Other problems of Lake Okeechobee and its Watershed

As noted in the Science section above, canals and water control structures now connect Lake Okeechobee with the Caloosahatchee and St. Lucie Rivers, as well as with their estuaries. (The C-43 Canal connects Lake Okeechobee to the Caloosahatchee River and the C-44 Canal connects the Lake to the St. Lucie River. The largest water control structure for the Caloosahatchee River is the Franklin Lock (S-79), while the largest for the St. Lucie is the St. Lucie Lock (S-80) )

This connection is problematic since the C&SF structures often release too much or too little freshwater into these estuaries. According to technical documents produced by the SFWMD in 2000, the Caloosahatchee Estuary should ideally receive freshwater inflows of 300 to 2,800 cubic feet per second (cfs) to maintain optimal salinity, and to sustain the commercially important fish species that use the estuary as a nursery ground. (Species that use the area include grouper, snapper, and spotted sea trout). Maintaining sufficient flows in the Caloosahatchee is also important for water supply in the Lower West Coast-when water levels in the River get too low, saltwater intrusion can occur in the Lower West Coast Aquifer system-and for the maintenance of endangered species (such as the West Indian Manatee), resident and migratory birds. The Caloosahatchee estuary region has been identified by the Florida Fish and Wildlife Conservation Commission as "possibly the most important area in Florida in terms of maintaining several wide-ranging species that make up an important component of the wildlife diversity in the state."


During the period January 1998-June 1999, flows from the S-79 ranged from a low of 0 cfs to a high of 17,283 cfs (more than 6 times the optimal flow levels for this estuary). These outflows altered salinity in the Caloosahatchee estuary, which has been called the "master ecological variable" controlling all aspects of the estuary's productivity, community structure, food web, predator-prey structure, and population distribution. They also transported significant quantities of sediment into the estuary, and altered its turbidity, oxygen content, nutrient loads and concentration of toxins. Although the impact of these conditions varied widely across the estuary, they have broadly been associated with significant decreases in submerged aquatic vegetation south of Shell Point, emigration of finfish and mortality of non-mobile benthic (bottom-dwelling) invertebrates.

The St. Lucie Estuary should ideally receive inflows of 350 cfs to 2,000 cfs to protect its valuable oyster bars, seagrass beds, fish, and invertebrate communities. During the period December 1997 to April 1998, releases into the estuary through the C-44 Canal ranged from 2,500 cfs to 7,000 cfs. These outflows radically altered salinity concentrations in the estuary, and produced lesions on approximately 33 species of fish. They also generate a great deal of concern among local citizens, who worried about the effects of these releases on human health. Although water managers assert that the actual cause of the epidemic of lesioned fish is still unknown, scientists theorize that the impacts are directly connected to heavy freshwater discharges, and to the nutrient loads within those discharges.

During the Managed Recession of 2000, approximately one foot of water (approximately 400,000 acre-feet , which translates into more than 130 billion gallons) was intentionally released into the estuaries to mitigate adverse impacts of sustained high water in the Lake. Discharges into the St. Lucie estuary during this Recession, which lasted 27 days in April and May, 2000, flushed all salt water from the South Fork and raised turbidity levels there to four times their normal level. Field tests of oyster beds in the vicinity of these discharges suggested that oysters could not survive those conditions. Discharges to the Caloosahatchee Estuary during the Recession killed seagrasses in the lower estuary and discharged so many nutrients that intense algal blooms grew there between May 5 and June 14th. Blooms were so severe that the routinely scheduled discharges to the estuary after the Recession were stopped on June 2nd.


The Florida Oceanographic Society, a non-profit organization founded in 1964 to support the study of marine sciences and to disseminate information to the public, has monitored water quality in the St. Lucie estuary since 1998. Using data collected weekly from 9 stations in the river and estuary, the Society assigns "grades" to the outflows into the C-44 Canal from the S-80 on the basis of five parameters that are critical to biological organisms and processes: water temperature, pH, water visibility, salinity, and dissolved oxygen. Although the Society has not produced a narrative analysis of their 1998-2003 data, graphical representations of that data show a high correlation between increased discharges from the C-44 Canal and decreased estuary water quality. Between the period July 15 and October 29, 2002, for example, when massive discharges from the C-44 Canal occurred, the Estuary received an "F" rating for water quality during the entire period of the discharge.

Data from Florida's Department of Environmental Protection (DEP), the Florida Marine Research Institute and the Florida Fish and Wildlife Conservation Commission (FWC) also display strong, direct correlations between St. Lucie Canal discharges and adverse estuary impacts, notably diseased fish. DEP compared outflows from the S-80 between 1967 and 1998 and found "strong correlations" between periods of high discharge (more than 7,000 cfs) and incidents of lesioned fish in the estuary in 1980, 1983, 1995, and 1998. The Florida Marine Research Institute and FWC mapped the volume of water flows from the S-80 and the incidence of fish lesions between January 1998 and June 1, 2000. The two graphs repeatedly peaked at about the same time, which illustrated that there is a direct linkage between increased Canal outflows and diseased fish.

The FWC has also established linkages between excessive releases into the Caloosahatchee and manatee mortality. Because these releases destroy submerged aquatic vegetation consumed by manatees, and because the estuary is near manatee thermal refuges, the discharges reduce available food for manatees and force them to travel further in search of forage. Increased movement enhances the potential for manatee mortality via collision with boats or entrapment in water control structures.

The development of Minimum Flows and Levels in recent years attempts to mitigate these ill-impacts for the estuaries and for the Lake itself, as is discussed more fully in the Restoration section. More comprehensive, long-term solutions to these problems are expected in the longer term via the Comprehensive Everglades Restoration plan (CERP), which is also discussed in the Restoration section.

According to a 1994 study by J. Beacham Furse and Donald D. Fox, the EAA consumes about 1.8 million acre-feet of water from Lake Okeechobee each year. Because the same area generates $880 million in agricultural produce, each acre-foot has an economic value of approximately $500 to EAA farmers. Using this figure, one can extrapolate the economic value (to the EAA) of the 2 foot increase in Lake levels that was instituted in 1978 - with ill effects for the ecology of Lake Okeechobee. Since the SFWMD has said that a decrease in lake levels by one foot (during the Managed Recession) resulted in outflows of 400,000 acre-feet, a two foot increase in water levels since 1978 would translate into approximately 800,000 acre-feet of additional water storage each year. If each acre-foot was worth approximately $500 to EAA farmers, this increase in water depth would be valued at $400 million annually (500$/ acre-foot X 800,000 acre-feet ) to EAA farmers. Since EAA farmers vote, and Okeechobee's fish, wildlife, and submerged plants do not, it is easy to understand why the needs of agriculture, and not the needs of the Lake's ecosystem, receive greater emphasis in the eyes of Florida's politicians, and of the political appointees that staff the Governing Board of the SFWMD.


FOR MORE INFORMATION ON THE THREATS TO LAKE OKEECHOBEE SEE:

Three SFWMD factsheets on programs to reduce phosphorus: http://www.sfwmd.gov/org/wrp/wrp_okee/projects/factsheet.pdf
http://www.sfwmd.gov/org/wrp/wrp_okee/projects/lakeoalt.pdf
http://www.sfwmd.gov/org/wrp/wrp_okee/projects/lakeo_p_study.pdf
http://glacier.sfwmd.gov/org/wrp/wrp_okee/projects/lakeo_eval_alt_p.pdf

SFWMD's webpage on in-lake conditions and programs designed to address them.

SFWMD's webpage on Lake Okeechobee watershed conditions and programs designed to address them.

The Lake Okeechobee Surface Water Improvement and Management (SWIM) Plan

The Lake Okeechobee Action Plan (1999).

The Lake Okeechobee Protection Program Exotic Species Plan (June, 2001)

SFWMD's map showing priority basins (for phosphorus reductions).

SFWMD's map showing priority basins (for reduction of phosphorus).
[NOTE: this map does not indicate amount of phosphorus currently coming from each of these basins.

DEP fact sheet on the ecosystem.

Duke University Wetland Center webpage on the Central and Southern Florida Project for Flood Control and Other Purposes
This contains information on the principal threats to the Everglades ecosystem.