REPORT OF INVESTIGATIONS No. 42


budget the combined basins east of State Highway 33 are referred
to as eastern basins.
 Runoff of the Little Withlacoochee River at Rerdell (station
43) is representative of the natural drainage in the western part
of the Green Swamp area. Streamflow at the gaging station is
derived from rainfall on the Little Withlacoochee River basin. The
drainage area at station 43 is 160 square miles.
 Water budget analyses were made for the eastern and western
basins. Figure 52 shows the daily streamflow from these basins
for the calendar years 1959-61. Streamflows, ground-water levels,
and lake levels were nearly the same at the beginning and end of
the year both in 1959 and 1960. Although these were the 2 wettest
years of at least 60 years of record in central Florida, the indicated
year-end storage changes were small and insignificant.
 The year 1961 was one of the driest of record, and the annual
runoff was low. Stream discharges were less and water levels, as
indicated at representative ground-water observation wells and
lake gages, were generally 1 to 3 feet lower at the end of 1961 than
at the beginning. The surface runoff from the eastern basins in
1961 was 1.7 inches and that from the Little Withlacoochee River
basin was 0.8 inch.
 Ground-water outflow from the Floridan aquifer in the eastern
and western basins was computed using the piezometric maps
(figs. 35 and 36). The piezometric surfaces shown by the map
for November 1959 (fig. 35) and the map for May 1962 (fig. 36)
represent the flow conditions and the probable range in the rates
of ground-water movement during wet and dry periods, respec-
tively. The piezometric surface representing flow conditions for
the year 1961 was assumed to be the average between that
shown by maps for November 1959 and May 1962.
 The western part of the Green Swamp area, as represented by
 the Little Withlacoochee River Basin received more rainfall each
 of the 3 years than did the eastern part of the area. Runoff from
 the eastern basins was almost as much as that from the Little
 Withlacoochee River basin in 1959 and 1960 even though the
 rainfall was 3.4 inches less in 1959 and 5.6 inches less in 1960. In
 1961, a dry year, 0.9 inch more runoff occurred from the eastern
 basins than that from the Little Withlacoochee River basin
 although the yearly rainfall was 0.9 inch less.
 Where and when the ground-water and surface-water divides
 coincide, some ground water from the nonartesian aquifer
 discharges from a basin as the base flow of the stream draining


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