The Gridded Surface Subsurface Hydrologic Analysis (GSSHA) model is an integrated system of physics-based hydrologic process models. This approach of using a system of physics-based models allows GSSHA to be a good fit for many watershed management decision support applications, such as understanding changing flood dynamics from urban growth as well as using natural and nature-based solutions, such as wetlands or artificial beaver dams, to ameliorate flooding potential. One of the key roles GSSHA has played is modeling compound coastal storm flooding – extreme rainfall combined with storm surge from tropical systems. Simulating such events requires coupling of overland, riverine, coastal, and weather modeling systems. A challenge facing the USACE modeling community is enabling the programmatic connections between models to reduce manual input errors and increase the throughput in time-sensitive situations. In this talk we will discuss how GSSHA has been modernized to enable programmatic-level access to GSSHA. This allows GSSHA to be used in systems of computational models as well as opens up GSSHA to a wide level of data science integration applications, particularly as a part of the NextGen Framework.