Conjunctive Management Analyses for Endangered Species Flow Augmentation Alternatives in the Snake River

The U.S. Bureau of Reclamation's (Reclamation) Pacific Northwest Region is working to enhance the ability to integrate surface and ground water hydrological and institutional modeling capabilities for use in the Snake River Basin and other river systems in the Pacific Northwest. The MODSIM model is a generalized river basin network flow model which is capable of distinguishing between natural flow and various storage contract arrangements for water entitlement accounting, including storage ownership, water service contracts, and rent pool/water banking. The USGS MODFLOW groundwater model is applied to the vast East Snake River Plain Aquifer to analyze the long term impacts to groundwater discharge to the Snake River. MODSIM and MODFLOW are applied to the Upper Snake basin to quantify how much water reallocation is needed to accomplish flow augmentation objectives. River and reservoir operation simulation analysis is used to quantify impacts to irrigation water supply, river and reservoir recreation, resident fish and wildlife, and other local water uses from various proposed storage rental and reallocation scenarios for satisfying instream flow requirements for endangered species.