Excerpts from: Fernandez, M., Jr., Goetz, C., and Miller, J. 1984. Evaluation of future base-flow water quality conditions in the Hillsborough River, Florida. United States Geological Survey. Water Resources Investigations Report 83–4182. Tallahassee, Florida.
"The Hillsborough River has been the principal water-supply source for the city of Tampa since 1926. In 1945, part of the lower Hillsborough River in northeast Tampa was impounded by construction of the Tampa Reservoir dam. In 1964, the city of Tampa Water Department began intermittent pumping from nearby Sulphur Springs into the Hillsborough River above the dam to augment supplies when needed."
"The Hillsborough River basin is in west-central Florida (fig. 1). From its source in Pasco County, the river flows 54 miles southwest to Hillsborough Bay. Land-surface altitudes in the basin range from near sea level at the mouth of the Hillsborough River to about 140 feet above sea level east of Plant City (Menke and others, 1961). The Tampa Reservoir dam (fig. 2) is on the Hillsborough River, 10 miles above its mouth, and impounds water from a drainage area of about 650 mi . During base-flow periods, flow of the Hillsborough River is sustained by discharge from Crystal Springs that supplies an average discharge of 59.4 ft /s. Concentrations of various chemical and biological constituents such as nitrogen species, dissolved solids, and coliform bacteria are highest during base-flow periods.
"Tampa Reservoir is long and narrow and extends about 12.5 miles upstream from the dam, meandering through large urban areas of north Tampa and Temple Terrace. The reservoir has a V-shaped channel that averages about 15 feet at the deepest point in any cross section. During low stages, the lower part of the reservoir has one main deep channel and one or two shallow side channels that span a width of about 1,000 feet near the dam. Upstream channel widths may narrow to about 100 feet or less. Bottom sediments range from sand to soft silt and clay with organic detritus rather than a hard packed or scoured bottom (Goetz and others, 1978).
"Above Tampa Reservoir, the Hillsborough River has a V-shaped, meandering channel that ranges in depth from about 1 to 16 feet. At low flow, the channel ranges in width from about 30 to 130 feet. In a 4-mile reach upstream from Flint Creek, the river has many shallow channels and flows through a large swampy area. Small rapids are present above New River; bottom sediments are predominantly sand with limestone and chert boulders in the rapids areas.
"Tributaries to the Hillsborough River that have perennial flow are Big Ditch, Blackwater Creek, and Flint Creek (fig. 2). Nonperennial or intermittent tributaries include Indian Creek, New River, Two Hole Branch, Basset Branch, Hollomans Branch, Clay Gully, and Trout Creek. Cypress Creek, also a nonperennial stream, is tributary to the study reach via a large swamp area. The Tampa Bypass Canal is used to divert flood waters for the Hillsborough River into Hillsborough Bay."
Excerpts from: Munson, A., M. Kelly, J. Morales, and D. Leeper. 2007, Proposed minimum flows and levels for the upper segment of the Hillsborough River, from Crystal Springs to Morris Bridge, and Crystal Springs.Southwest Florida Water Management District, Brooksville, Florida.
"The Hillsborough River begins in the Green Swamp area of Pasco and Polk counties; as do three other major rivers in Florida: the Withlacoochee, Peace and Ocklawaha. The Green Swamp region of central Florida consists of an estimated 870 square miles of low-lying flatlands and swamps flanked by several topographic ridges. In this region of flat topography, seasonal rainfall accumulates over the landscape forming extensive headwater swamps. After leaving the swamps, the Hillsborough River, with an estimated drainage area of 675 square miles as determined from SWFWMD land use maps (or 650 square miles as reported by USGS), flows 54 miles southwesterly into Hillsborough Bay. Annual mean discharge for the Hillsborough River near Tampa for the period 1939 to 2004 was 446 cubic feet per second (cfs). The Hillsborough River watershed (Figure 2-1) extends over parts of three counties, including much of the northeastern quarter of Hillsborough County, a large area of central Pasco County, and a small portion of northwestern Polk County. It is bounded to the north by the Withlacoochee River watershed, to the east by the Peace River watershed, to the south by the Alafia River watershed, and to the west by the North Coastal and Tampa Bay watersheds. It incorporates parts of Tampa, Lakeland, Dade City, Plant City, the community of Land O' Lakes, and all of the municipalities of Zephyrhills and Temple Terrace. The watershed ends at the Tampa Bypass Canal (TBC) basin. The TBC basin is not within the USGS boundaries of the Hillsborough River watershed, but is highly influenced by it (refer to TBC Minimum Flows and Levels Report, SWFWMD 2005)."
