Linkage of River Operations, Watershed, and Water Quality Modeling to Support a Truckee River Third-Party Nutrient TMDL Review and Revision

Three advanced modeling tools were applied and linked to assess the water quality response of the Truckee River under varied flow conditions, in support of a third-party total maximum daily load (TMDL) review and revision. The Truckee River Hydrological Simulation Program FORTRAN (TRHSPF) is an in-stream water quality model that predicts occurrences of low dissolved oxygen resulting from benthic algae, and low flow. TRHSPF inputs include projected flows and diversions as generated by a water operations model, and tributary flows and nonpoint source loads from a watershed model. The Truckee River Operations Model (TROM), a water operations model, projects regulatory flows (reservoir releases, diversions) with and without different flow management strategies in place. The Watershed Analysis Risk Management Framework (WARMF), a watershed model, forecasts nonpoint source loads under current and future land use. The three linked models, run together under various flow management scenarios, provide an understanding of how the Truckee River system assimilates nutrients and complies with water quality standards.