The provisional natural flow is an early estimate of natural flows at the Colorado River at Lees Ferry, AZ. It is provided to give water operators and stakeholders insight into the natural flows since the most recent published year. Estimates depend on Reclamation's 24 Months Study and are published following the completion of the January, April and August studies. Estimates are developed from either the historical unregulated inflow or the forecasted unregulated inflow into Lake Powell from the Colorado Basin River Forecast Center (CBRFC). Estimates from previous studies are provided to help users understand the evolution of the provisional natural flow. Provisional data are not used for modeling purposes in CRSS.