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Summary of Warm Water Refugia Issues

The following is a synopsis of the Imperiled Species Management Section (ISM) endeavors regarding the topic of artificial warm water refuges.

The Florida Department of Environmental Protection assumed the permitting duties for the federal National Pollutant Discharge Elimination System (NPDES) in 1995. Included in this permitting process are power plants, which have warm water discharges that empty into the coastal waters of Florida. These power plants are issued permits for five-year periods. The Bureau of Water Facilities is primarily responsible for the Department's NPDES permitting. However, the permitting process requires a determination of whether a power plant provides critical manatee habitat pursuant to the Federal Manatee Recovery Plan. The Imperiled Species Management Section (ISM) and the U.S. Fish and Wildlife Service (USFWS) jointly make this determination. Those power plants identified as providing critical manatee habitat are required to create and implement an approved manatee protection plan (not to be confused with county-based manatee protection plans). These plans will address issues such as, consistency of warm water discharges, disruptions to warm water outflows during the cold season, outfall water temperatures and timely communication and coordination with state and federal agencies.

ISM has recently been faced with legitimate, complex questions regarding artificial warm water refuges and manatee use of these systems. Questions have been raised about the life span of power plants, their safety, reliability, and location:

  • Is there a long-term benefit to regional manatee populations using artificial warm water refuges
  • Have manatees benefited from artificial warm water refuges?
  • Are manatees at greater risk by wintering north of areas where we would typically expect them to be?

The intuitive answer to these questions is, "Probably." Discussions regarding these issues have been initiated by state and federal agencies as well as by the general public and effected industries.

To put these questions in perspective, a little power plant history is necessary. Many of the existing Florida power plants have been operating and discharging warm water into the coastal waters of Florida for over 30 years. During that time, manatees have gradually become habituated to wintering at these artificial warm water discharges. The number of manatees using power plant discharges has also increased during this time frame.

Research indicates that manatees often come back to the same discharge(s) year after year, and that calves may learn this routine from their mothers. Satellite telemetry has shown that some manatees know where a number of discharges are, and that they may travel from one power plant to another during the winter. Obviously, this is not the historical situation, but the winter distribution of manatees prior to the creation of these artificial warm water refuges is unknown. Many hypothesize that prior to the creation of these artificial warm water refuges the migration for manatees was more direct--north to south during the winter. It is further hypothesized that the majority of manatees gathered in extreme south Florida during the winter. However, it is also possible that manatees used natural warm water areas that over time have been lost due to human development. The presence of power plants have permitted manatees to spend the winter in areas like Brevard County and Tampa Bay, which are considered to be north of their historical range. Manatees that winter this far north are much more reliant on these refugia for survival than those manatees using a power plant in south Florida. Conceivably, manatees that habituated to artificial warm water sites in north Florida may be in greater peril in the event of a power plant failure during the cold season when compared to those manatees that initially migrated to southern Florida with the onset of winter.

During the winter of 1997-1998, cooperating state and federal agencies had the chance to initiate a research project that addressed the loss of an artificial thermal refuge in Northeast Florida. An artificial warm water discharge, on Amelia Island, was modified to meet water quality standards by moving it to deeper water, effectively eliminating its use by manatees as a warm water refuge. State and federal agencies, responsible for manatees, consented to this modification because it affected a small number of manatees and it provided a unique research opportunity. Specifically, this provided an opportunity to gain an understanding of what behavior would be exhibited by manatees when a warm water source was eliminated. When the warm water discharge was eliminated on November 10, it was anticipated that the manatees using this site would head south to known warm water refugia. Although the results of this study are still being analyzed, we do know that some tagged and untagged manatees died of what is suspected to be cold stress. Most of the animals that were known to use this site did not leave the northeast Florida and southeast Georgia area as winter approached, even though their warm water refuge had disappeared. It appears that these manatees went to secondary sites in Georgia that may not have provided adequate amounts of warm water rather than migrating south. These preliminary observations have considerable implications for manatees and their management in regard to artificial warm water discharges--especially in the northern extremes of their current winter range.

In February of 1997, some of the same issues were also raised by the Southwest Florida Marine Trade Association (SWFMTA) during their challenge of the issuance of the NPDES permit for the FPL Fort Myers power plant. In their petition the SWFMTA maintained that FDEP did not know what long-term effects the warm water discharge were having on manatees. Additionally, the SWFMTA maintained that the warm water discharge may be detrimental to manatees because it interrupted historic manatee migration patterns, it concentrates numerous manatees in a high boat use area, and close to an area with historically high incidences of red tide. This permit challenge was settled in March of 1998 (see page 10 of volume 2, issue 1 of the Manatee News Quarterly for details). One thing is apparent from this challenge and settlement, it has spurred further discussions, and potential resolutions for some of the issues surrounding manatees and their use of artificial warm water.

Other important questions and concerns also loom in the future. There is a distinct possibility that within the next five years the Florida Legislature will introduce legislation that will deregulate the power industry. With deregulation may come changes in how power is supplied by individual power plants. Although it is unclear exactly what effects this will have on manatees-it will require the power industry to be more efficient. This may mean older less efficient plants will operate inconsistently, resulting in limited warm water discharges. Interruptions in warm water outfalls during winter cold fronts may jeopardize the survival of manatees habituated to these areas. One possibility, to minimize potential adverse effects, is for State and Federal agencies to be involved in the creation of deregulation legislation. This may help to insure that manatee protection is an important consideration of any legislation that may be ratified. The Marine Mammal Commission has suggested additional ideas such as, a new network of artificial thermal refuges and/or enhancing existing secondary refuges or potential warm water sites to reduce the cold weather risks facing manatees. While these are legitimate ideas, a better understanding of manatee behavior and warm water physiological requirements is need before they can be considered as management strategies. It is of the utmost importance that before we embark on a specific course of action, we develop a strategy that is in the best interest of the manatee population's recovery and stability over the long term.

In addition to the development of the power plant protection plans for manatees, state and federal agencies have begun a series of meetings to discuss artificial warm water refuge issues and develop a long-term strategic plan. The participants of these meetings contemplated research needs and discussed the pros and cons of possible courses of actions related to warm water refuges. Future meetings are planned so a long-term strategy involving artificial warm water refugia and manatees can be developed.

While it is recognized that power plants are not natural, manatees have become dependent on their existence. Due to this documented fact, it is imperative that for the foreseeable future a power plant with significant manatee use provide a safe and consistent refuge. Without that assurance, the combination of a severe cold front and the temporary loss of a high use artificial warm water site could cause catastrophic losses to a regional manatee population. In most instances, the NPDES required manatee protection plans (developed in cooperation with the power companies) should help reduce the risk of this from happening. Finally, research is being planned by recovery team members to focus on the long-term ramifications of power plant discharges on manatees. As these issues unfold we will inform interested parties of all new information and actions.