Male Chinook Salmon. Photo: Barbara Rich / Getty Images .

SEI’s Water Evaluation And Planning (WEAP) system has been used for more than a decade to model the operations and aquatic habitat in the Fisheries and Aquatic Habitat Collaborative Effort (FAHCE ) with the Santa Clara Valley Water District. The model is being used to evaluate utility reservoir reoperations to better project downstream habitat for local aquatic species.

To support this project, SEI developed the Aquatic Habitat Assessment (AHA) plugin for WEAP to evaluate the habitat suitability of native aquatic species. Information on stream hydraulics, utility operations, local demands and biological needs of species are all integrated in the WEAP model. The AHA plugin was used to compare the habitat suitability of local Chinook salmon and steelhead trout in the Three Creeks watershed of Santa Clara County under alternative reservoir reoperation scenarios. A Tableau dashboard was used to visualize the model results of both human water supply and aquatic habitat under alternative reservoir reoperation scenarios.

The results were ultimately used to unite a range of conflicting parties to refine and ultimately reach consensus on a common solution for a set of reservoir reoperations which best optimize and balance limited water supplies for human use and aquatic habitat, helping the district to meet California Environmental Quality Act requirements. Recently, the model has also been used to predict the effects of reservoir retrofit construction on downstream water temperature, informing a local fish rescue effort in June 2021.

California Instream Flows: Presentation from the 2019 SEI Science Forum

WEAP Plugin for Aquatic Habitat Assessment