Upper Green River Storage, Level II Study

This project involved investigation of water storage options in the Upper Green River Basin from the headwaters to Fontenelle Reservoir.  Leonard Rice Engineer’s responsibilities for the Wyoming Water Development Commission included reviewing the initial irrigation shortages estimated in the Green River Plan and determining environmental opportunities and permitting constraints.

Leonard Rice Engineers revised the shortages estimation based on a longer study period that better illustrated the variability of monthly and annual crop demands and available hydrology.  A StateMod water resources planning model was developed using information from the Green River Basin Plan spreadsheet model and earlier WIRSOS modeling efforts. Irrigation demands were assigned to river nodes in the stream network model to organize the relative locations of demands and streamflows above Fontenelle Reservoir. Water permits associated with river headgates were included in the model and river diversions were simulated to meet irrigation demands based on the physically available flow subject to the water available to the water permits in priority.

Prospective reservoir sites were identified based on excess legally available flows simulated in the prior appropriation model. Junior storage rights were added for promising reservoir sites and simulated with reservoir releases to alleviate irrigation shortages. Environmental evaluations were conducted on the future reservoir sites to highlight key environmental issues, including the presence of wetlands and riparian habitats and endangered, threatened, and sensitive species. Other unique characteristics of reservoir sites were identified to highlight potential permitting and environmental issues that may need to be addressed as part of future reservoir construction projects.