11 Map showing results of low-flow investigation of Withlacoochee
 River, May 23-25, 1961 -...-.- ..- ... --..-.--- .... ----.--------- In pocket
12 Graphs showing annual and mean monthly discharge of With-
 lacoochee River at Trilby ._-.. -_.-____ ...-..-...... ...--------. ---------- 40
13 Relation of mineral content to discharge at gaging stations in
 Withlacoochee River basin ..--..- ----..-..-....-------------------- 42
14 Flow diagram of the upper Oklawaha River ___--------.__.------------. 45
15 Flow-duration curve for Big Creek near Clermont, 1931-62 .--..-..-----. 50
16 Relation of mineral content to discharge at gaging stations in
 upper Palatlakaha Creek basin .........---...............------- -------------.......51
17 Relation of mineral content to discharge, Hillsborough River
 near Zephyrhills ---..---.._. ............--- -- --------.-----------------------. 53
 18 Relation of mineral content to discharge, Horse Creek at Davenport 54
 19 Double-mass curves of measured runoff versus computed run-
 off, Withlacoochee River and Palatlakaha Creek basins .--.------- --60
 20 Graphs of monthly rainfall and runoff for July 1960 to June
 1962 and estimated base flows for November 1960 to June 1962,
 Horse Creek at Davenport _____ ... --. ......-- ...-..-----.. --------------- 62
 21 Graphs of monthly rainfall and runoff for uly 1960 to June 1962
 and estimated base flows for November 1960 to June 1962,
 Pony Creek near Polk City .-...---.-.---....----...----.---- ---------- 63
 22 Flow-duration curves for Horse Creek at Davenport and Pony
 Creek near Polk City, 1960-62 ------..........---......------.....---...---....-.----. 66
 23 Hydrographs of long-term records of ground-water levels near
 the Green Swamp area --...-----.................-------....------....--- In pocket
 24 Hydrographs of water levels and rainfall at wells in the Green
 Swamp' area, 1959 --...----. ---..-.....-------------..... --..-.....--- .------- 71
 25 Hydrographs of water levels in wells (805-155-1, 2, and 3)
 near Lakeland .............__.--------------------........-------.. --- In pocket
 26 Hydrographs of water levels in wells (808-155-1, 2) 4 miles
 north of Lakeland and in a well (815-157-2) 12 miles north
 of Lakeland _-...---..... .....------ --___ ...---........------ --------- 72
 27 Hydrographs of water levels in wells (810-144-1, 2; 813-149-1,
 2; 813-150-2; 814-143-1, 2; 815-149-3) in south-central Green
 Swamp and in wells (815-134-1, 2; 815-139-2, 3) about 9 miles
 north of Haines City ..............----..----..... _.. ....-----..... .....-----.. 73
 28 Hydrographs of water levels in wells (821-202-3; 822-149-1, 2;
 832-154-1, 2) in north-central Green Swamp; in a well (826-
 211-1) 5 miles north of Dade City; in wells (822-138-1, 2) 17
 miles north of Haines City; and in a well (833-137-2) 7 miles
 east of Clermont ..------. --____. -----__.. __ ___ --___ -__--- ... 74
 29 Hydrographs of water levels in wells 810-144-1, 2 and of Lake
 Lowery and Lake Mattie .......----....-.....- ---------.... .. ..__ .. ... 75
 30 Graphical determination of specific yield --_ ---_.-..---- 77
 31 Map of Green Swamp area showing depths to the top of the
 Floridan aquifer .------ ..--.... .----- --------.--..-....... In pocket
 32 Map of Green Swamp area showing the limestone formations
 that comprise the top of the Floridan aquifer and contours on
 its upper surface .----- ----------------------................. In pocket
 33 Map of Florida showing contours on the piezometric surface of
 the Floridan aquifer, 1961 ---...................-----------------...... .. In pocket