Watearth was commissioned to complete a drainage study for the Morrison Creek Watershed and Winding Meadow Village development on 65th Street Expressway. Involved with 2D and unsteady flow modeling of storage areas and crossings. XP-SWMM model of closed conduit storm drain system. The study includes a storm drain analysis for the site for overland release through proposed streets and overland release structure and a hydraulic analysis to model existing and proposed floodplain and determine floodplain impacts. The drainage study was requested to satisfy the drainage study general requirements from the Sacramento County Department of Water Resources. Watearth conducted updates to the 100-year and 200-year hydrology in existing conditions HEC-RAS models provided by the County. The overall purposed of the project is to determine whether the storm drain outfalls from the site into the canal cause impacts to downstream neighbors, to evaluate on-site storm drain system and HGLs, and to prepare a drainage study. Mitigation was achieved by creating a 100-year flow path through the roadways (max one-feet deep) and providing detention in the park, which is required to drawdown within 24 hours of a 100-year event. Updated terrain file with as-built topographic data to confirm if grading revisions were need to meet flood plain management requirements related to hydraulic impacts.