in its entirety would be expected to meet the targets. The 
modeling showed that the low flow and high flow simulations 
with no point sources were considerably different and that 
little is gained during the low flow season with the 
imposition of BMP’s [best management practices]. However, 
a significant improvement in the chlorophyll a 
concentration was predicted for Hillsborough Bay when 
agricultural and urban BMP’s were considered for the year 
2000 non-point source loadings. These simulations also 
included a limited nutrient discharge of the Alafia 
phosphate mines. It is recommended that in the 
Hillsborough Bay drainage basin, urban and agricultural 
BMP’s be implemented in order to reduce the nutrient load 
in Hillsborough Bay. For Old Tampa Bay, due to the nature 
and size of the watershed, only small improvements are 
predicted with the imposition of BMP’s. The non-point 
source simulations also indicate that the benthic fluxes of 
oxygen demand and of nutrients make a considerable 
difference in the condition of the bay. In particular, 
reduction of the fluxes to the low flow values for the high 
flow simulations resulted in a significant improvement in 
the bay. 
The DER report’s conclusion that BMP’s may not significantly 
improve the bay speaks to the enormity of stormwater impact, if the 
report is a valid assessment. If it is not, much more evaluation will be 
needed. As the DER report acknowledged, point source impacts were not 
incorporated in the 1988 water quality assessment. Details of industrial 
discharges and major water quality impacts to the bay are given in 
Phillips et al., elsewhere in this report. 
WATER QUALITY ISSUES IN BAY MANAGEMENT 
Since 1972, state law requires domestic waste water disposal 
facilities discharging into tidal waters of west-central Florida 
(including Tampa and Sarasota Bays) to provide advanced waste water 
treatment (AWT). A modified version of the law is in effect today, 
although a period between 1980-81 and 1987 passed in which AWT 
requirements were relaxed and the Florida Department of Environmental 
Regulation was instructed to specify water-quality based effluent 
limitations (WQBEL) on a case by case basis. The WQBEL approach operates 
on the principle that a receiving water can only accept a certain load, 
irrespective of source, and that decisions are needed to allocate 
increments of waste load to specific sources. 
Such waste load allocations could also be based on best available 
technology or impacts to living resources. In any case, some method is 
needed to analyze the combined effects of existing or proposed loads and 
the DER has used a numerical model of circulation and water quality for 
that purpose (although their original intent to base specific waste load 
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