Endangered
Florida Manatees Will Benefit From Ocklawaha Restoration
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• Rodman Dam and Buckman Lock are barriers
to the movement of manatees into the Ocklawaha River system, including Silver
Springs.
• The dam and lock are the main causes of manatee deaths in the
area.
• The restored Ocklawaha will provide ideal manatee habitat,
contributing to the survival of this endangered species.
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After
Rodman Dam is removed, the endangered Florida Manatee will once again be
allowed to follow its historical migratory pathway up the Ocklawaha River and
its tributaries and springs. The
restored Ocklawaha system will provide important habitat for this endangered
species.
Since
l968, Rodman Dam and Buckman Lock have blocked passage of manatees into the
upper reaches of the Ocklawaha River and Silver Springs. The river had been a source of food and
shelter for manatees as evidenced by sightings and manatee skeletal remains. These manatees traveled from the St. Johns
River, which is noted for its use by east coast and resident manatees. The Ocklawaha River connects Silver
Springs to other rivers and the ocean.
To
restore the Ocklawaha River, Rodman Dam (also known as Kirkpatrick Dam) will be
breached and the barge canal and Buckman Lock closed. Manatees, as well as migratory fish, will again be able to
move unhindered into the upper reaches of the river where they feed on native
aquatic vegetation and find shelter in the waters of the many springs that line
the river. According to the
environmental impact statement, 13 species of fish have been eliminated or
drastically reduced from the Ocklawaha basin by Rodman Dam. For example, large
schools of shad, mullet and striped bass were commonplace up river at Silver
Springs and are now only seen in limited numbers.
Rodman Structures Kill Manatees
According
to a l997 report by the Florida Bureau of Protected Species Management, “access to the upper Ocklawaha will be granted
to manatees only as a result of planned restoration efforts.” This
is because the dam and lock have been a significant source of manatee
mortality. Since l974, they have
crushed or drowned at least ten manatees that tried to pass through these water
control mechanisms. Closing gates
at the lock crushed three of these manatees, and the other seven were killed at
the dam where rushing water pinned them against the rocky debris and spillway
structures. An additional nine
manatees were found dead in the area, but the cause of death could not be conclusively
determined.
In
1999, Buckman Lock’s gates crushed one of the biggest manatees ever
recorded in Florida. At 2,800 pounds, she was so large the state official that
tracked her movements named her after the Greek goddess Hera. Before her death at the Rodman
Reservoir, Hera was tracked for almost a decade moving up and down the coast of
Florida and over-wintering in Blue Spring State Park on the St. Johns
River.
In
an effort to prevent more manatee deaths, U.S. Fish and Wildlife Service
required the state of Florida close the Buckman Lock until protection devices
are installed. The lock was closed February 2000 * NEED TO CHECK DATE *. Installation of an acoustic ray device at the lock and
a protection grate at the dam has cost taxpayers $1.2 million. The lock is
scheduled to be operational again before the end of 2002.
Restoration
of the Ocklawaha River will eliminate use of the Buckman Lock and Rodman Dam
structures, removing the leading cause of manatee deaths in the area. Manatees are known to move between Blue
Spring State Park and sections of the St. Johns River centered on the barge
canal. Removing Rodman Dam and closing Buckman Lock would allow manatees to
move freely into the Ocklawaha River, a significant tributary of the St. Johns,
without risk of being crushed by dam or lock structures.
Springs Habitat Can Be Regained
The
waters of Rodman Reservoir covered twenty natural artesian springs when the
Ocklawaha was impounded. After Rodman
is drained and the natural flow of the river restored, these springs will again
flow freely into the Ocklawaha, providing additional habitat and warm water
refuge for manatees.
A
recent study by the St. Johns River Water Management District indicates that
over the last 20 years spring flows in north Florida have declined by twenty
percent. The bad news for manatees
is that when decreased flow rates occur simultaneously with higher river levels
and cold temperatures, the probability increases that cold river water will
intrude on the warmer spring runs where manatees take shelter. At the current rate of decline in
spring flow, Blue Spring State Park may no longer be a reliable winter refuge
for manatees in another 20 years.
Restoration
of springs currently drowned by Rodman Reservoir would provide winter refuge
for the cold-sensitive manatee, as well as abundant food, fresh water and
shelter.
Predictions
of future manatee use of the river can best be determined by considering
surveys of manatees in the area.
In l997, 104 manatees were counted at nearby Blue Spring State Park,
compared to the 18-25 found there in the 1970s. In addition, groups of 4 to 5 manatees frequently have been
sighted trying to enter Buckman Lock, with as many as 28 counted in a single
month.
Protecting and restoring the
diminishing habitat of the endangered Florida Manatee is vital to the survival
of the species. The restored Ocklawaha River should provide ideal manatee
habitat. According to the U.S. Fish and Wildlife Service, restoration
“will have a positive effect on the conservation of the manatee.”
References:
Lefebvre, Ph.D., Lynn W.,
“Possible Significance of the Ocklawaha River to the Florida
Manatee,” U.S. Fish and Wildlife Service. *ADD YEAR*
Smith, Kent. The Effects
of Restoration of the Ocklawaha River in the Vicinity of the Rodman Basin on
Manatees and Manatee Habitat. Bureau
of Protected Species Management, Florida Department of Environmental
Protection. July 1997.
U.S. Fish and Wildlife
Service. FWS Log No. 96-513C:
Biological Opinion. January 6, 1997.
For additional information contact:
Florida
Defenders of the Environment
4424
NW 13th Street, Suite C-8
Gainesville,
FL 32609-1885
phone: (352) 378-8465
fax: (352) 377-0869
email: fde@fladefenders.org
web: http://www.fladefenders.org
Updated December 2002.