FLORIDA GEOLOGICAL SURVEY


records on the basis of 27 years of records for Escambia River near Cen-
tury. The flow-duration curve given in figure 8 was also adjusted on the
basis of this long-term station.
 Boggy Creek drains an area of 27 square miles. Based on unit runoff
per square mile of nearby streams, the average flow of Boggy Creek is
estimated to be 50 cfs.
 McDavid Creek drains 34 square miles in Escambia County and
flows into the Perdido River a mile above Barrineau Park. The average
unit runoff from this basin is estimated, on the basis of discharge meas-
urements and correlation with records of nearby basins, to be 1.9 cfs per
square mile, giving a total flow from the basin of 65 cfs.
 Jacks Branch, a tributary entering the Perdido River west of Canton-
ment, has the lowest runoff of any stream gaged in the Perdido River
basin. The average unit runoff was computed to be 1.0 cfs per square
mile. The Jacks Branch basin covers 24 square miles and produces an
average flow of 24 cfs. The minimum daily flow measured at the gaging
station is 3.0 cfs, or 0.13 cfs per square mile. The flow-duration curve
given in figure 17 has a greater slope than that for other streams in the
area and shows the flow of Jacks Branch to be more variable.
 The low yield of Jacks Branch, as compared with other streams in the
 area, is a result of unusually low base flow or seepage to the stream.
 Only about 30 percent of the total runoff is base flow, whereas the base
 flows of other streams comprise from 55 to 75 percent of the total. Direct
 surface flow, or overland flow, of Jacks Branch is about the same as other
 streams, based on a unit area comparison. The average annual runoff of
 Jacks Branch is 14 inches.
 Elevenmile Creek drains into the north end of Perdido Bay and is
 used for industrial waste disposal.
 Bayou Marcus Creek drains 25.9 square miles along the northwestern
 outskirts of Pensacola and empties into the northeast corner of Perdido
 Bay. Two years of records were collected at a gaging station located at
 U.S. Highway 90 prior to construction of a dam in February 1960. The
 dam created a reservoir of about 60 acres above State Road 296, about
 two miles upstream from the gaging station.
 An average annual flow of 43 cfs was measured at the gaging station
 from a drainage area of 11.2 square miles. This unit runoff of 3.8 cfs per
 square mile is the highest unit runoff within the two counties. The aver-
 age runoff from this small area is about 50 inches per year, or 80 percent
 of the average annual rainfall. This high runoff is probably derived from
 large rates of ground-water inflow from areas outside the surface drain-
 age divide.