Repetitive flooding has devastating consequences on human lives and property annually in cities. The Brays Bayou watershed is one of the most repetitively flooded urban watersheds in the US. Project Brays, a two-decade-long, $480 million regional flood mitigation project, sought to alleviate flooding in Brays Bayou watershed with channel widening as one of its main components. Though the watershed has been studied extensively for its vulnerability to flooding, no study has ever evaluated the effects of Project Brays’ channel modifications with actual channel design configurations. Meanwhile, while there has been some general estimation of Project Brays’ effects, none focuses on Meyerland, one of the most flood-prone neighborhoods inside the Brays Bayou watershed. To fill this knowledge gap, this study evaluates the effects of Project Brays’ channel widening focusing on Meyerland via modeling with actual channel configurations. This study first combines Harris County’s HEC-HMS and HEC-RAS models of the Brays Bayou watershed and incorporates the new Project Brays channel configurations. This approach makes it possible to compare the change in the flood depth, extent of flooded area and number of houses flooded before and after channel widening for a variety of design storms. We found that the channel widening has alleviated flooding upstream of I-610 but has created additional flooding in some areas downstream of I-610 due to the increased conveyance for all four design storms tested. Driven by this unexpected result, we propose a detention opportunity, in which two golf course properties immediately upstream of Meyerland are converted to detention basins to reduce flooding. Our modeling shows that detention has better flood mitigation effects than Project Brays’ channel widening does. Finally, based on the Meyerland case, we recommend the optimal flood mitigation strategies for similar flood-prone neighborhoods in the US.