Forecasting the magnitude of sustainable biofeedstock supplies is challenging because of 1) myriad potential feedstock types and their management; 2) the need to account for the spatial variation of both the supplies and their environmental and economic consequences; and 3) the inherent challenges of optimizing across economic and environmental considerations. Over the last two decades, US biomass forecasts have become increasingly complex and sensitive to environmental and economic considerations; however, more model development and research is needed. In particular, the landscape and regional tradeoffs of differing biofeedstock supplies need to be addressed, especially with regard to water quality concerns and wildlife/biodiversity. [...]