SCCF ConServation noteS
In the 1930s, the Herbert Hoover Dike was constructed around the lake following the disastrous hurricanes of 1926 and 1928. The Caloosahatchee canal was dredged to a depth of eight feet. In an effort to expand the capacity of the outlets for the lake to the east (to the St. Lucie River) and west in the 1950s and ‘60s, the Caloosahatchee was dredged to 25 feet, straightened and widened to a quarter mile.
of 2005, a bloom of toxic blue-green algae (microcystis) covered the Caloosahatchee and St. Lucie rivers. So little was known about the health affects of this algae that people on both the east and west coasts queried several agencies before finding out from the World Health Organization that
the algae was toxic. Blooms continued through 2007.
Red tide and
In addition, three lock-and-dam structures were added to the Caloosahatchee to control the flow of the water and prevent saltwater intrusion upstream of the Franklin Lock (S-79). In the 1960s the Kissimmee River, which flowed into Lake Okeechobee from the north, was channelized and transformed into a 30-foot deep, 50-mile shortcut. Water that had originally meandered south through a miles-wide floodplain now ran in a straight shot to the lake, carrying the agricultural runoff from the Kissimmee basin with it.
The result of these construction projects was that the amount of water flowing into Lake Okeechobee was greatly increased and the storage areas and outlets for the water were decreased. In addition, the Herbert Hoover Dike is an earthen berm, not an engineered dam. After Hurricane Katrina breached the New Orleans levees, concerns about the safety of the dike around Lake O intensified and dike repairs are currently underway.
The rain-heavy hurricane seasons of 2004 and 2005 stressed the system to emergency conditions. At one point lake levels rose six feet in six weeks. Winds whipped the lake, churning 50 years of polluted sediments from the lake bottom into the water column. Concerns about the safety of the dike caused water managers to dump water from the lake quickly -- by the billions of gallons -- into the Caloosahatchee and St. Lucie rivers.
microcystis blooms were followed by increasing lyngbya in the bay, coastal blooms of trichodesmium and the red drift algae that piled up on the beaches of Sanibel. In 2006, the Caloosahatchee was named the seventh most endangered river in the nation by American Rivers, and SCCF began raising money to purchase six sensors to monitor water quality. Support for RECON was so strong that eight sensors were purchased. Seven are deployed at fixed locations; the eighth will be deployed on a mobile basis to monitor events of interest.
If you want to learn more about the history of the Caloosahatchee, SCCF is launching a new series, “First Mondays: Policy at SCCF,” a series of monthly presentations by Rae Ann Wessel in the Nature Center auditorium. Topics will include a wide range of issues affecting southwest Florida and our coastal islands. On June 2, Rae Ann will talk about “How the Greater Everglades Ecosystem Affects Sanibel & Captiva.” Each month there will be a recap of the meetings and issues of the previous month as well as a preview of the upcoming month; there will be time for Q&A following the presentation. The public is invited; reservations are not required. For more information, call SCCF at 472- 2329. This column was excerpted from a presentation given by Rae Ann at the Everglades Coalition Conference, held at South Seas Resort in January 2008.
When both rivers turned the color and consistency of green paint it was clear the system was broken. In the summer
This column ran in the Island Reporter (www.island-reporter.com) on May 22, 2008
SCCF is dedicated to preserving natural resources and wildlife habitat on and around Sanibel and Captiva islands through
Marine Research • Natural Resource Policy • Land Acquisition
Native Plant Nursery & Landscaping for
Sea Turtle Conservation • Environmental Education
ildlife Habitat Management & Research
3333 Sanibel-Captiva Road (P.O. Box 839), Sanibel, FL 33957 Telephone: (239) 472-2329 Real-time RECON Water Quality Data at www.recon.sccf.org www.sccf.org
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