13
1000
500
--Near High Springs
200 .. .
z
0
5J
o 0
z
0
20 At Worthington
Oct Nov Dec 1932 1933 Jan Feb Mar Apr
FIGURE 5.-Flow of Santa Fe River upstream and downstream from its underground reach.
During the 7 months covered, flow of the river at Worthington, upstream from the underground reach, ranged from 7 to 1,930 mgd (million gallons a day), or 11 to 2,980 cfs. Near High Springs, downstream, it ranged from 94 to 1,630 mgd, or 146 to 2,520 cfs. Evidently, during low flow and falling stages at high flow this reach of the river gains very substantially from ground water. During rising stages at high flow, it loses moderately to ground water.
the flow of the lower St. Johns may turn out to be even larger when determined.
Most of the major streams-including the Suwannee, St. Johns, Oklawaha, Santa Fe, Hillsborough, and Waccasassa Rivers and the two WithlacoocheaRivers-receive a part of their flow from artesion springs. At high stages, water from the Suwannee River backs into many of the numerous springs along its course. The flows of the Oklawaha and the southern Withlacoochee Rivers are sustained at medium and low stages by Silver Springs and Rainbow Springs, respectively-the State's largest two springs. The operation of a hydroelectric plant on the Withlacoocheiowes its existence to the discharge of Rainbow Springs. The Hillsborough River is the source of supply for Tampa, the third largest city of the State.
Inundating floods of the Suwannee River (see fig. 7) doubtless have helped to retard economic development in the river basin. Optimum design of control structures will require an adequate understanding of the effects of water movement in the limestone formations through which. the river has cut its channel. The flow of