Geostatistical analysis of closely spaced borehole flowmeter measurements was used to estimate the variance (2.53) and vertical and horizontal correlation lengths of ln K (0.57 and 7.3 m) in the Biscayne Aquifer, a limestone aquifer critical for Florida's water supply and for Everglades restoration efforts. The variance and correlation lengths of the Biscayne Aquifer are similar to some of the values for unconsolidated siliciclastic sediments (especially those at Columbus, Mississippi). The larger &lgr;h for the Biscayne Aquifer (7.3 m) is thought to be due at least in part to the lower lateral variability of the carbonate platform depositional environment, compared to the fluvial environments in which the siliciclastic sediments were deposited. An improved down hole packer would allow for data with finer vertical resolution; the current system is adequate for work inside well screens but cannot adequately seal many spots in open, irregular rock boreholes. Research in rock presents additional logistical difficulties but is important for addressing fundamental questions about solute transport in a wider range of geological media, beyond unconsolidated siliciclastic deposits. ¿ 2001 American Geophysical Union