hydraulically connected to the brackish Anclote River to the west through 
a sinkhole in its northwestern end and salinities in the lake fluctuated 
widely. In 1969 a dike was built separating the sink from the lake, 
resulting in a rapid drop in salinity and nutrient levels (Bartos, 
Rochow, and Courser 1977). After removal of the sink, Brooker Creek 
became a more dominant factor influencing the lakes limnology. Brooker 
Creek drains 42 square miles which is characterized by wetlands, citrus 
groves, and numerous lakes. The Lake Tarpon drainage basin including 
Brooker Creek is about 11% urban development with the remainder split 
between wetlands and agriculture. Water quality in the lake is 
relatively good with moderately high nutrient levels, but recent blooms 
of blue green algae have caused concern. As previously mentioned in the 
hydrological discussion, outflow from Lake Tarpon is through the Lake 
Tarpon Outfall Canal which runs south and southeast to Old Tampa Bay. 
Assuming that nutrient concentrations in the outfall canal are similar to 
those in the lake, levels of nitrate, ammonia, and phosphorus are low 
compared to other streams in the region (Table 2). 
To the east of Lake Tarpon lies Double Branch Creek which drains a 
small watershed (19 sq. mi.) at the northern end of the bay. Near its 
mouth the creek is in good physical condition with adjacent tidal marshes 
intact, but high nutrient and bacteria concentrations are found during 
the wet season due to upstream urban and pastureland runoff. 
Perturbations to this creek are much less than for the creeks immediately 
to the east, however, and high color values indicate the influence of 
wetlands in this drainage basin. 
Rocky and Sweetwater Creeks drain northwestern Hillsborough County 
including parts of the City of Tampa and both of these basins have 
experienced rapidly increasing urbanization. Both streams are 
channelized near their mouths and are inter-connected upstream by a flood 
control conduit, "Channel G". Another flood control facility, "Channel 
A", diverges off from Rocky Creek 4.4 miles above its mouth and also 
flows to the bay. Salinity barriers were constructed in Rocky Creek and 
Channel A during 1977-78. Water quality in both Rocky and Sweetwater 
Creeks has been seriously affected by stormwater runoff and municipal 
wastewater discharges, resulting in low dissolved oxygen and high levels 
of coliform bacteria and nutrients, particularly nitrogen species (Table 
2 ). 
South from Sweetwater Creek to the tip of the Interbay Peninsula 
lies the City of Tampa and the remaining drainage to Old Tampa Bay. 
Drainage from this urban area is through underground storm sewers and 
ditches to the bay. One of these drainage systems, the Gandy Boulevard 
Drainage Ditch, was monitored by Lopez and Giovanelli (1984), who found 
that total nitrogen and phosphorus were highest in the baseflow sample, 
but that the majority of nutrients, BOD, and lead were contributed to the 
bay during storm events. 
36 
