Event rainfall depth, runoff depth, and periodic cover density measurements were taken for a total of 21 plots (2mx2m) at 5 different locations on the National Science Foundation Jornada Long-Term Ecological Research Site in southern New Mexico. Runoff properties are characterized by plot, plot group, and site using Curve Number (CN) analysis. Results show differences within groups, between groups and with cover. Distinct trends of CN with cover are seen with the effects being most profound at the better sites (lower CN). However, a near-common value (CN~90) is projected for all brush sites under conditions of no cover. These findings affirm customary but seldom-demonstrated expectations, and indicate that the most hydrologic improvement per unit of cover would be on the better sites (lower CN), and the futility of vegetation management for hydrologic benefits on the harsher sites (high CN).