Green River Basin Transit Loss Evaluation – Wyoming State Engineer’s Office

Follum Hydrologic Solutions (FHS) in collaboration with Precision Water Resources Engineering (PWRE) completed a comprehensive transit loss evaluation for the Green River Basin on behalf of the Wyoming State Engineer’s Office. The project addressed Wyoming’s need for improved, defensible water accounting in support of Colorado River Compact administration and long-term water management. The study initially focused on the Upper Green River Basin upstream of Fontenelle Reservoir and was later expanded to include the Green River downstream to the Green River gage at Green River, Wyoming. FHS delivered a multi-decade (1991–2023) water balance analysis that integrated observed gaging records, reconstructed streamflow, and satellite-derived evapotranspiration data to quantify reach-scale losses associated with bank storage, riparian evapotranspiration, surface evaporation, and groundwater interactions.