Generalized least squares (GLS) techniques were used with at-site statistics, from PeakFQ, and drainage area for streamgages in Puerto Rico to calculate regional regression equations for ungaged locations. The GLS approach assigns weights based on uncertainty of the observations (ie. record length and variance) and accounts for correlated streamflows and time-sampling errors (Farmer and others, 2019). Two separate regions were defined for the use of these equations to minimize residuals, and performance metrics from WREG were analyzed to determine drainage area as the only explanatory variable provided the best results. Values for the correlation smoothing function in region 1 were alpha equal to 0.006 and theta of 0.96 and for region 2 alpha equal to 0.004 and theta of 0.94. This data release includes (1) a PeakFQ folder that contains input files, both .EXP and .PRT (output from PeakFQ), for use in WREG; (2) a SiteInfo folder for use in WREG that contains information about each site used, separated by region; and (3) a Results folder showing the WREG output of each annual exceedance probability flow, separated by regression region where applicable. References Cited: Farmer, W.H., Kiang, J.E., Feaster, T.D., and Eng, K., 2019, Regionalization of surface-water statistics using multiple linear regression: U.S. Geological Survey Techniques and Methods, book 4, chap. A12, 40 p., Accessed August 4, 2020 at https://doi.org/10.3133/tm4A12.