STORMWATER INPUTS TO TAMPA AND SARASOTA BAYS 
Ronald F. Giovannelli 
Florida Land Design & Engineering, Inc. 
Tampa, Florida 
INTRODUCTION 
This paper presents information regarding stormwater inputs to 
Tampa and Sarasota Bays. Discussions will center primarily on the urban 
rather than agricultural aspects of stormwater. Information will 
supplement previous data on overall watershed characteristics and stream 
or river flows to Tampa and Sarasota Bays. Unique rainfall 
characteristics for the Tampa Bay area as they relate to runoff quantity 
and quality will be discussed, as well as urbanization patterns and 
changes in land use which cause natural stream flow to be characterized 
as urban runoff. Runoff volumes are compared for the Tampa and Sarasota 
Bay systems to other Gulf coast areas. In addition, loadings for 
selected constituents are presented for various land use and treatment 
scenarios. 
PHYSICAL SETTING 
The watersheds tributary to Tampa and Sarasota Bays are shown in 
Figures 1 and 2, respectively. For the Tampa Bay system the surface 
water area of Tampa Bay is approximately 400 square miles, while the area 
of tributary watershed is approximately 1800 square miles, a ratio of 4.5 
to 1, watershed to bay surface area (Treat, 1982). In the Sarasota Bay 
system the water surface area is approximately 40 square miles and the 
tributary area is approximately 30 square miles excluding the Phillippi 
Creek watershed, which is approximately 50 square miles, a ratio of 0.75 
(or 2 to 1, depending upon whether Phillippi Creek is included). 
PREVIOUS RESEARCH 
A significant amount of data has been collected on urban runoff in 
selected tributaries to Tampa Bay. Prior to 1975, information was 
primarily quantity-based and resulted from studies on flooding. From 
1975 to 1983, however, two major projects were conducted which resulted 
in significant research on rainfall, runoff quantity, and runoff quality. 
The first of these two studies was a cooperative program instituted by 
the U.S. Geological Survey (USGS) and five local governments between 1975 
and 1979. In this study, nine urban gauging stations were installed in 
mixed land use basins ranging from approximately 0.3 to 3.0 square miles. 
Both runoff quantity and quality were collected through the duration of 
the study and published in two separate USGS reports, one quantity based 
(Lopez, 1983) and one quality based (Lopez, 1984). 
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