This report focuses on the hydrologie modeling of the Rio Conchos basin, a main Mexican tributary of the Binational Rio Grande basin. Located in the Mexican State of Chihuahua, the Rio Conchos basin provides about 55% of the water deliveries to the US under the 1944 water sharing treaty between Mexico and the US. However, during drought periods, for instance in 1990s, water deficit under the 1944 treaty can occur. In order to answer several pressing questions related to water availability under future climatic conditions, a hydrologie simulation model has been developed for the Rio Conchos basin using the Water Evaluation and Planning (WEAP) modeling software. This report provides a description of the hydrological modeling of the Rio Conchos basin using the soil moisture method incorporated in WEAP. The Rio Conchos hydrologic model reported here is an extension of the model previously reported in Amatto et al. (2006). In this research, the calibration period for the model has been extended from a one-year period (1980) to a ten-year period (1980-1989) with appropriate adjustments to the model parameters. In addition, a ten-year validation period (1990-1999) has also been added.