Conclusion of Recent University of South Florida Water Quality Study around Mashes Sands 

Attached are the conclusions reached in a recent University of South Florida Water Quality study around Mashes Sands.  I have the complete study I can send, but it is 82 pages long and a large file, so send me an e-mail if you want the whole report.

Ron Piasecki
ron_piasecki@earthlink.net

V. Conclusions

The data collected during this study strongly indicate that human fecal pollution affects water quality in some of the coastal and estuarine sites sampled in Wakulla County, particularly those near the mouth of the Ochlocknee River.  Even though regulatory standards for fecal coliforms and enterococci were infrequently exceeded, human-associated MST markers were detected regularly in the area of study.

{sidebar id=1}Potential point sources of pollution were noted at the Mashes Sands Beach, the nearby boat ramp, and the Ochlocknee River. Mashes Sands Beach used to be serviced by a bathroom (formerly on septic system) that has been connected to the nearby lift station.  The former septic system should be removed from the site.  The storm surge during the 2005 hurricane season demolished the structure, and today portable restrooms are present instead.  Results obtained in the previous study conducted in the Hillsborough County (unpublished data) have shown that cleaning practices  employed at the portable restrooms can result in increased concentrations of indicator organisms and human-associated markers in nearby water bodies, into which the water has drained.  High frequencies of human-associated MST markers at this site (as well as supplemental sites in the surrounding area) strongly suggest human fecal pollution (Figure 27).

Restrooms located at the nearby boat ramp are connected to the central sewer system, but the high frequency of detection of the human-associated MST markers at the site, as well as several exceedance of the regulatory standards for fecal coliforms and enterococci suggests that they either may not be functioning properly, or that boaters are discharging marine toilets at the boat ramp (Figure 27).  Dye tests are suggested in order to determine whether restrooms are a pollution source at this particular site.  The Ochlocknee River in the vicinity of the Route 319 Bridge is surrounded by housing serviced by septic tanks, as well as several live-aboard boats docked of the shore.  Relatively high frequency of the human-associated MST markers was detected for the duration of the study (Figure 25), suggesting human fecal pollution as a source of contamination.  A series with of dye tests, along with investigation into boat waste disposal practices is suggested.  The possibility of the bacterial deposits upstream from the sampling sites (i.e., household wastes, stormwater run-off, waste disposal practices of recreational boaters, etc.) has not been evaluated in this particular study, and as such it can not be ruled out as a contributing factor.

Both human-associated MST markers used in this study were detected at Alligator Point Beach suggesting human fecal pollution (Figure 26).  Since this site was sampled only two times (Table 1), more data is needed in order to make inference about the pollution source.

Panacea, Shell Point Beach, and Live Oak Island are located north and west from Mashes Sands Beach.  For the duration of the study, there were no exceedances in indicator organism concentrations, and only one positive human-associated MST marker, therefore there appears to be low  probability of human fecal pollution impacting water quality at these sites.  However, due to the relatively low sampling frequency (n=4), more data is needed to rule out the possibility of human fecal pollution.

Previous studies established that stormwater can contribute high levels of indicator bacteria to the receiving waters.  The impact of the stormwater to the receiving waters in the Wakulla County could not be estimated due to the lack of the stormwater infrastructure in the areas sampled.  However, statistical analysis conducted on the data did suggest significant correlation between fecal coliform and E. coli concentrations and the rainfall three and seven days prior to sampling.  In order to investigate stormwater as a possible point source of pollution, sampling during rainy season (summer) versus dry season (winter) is suggested.

The drifter experiment provided interesting results with the respect to the possible bacterial deposition at the Mashes Sands Beach.  In general, drifters were tidally driven, following the depth contours of the bay. Upon the exit from the Ochlocknee Bay, the path followed was over the shoals at the south end of the Mashes Sands Beach and in general eastward direction.  This finding suggests that during the high tide partial outflow from the
Ochlocknee Bay flows onto the beach, possibly depositing bacteria.  Coincidentally, it was found that ending points for drifters have considerably high number of positives for human-associated MST markers (Figure 28), suggesting that hydrology of the region may have an impact on the bacterial transport and deposition.

Data collected in the study indicate that human fecal pollution is impacting recreational water quality in Wakulla County.  At this time, the pollution source appears to be local to the Mashes Sands Beach and Ochlocknee Bay area, since there was not enough data to indicate human fecal pollution further east from this region.  Furthermore, stormwater runoff and local topography and hydrological conditions existing in the Ochlocknee Bay appear to be important contributors to the bacterial loads in these waters.

This letter originally published on November 19, 2007.

Written by :

mkwestmark

 

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