c.f.s 
rivers (Hillsborough, Alafia) are more urbanized than the southern ones, 
which still contain 90% of their watersheds in wetlands, forest, range, 
and farmland. The Little Manatee watershed is the least urbanized of the 
four rivers and it is generally considered to be the river in the best 
ecological condition. 
Average streamflow rates for these four rivers are presented in 
Figure 7, along with flows for four gauged minor tributaries. Average 
streamflow for the four major rivers correspond to their respective 
drainage basin areas with the Hillsborough having the greatest flow 
followed by the Alafia, Manatee, and the Little Manatee Rivers. Lewis 
and Estevez (1988) estimated that these four rivers contribute 
approximately 85 percent of the total flow to the bay, while Hutchinson 
(1983) indicated this value was near 78 percent. The two largest rivers, 
the Hillsborough and the Alafia, empty into Hillsborough Bay, the 
northeastern division of Tampa Bay. It has been estimated that 
Hillsborough Bay receives 63 to 77 percent of the total freshwater inflow 
to Tampa Bay (Goodwin 1987; Lewis and Estevez 1988). 
Tampa Bay Major Tributaries 
Average Yearly Streamflow and Withdrawals 
mi Streamflow L‘ 1 Withdrawals 
After Withdrawals 
Figure 7. Average yearly streamflow and withdrawals from eight 
tributaries to Tampa Bay. 
27 
