ONE OF THESE CANALS IS NOT LIKE THE OTHERS: Unique Chemistry for a Lake Istokpoga Residential Canal
Erin M. McCarta and Clell Ford Highlands County Natural Resources Sebring, FL
Lake Istokpoga is the fifth largest lake in Florida, at an impressive 27,692 acres, and is considered the crown jewel of Highlands County. From April 2005 to February 2006, the South Florida Water Management District tasked Highlands County with conducting a year long intensive water quality investigation on Lake Istokpoga, for which a private contractor was chosen to complete the sampling and analysis.
The results of this study highlighted a few areas of concern as well as some unusual and unique outliers. A residential canal near the south end of the lake, the Rutledge Canal, has provided the most interesting data. The water in this particular canal has characteristics that are considerably different from all the other 41 sample sites, as well as from the other eight residential canal sites. Found at this site was the highest concentration of Total Phosphorus, the lowest concentrations of Sulfate, Magnesium, and Calcium, and field parameters that measured far outside what other similar sites were producing.
Figure 1: Lake Istokpoga - pH Value Comparison across one year for all residential canal sites
2 Sebring Estates Canal 11 Istokpoga Shores North Canal 33 Bald Cypress Canal
3 Mallard MHP Canal 12 Istokpoga Shores South Canal 35 Elliott Canal West
4 Palms Estates Canal 28 Rutledge Canal 36 Elliott Canal East
A comparison of pH values for all residential canal sites shows the Rutledge Canal site having values substantially lower than the others (Figure 1). The Rutledge Canal site also exhibits similar comparisons for the parameters of magnesium, calcium and sulfate. Another field parameter shown considerably lower at the Rutledge site compared to similar sites is specific conductivity.
Alternatively, total phosphorus concentrations at the Rutledge site is the parameter which is most times shown at levels higher than the average of all residential canals (Figure 2). Four of the nine residential canal sites, one in each quadrant of the lake, were chosen for this comparison. Total Phosphorus is a nutrient which is highly scrutinized in Lake Istokpoga due to its large contributions to waterbodies downstream, including Lake Okeechobee. Although the
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