Storm sewer systems that have been put in place during the last 
century were built without benefit of water quality treatment or best 
management practices. Water quality regulations in the state of Florida 
and specifically in the Tampa and Sarasota Bay areas were being developed 
during the period from approximately 1980 to 1982, were formalized 
between 1982 and 1984 and began rigorous implementation from 1984 to the 
present. Because the vast majority (possibly up to 90% or more) of the 
current urban buildout in areas tributary to Tampa and Sarasota Bay 
occurred prior to 1982, it may be assumed that these areas are 
discharging untreated, non-point source pollution. 
In order to better illustrate the effects of urbanization and non¬ 
point source controls on stormwater loadings, the results from two 
wasteload allocation studies performed either by or at the request of the 
Florida Department of Environmental Regulation (FDER) can be presented. 
Non-point source loading was one of the major pollution inputs to the 
wasteload allocation. Estimates of non-point source loadings in both the 
Tampa and Sarasota Bay studies were calculated using the USGS regression 
equations and/or NURP data. 
The analysis for the Tampa Bay system was performed using three 
land use conditions: 1) the entire tributary watershed as 100% forested 
or natural; 2) current land use distributions; and 3) future land use 
distributions. 
Table 2. Ratios of natural and year 2000 land use loadings to current 
(1983) conditions. (From: McClelland, 1984.) 
Loading Ratio* 
Land Use 
Total N 
Total P 
m 5 
Natural (100% forested) 
0.64 
0.29 
0.38 
Year 2000 with no NPS controls 
Year 2000 with urban and 
1.10 
1.05 
1.13 
agricultural BMP’s 
0.99 
0.85 
0.99 
*Numerical average of values for Old Tampa Bay, 
Main Bay. 
Hillsborough 
Bay and 
Using the existing condition as a base, estimates for the 
contribution of "Natural Conditions" ranged from 29% to 64% of the 
current loading for phosphorus, BOD, and nitrogen. In other words, only 
29% to 64% of the current loading of these constituents reached the Tampa 
Bay system under natural conditions. Between 110% to 113% times the 
loading occurs for future conditions with no controls and from 85% to 99% 
occurs for future conditions with controls. 
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