwater that can kill marine plants and animals.
It can contain enteric bacteria, which inhabit the intestinal tracts of people and animals. The fecal pollution comes from pets, wildlife, livestock and human sewage. If touched or ingested, it can cause an upset stomach, diarrhea, eye irritation and skin rashes. TCPalm tracks real-time bacteria counts and health advisories at data.tcpalm.com/beach-water-quality.
The Army Corps built the C-44 Reservoir near Indiantown, and the SFWMD is building the C-43 Reservoir near LaBelle to store, clean and move Lake O water south to the Everglades instead of discharging it east and west. Both have had construction and operation issues.
The Army Corps is also building the EAA reservoir to hold 78.2 billion gallons of water. That's not enough to stop all discharges, but is estimated to curb them by 63% when combined with all other water-storage projects.
TOXIC ALGAE STUDIES
CDC needs more volunteers to study how toxic algae enters the body, affects organs
People in toxic algae areas are more likely to die from nonalcoholic liver disease
TCPalm reporters Ed Killer and Katie Delk and former reporters Tyler Treadway and Max Chesnes contributed to this report.
This article originally appeared on Treasure Coast Newspapers: What are Lake Okeechobee discharges to the St. Lucie River?
