EPA's Water Quality Modeling Workgroup is hosting a series of webinars to help water quality professionals better understand surface water quality modeling and how models can be used to solve common problems that face water quality regulators. The webinars are focused on modeling as it applies to the Total Maximum Daily Load (TMDL), Standards, and Water Quality Permitting Programs, but they are applicable to a wide range of audiences. These two-hour webinars cover everything from modeling basics (e.g., model setup and calibration) to applied water quality modeling of different pollutants. This webinar will introduce SWAT+, a watershed model that has been applied to a wide range of hydrology, water quality, land use, and land management problems. SWAT was developed jointly by USDA-ARS and Texas A&M and has contributed to more than 4,000 peer-reviewed publications.