SUB-REGION 2. LAKE OKEECHOBEE AND THE EAST/WEST WATERWAYS
ECOLOGICAL CHARACTERISTICS:
o Large (1732 km2; third largest lake in the U.S.), shallow (aver. depth = 2.7 m), geologically young (approx. 6,000 years old), sub-tropical Lake Okeechobee, which has been impacted by impoundment, water control structures (31) regulating lake level and water flow, and eutrophication from agriculturally derived non-point source pollution.
o Lake Okeechobee is "liquid heart" of south Florida's interconnected Kissimmee River/Lake Okeechobee/Everglades ecosystems; source of water for the remnant Everglades, Florida Bay, and the large human population on the lower east coast.
o Extensive Lake Okeechobee littoral zone (400 km2) developed in its present location after impoundment; contains a diverse community of emergent, floating-leaved, floating, and submersed macrophytes, and exotic species. The littoral zone is important nursery ground and habitat for fish, other aquatic organisms, wading birds, waterfowl, and endangered species such as the snail kite.
o Lake Okeechobee drainage basin (12,000 km2) lies mostly to north of lake; land use characterized by agriculture to north and northeast (primarily dairy and beef cattle). Everglades Agricultural Area (EAA, 280,000 ha) to south, home to multi-billion dollar sugar, rice, and winter vegetable crop.
o Lake Okeechobee total phosphorus concentrations have doubled in the last decade due to agriculturally derived phosphorus inputs. As a result, nitrogen has become limiting in certain areas of the lake, favoring blue-green algae, and blue-green blooms have increased in frequency and intensity.
o The present recreational and commercial fishery on Lake Okeechobee is diverse (black crappie, largemouth bass, bluegill, redear sunfish, and catfishes) and is a valuable contributor to the local economy (more than $100 million dollars annually).
o The east waterway from Lake Okeechobee (St. Lucie Canal, C-44) represents an artificial connection to the St. Lucie estuary; this results in frequent seasonal (6 out of 10 years, 1979-1988) flood-control releases of large volumes of freshwater and damage to estuarine organisms.
o Regulatory release methods were recently modified to reduce large slugs of damaging fresh water entering the estuaries.
o The west waterway from Lake Okeechobee (Caloosahatchee River) is an historic connection which has been enlarged and channelized; results in occasional flood-control releases of large volumes of freshwater and damage to the estuarine organisms of the Caloosahatchee River estuary.
o Large estuarine-barrier island system at mouth of Caloosahatchie River, including lower Charlotte harbor; impacted by rapidly increasing urbanization.
ECOLOGICAL RESTORATION OBJECTIVES:
o Minimally, expand Lake Okeechobee's littoral zone by 200 sq km on the northwest side and allowing for increased water levels, and consequently hydrologically integrating the Lake and the Kissimmee River. Maximum restoration requires reestablishing the total lost littoral zone present prior to drainage and flood protection works.
o Eliminate (maximum) or control (minimum) exotic species such as Melaleuca from the Lake Okeechobee littoral zone.
o Reduce nutrient inputs to Lake Okeechobee to pre-disturbance levels; restore the lake's natural trophic status and phosphorus-limited condition; reduce algal bloom frequency, intensity, and composition to natural conditions.
o Eliminate (maximum) or reduce (minimum) point and non-point sources of pollution to Lake Okeechobee to meet Class I/III water quality standards.
o Restore Lake Okeechobee water quality, basin land use characteristics, and littoral zone to pre-disturbance conditions for enhancement of wading bird, waterfowl, and threatened/endangered populations.
o Establish and maintain a recreational and commercial fishery that is consistent with the natural water quality and biological productivity of a restored Lake Okeechobee.
o Remove muck from benthic areas of Indian River Lagoon to reestablish seagrass beds and estuarine productivity.
o Integrate the islands at the southern end of the Lake into an overall management plan for the Lake.
HYDROLOGICAL OBJECTIVES:
Studies and modelling efforts are underway to provide numeric ranges for the following hydrologic objectives and should be available in 3-4 months.
o Implement a more flexible Lake Okeechobee water level regulation schedule that mimics natural hydrologic variability and enhances the expanded littoral zone ecosystem.
o Reestablish sheet-flow for all (maximum) or all regulatory (minimum) discharges from the southern portion of Lake Okeechobee to convey historic flows to the central and southern Everglades.
o Restore the natural hydrological and ecological functions of the St. Lucie and Caloosahatchee River drainage basins to eliminate the need for supplemental base flow discharges from Lake Okeechobee. Maximum freshwater discharges into the Indian River through C-23, 24 and 25 and C-44 should not exceed 2500 cfs.
o Eliminate total discharges in excess of 1500 cfs to the Caloosahatchee River from Lake Okeechobee and local basins.
o Eliminate (maximum) or eliminate regulatory (minimum) freshwater discharges from Lake Okeechobee to the St. Lucie River estuary; reduce freshwater discharges to the Caloosahatchee River estuary to pre-disturbance levels (maximum) or eliminate regulatory discharges of freshwater (minimum).
o Improve quality of discharges to estuaries, especially from adjacent urban developments, so as to meet Class III Standards.
o Freshwater inflows to the Indian River Lagoon are controlled within the envelope of 200 cfs and 2500 cfs.
CRITICAL LINKAGES:
o Restore the historical hydrological and ecological linkages between the Kissimmee River, Lake Okeechobee, and the Everglades, while maintaining flood protection and realistic water supply needs (coupled with human population growth management and water use conservation).
SUCCESS CRITERIA:
o Seasonal use of the newly restored littoral zone for feeding by wading birds; continued seasonal wading bird feeding in the presently existing littoral zone; nesting success in roughly 2 or more out of 5 years for wading bird colonies nesting in the Lake littoral zones.
o Reduction of Lake Okeechobee total phosphorus concentrations to an average, whole-lake concentration of 0.040 mg P L-1 (SFWMD 1989).
o Reestablishment of phosphorus limitation of Lake Okeechobee's phytoplankton community as indicated by phosphorus, nitrogen, and chlorophyll-based trophic state indices.
o Statistically significant reduction in long-term areal extent, intensity (as measured by chlorophyll concentrations), and frequency of blue-green algae blooms.
o Restoration of oligotrophic vegetative communities on islands and in littoral zones of the Lake.
o Recover the endangered and threatened species, including the Okeechobee Gord and Snail Kite.
o Reestablishment of all natural flow (stages, volumes, timing, location) southerly from Lake Okeechobee (maximum).
o Reestablishment of flow (stages, volumes, timing) of regulatory releases southerly from Lake Okeechobee (minimum).
o Statistically significant reduction in the relative blooms of blue-green algae, accompanied by replacement with more desirable species that do not form surface scums, and which form a quality food base for zooplankton and fish populations.
o Increased abundances and diversity in benthic and the water column communities in the St. Lucie Inlet and Lower Indian River Lagoon.
o Elimination (maximum) or control (minimum) of Melaleuca and other exotic species from Lake Okeechobee and its littoral zone.
o Compliance with Class I/III water quality standards within Lake Okeechobee and its tributaries.
o Re-establishment of seagrass in estuarine waters less than 2 meters in depth.
o Increase in estuarine presence of manatees in areas of seagrass return.
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