Lake Panasoffkee SWIM Plan - Southwest Florida Water ...

submerged and emergent vegetation, the boat ramp and access channel are not navigable
and it is not used by the public or agencies responsible for managing the lake. Tussocks,
floating islands of marsh plants, are another impediment to navigation. Tussocks are formed
when emergent rooted aquatic plants (such as cattails, pickerel weed and arrowhead) break
free and form free floating islands. These plant islands can impede navigation and access
to the shoreline if they accumulate along the shoreline due to wind and wave action.
Pollutant Load Reduction Goal (PLRG): The FDEP requires that a PLRG be developed for
each SWIM water body. A "Pollutant Load Reduction Goal - means estimated numeric
reductions in pollutant loadings needed to preserve or restore designated uses of receiving
bodies of water and maintain water quality consistent with applicable state water quality
standards (Chapter 62-40, Florida Administrative Code)." To develop a PLRG it is first
necessary to develop a goal for the waterbody. With respect to water quality, one method for
setting a pollutant load reduction goal is referencing historicwaterquality and framing the goal
in terms of returning water quality to a more pristine or undisturbed condition. A problem with
this approach is that reliable pre-disturbance water quality data are often lacking. However,
paleolimnological analyses may be used to reconstruct pre-disturbance water quality based
on evaluation of the remains of microscopic flora and fauna (phytoplankton, zooplankton and
benthic macroinvertebrates) found in sediment cores.
Paleolimnological analysis was performed based on diatom identifications and Trophic State
Index (TSI) reconstruction techniques. Based on analysis of sediment cores, it was concluded
that very few changes have taken place in and around the lake since 1855 (Belanger 1993).
In fact, analysis suggests that the trophic state of the lake was once eutrophic during this
period and had moved toward a more mesotrophic state since about 1970.
Trophic state, a measure of the degree of nutrient enrichment, is frequently used to classify
lakes. A TSI can be calculated on the basis of chlorophyll a concentration, Secchi disk
transparency, or limiting nutrient concentrations. Trophic state evaluations of Lake
Panasoffkee indicate that the lake is nutrient balanced, meaning the lake will respond to
increases in either nitrogen or phosphorus.
Water quality data collected by CH2MHill (1995) indicates that the TSI for the lake is 47,
which places it in a mesotrophic category. This value is essentially the same as that
calculated by Bays and Crisman (1981), 46, and from the USGS data taken from 1977 to
1990, 45.
Paleolimnological research, the fact that Lake Panasofkee currently meets Class 111 Water
Quality Standards and the apparently steady TSI value support a proposed PLRG of "zero"
for nutrients. A PLRG of "zero" indicates no apparent need for corrective measures to
decrease nutrient loading to the system. It should be noted that a PLRG is an overall system
target and does not preclude the implementation of management strategies to maintain
existing water quality. On the contrary, where opportunities exist to enhance or protect
existing water quality they should be implemented.