Informing watershed planning and policy in the Truckee River basin through stakeholder engagement, scenario development, and impact evaluation

In this study, we evaluated the water quality and quantity impacts of five restoration and land protection scenarios in the Truckee River watershed, in the context of regulatory goals. We used spatially explicit biophysical models to create scenarios with targeted places where the greatest water quality and supply benefits could be realized. We quantified how these scenarios would impact the sediment load, nitrogen load, phosphorous load, and annual water yield with hydrologic models. The scenarios included a “Business as usual” based on existing conservation plans (2015–2020) and four additional model-generated scenarios: a “Targeted” scenario using the “Business as usual” budget, two targeted “Increased budget” scenarios, and a “Targeted-climate smart” scenario adjusted based on climate change. We expected the model-generated scenarios to have a greater impact on biophysical factors than “Business as Usual,” and that the “Increased budget” scenarios would reach water quality regulatory goals. The “Targeted” scenario produced a small improvement in water quality over “Business as usual,” but did not meet regulatory goals. The “Increased budget” scenarios could meet water quality goals in one additional subwatershed if the budget is allocated to the most cost-effective activities to reduce sediment. Incorporating climate change caused the targeted locations of activities to shift in space, but the overall impact on biophysical factors was similar. This study demonstrates how science-based planning with stakeholder input can inform conservation investments across existing boundaries and lead to greater water quality improvements. By identifying where to implement different types of conservation activities and how much to invest, as well as revealing shortcomings in current assumptions about which activities to implement, this study can enable smarter and more effective land management investments.