FLOOD CONTROL CHANNELS 
Tampa Bay receives freshwater flow from a number of flood control 
channels. These are manmade canals which diverge from natural waterways 
and are primarily used during intermittent high flow periods. Flows in 
these canals are controlled by gates which are operated in response to 
hydrologic conditions. Channel A, which diverts water from Rocky Creek, 
originates in northwest Hillsborough County and drains to Old Tampa Bay. 
The Lake Tarpon Outfall Canal, which was built in Pinellas County 1971, 
drains the Lake Tarpon watershed and also empties into Old Tampa Bay. 
Flows in this canal, which average 34 cfs, are manipulated to facilitate 
water level fluctuations in Lake Tarpon and to provide storage in the 
lake for the summer rainy season. 
By far the largest flood control structure in the region is the 
Tampa Bypass Canal which was constructed between 1974 and 1983. This 19 
mile structure which lies east of Tampa is used to divert high flows from 
the Hillsborough River and prevent flooding in the cities of Tampa and 
Temple Terrace. The canal originates nearer the Hillsborough River 
northeast of Tampa and empties into McKay Bay, an arm of Hillsborough 
Bay, through the channel of the old Palm River. The lower portions of 
the canal receive flow from groundwater seepage and stormwater runoff, 
although very high flows in the canal are restricted to diversions from 
the Hillsborough River. This operating schedule creates hydrographs 
which are characterized by long periods of relatively stable flows 
followed by abrupt discharge peaks during periodic wet periods, such as 
that accompanying Hurricane Elena in 1985 (Figure 10). 
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