- Stormwater pollution problems have been increasing as urbanization expands. League City, TX, located in the Houston metropolitan area, is a highly developed region which experiences the typical stormwater problems experienced in urban areas. The City plans to construct Low Impact Development practices (LIDs) as an alternative stormwater management approach to negate urbanization problems. To evaluate the effectiveness of LIDs, an analysis of the current pre-development state was performed over the whole Clear Creek watershed as a baseline scenario. This study focuses on calibration, validation, and uncertainty analysis for 8 years from 2004 to 2011 using Soil and Water Assessment Tool (SWAT) and Sequential uncertainty fitting 2 (SUFI2). Streamflow and two constituents (NO2 plus NO3 and TP) were simulated as a monthly and daily basis. All simulated results for the water quantity and quality were in reasonable agreement with the observed values by meeting the standard value of the goodness of fit and the degree of the uncertainty. Several LID designs scenarios at suburban scale are developed and modeled to evaluate the effects of each or combination of LID practices. The results will be analyzed and recommendations for LID policy at development scale will be developed for future use by Coastal zone cities. In this presentation the modeling results will be shared.