This study evaluated effects of current landscape configuration (arrangement) on streamflow within a 162.0mi2 (419.6km2) watershed of the Yellow River (Hydrologic Unit Code 10, HUC-10) of the Atlanta, Georgia metropolitan region located within the Southeastern United States (U.S.). Monthly and daily Thornthwaite Water Balance models using landscape configuration (contagion-adjusted curve numbers, CON-adjusted CNs) derived from the most current (2011) land cover/land use (LC/LU) dataset out-performed original CN watershed simulations over the 5-year (60-month and 1826-day) period from January 2009 to December 2013. This was based upon evaluation from several statistically-based, hydrologic model performance predictors. At the reclassified level (urban; forest; and agricultural), configurational metrics related to CON known as the aggregation index (AI) and clumpiness index (CI) indicated greater landscape heterogeneity that may lead to complex flow patterns difficult to simulate within a HUC-10 streamflow model. On the other hand, these related metrics also indicated higher levels of clumping within these reclassified LC/LUs may allow for improved accuracy in simulating streamflow-generating processes across landscapes within a HUC-10 streamflow model. Results also inferred that localized landscape configuration within the largest sub-watershed (HUC-12) of a HUC-10 watershed could have a disproportionate impact on runoff and should be prioritized within regional U.S. watershed management plans.