Thousands of Carolina bays are found on the Atlantic Coastal Plain bet
ween northern Florida and New Jersey. Most of these shallow depression
s are wetlands, and many hold temporary ponds that fluctuate in respon
se to seasonal or long-term climatic conditions. Despite the abundance
of bays, few studies have described their hydrologic regime. This stu
dy examines the hydrologic interactions of Thunder Bay, a 7-ha Carolin
a bay located on the Upper Coastal Plain of western South Carolina. Da
ta from 38 piezometers, borehole logs, and records of pond stage and w
eather indicate that water ponded at Thunder Bay is a surface expressi
on of the water table. Although fluctuation of pond stage is largely c
ontrolled by precipitation and evapotranspiration, nearly continuous s
eepage losses coupled with periodic ground-water inflow are also impor
tant components of Thunder Bay's hydrologic regime.