The Tampa Bypass Canal is part of a flood-control project east of the city of Tampa under construction by the U.S. Army Corps of Engineers. It will divert floodwater from the Hillsborough River at points upstream from Tampa through a canal system to McKay Bay. The U.S. Geological Survey began a hydrologic data program in 1974 to provide data needed to identify existing hydrologic conditions and to evaluate the effects of canal construction. A network of surface-water and ground-water sites was designed to monitor changes in nutrients, trace metals, major inorganic constituents, pesticides, and benthic invertebrates along the canal system; to monitor changes in trace elements, common constituents, nitrates, specific conductance, and chlorides in the Floridan aquifer; and to monitor changes in the potentiometric surface of the Floridan aquifer.

In 1974-75, the monitoring program consisted of drilling 12 monitor wells and initiation of the surface-water sampling program. In 1976, the program consisted of drilling five additional wells, continuation of the surface-water sampling, initiation of ground-water sampling program, and monitoring of discharge from springs.

Water-quality data for nine surface-water sites in the basin were collected at each of the control structure sites, in the tidal portion of the canal, and at each of the major tributaries to the canal system.

Fifteen ground-water sites were sampled annually to provide information on ground-water quality. Ten wells were sampled semiannually for dissolved chloride concentrations to provide information on the freshwater-saltwater interface. Ground-water levels were collected at 34 wells in the areas adjacent to the canal to monitor changes in the potentiometric surface in the Floridan aquifer.

Discharge measurements from springs along the canal system were made in 1969-73 and 1976 to provide data on the quantity of ground water entering the canal. A daily discharge station was operated at structure S-160 to determine quantity of water flowing from the canal system into the bay.