This project determined that 70 percent of the river bed is dominated by healthy submerged aquatic vegetation.
Mapping of submerged aquatic vegetation in the Rainbow River began shortly after the Southwest Florida Water Management District (District) designated the river a Surface Water Improvement and Management priority water body in 1989. While the upper half of the river has stable vegetation dominated by strap-leaf Sagittaria, the early results of this project determined that the lower half of the river’s vegetation has been altered by the presence of hydrilla and Lyngbya. These exotic, nuisance species have had a negative effect on the ecological health of the system.
Ongoing mapping efforts provide a detailed evaluation of the bottom habitats, or benthic zone, in select areas of the lower river which have less desirable submerged aquatic vegetation than the middle and upper river. The District continues to monitor the ecological conditions of the Rainbow River including the vegetation and algal communities, along with spring vents, hardened shorelines and emergent vegetation in the river. This data is used to develop a baseline of vegetation and algal coverage and to evaluate the success of management strategies to help stop the spread of undesirable vegetation. The District is planning to shorten the current mapping interval from every four or five years to every two or three years, so that smaller scale changes to the health of the river can be documented and appropriately managed.
The Rainbow River was first mapped in 1991, with subsequent mapping occurring in 1996, 2000, 2005 and 2011. The next mapping effort is planned for 2015.