Interagency Ecological Program: Monitoring of water quality, phytoplankton, zooplankton, clams, and Delta Smelt to support the Summer-Fall Suisun Marsh Salinity Control Gates Action 2018-2024

The Suisun Marsh Salinity Control Gates (SMSCG) have the potential to increase low-salinity-zone habitat for endangered Delta Smelt (Hypomesus transpacificus, California Endangered Species Act listed as Endangered, Federal Endangered Species Act listed as Threatened), and to allow them to more frequently occupy Suisun Marsh, especially Montezuma Slough, one of their most important rearing habitats. Operation of the SMSCG in summer and fall to improve Delta Smelt habitat are called for in the Biological Opinion and Incidental Take permit for the Central Valley Project and State Water Project.

To support the adaptive management of the action, the California Department of Water Resources and collaborating agencies monitored water quality, phytoplankton, zooplankton, clams, and fishes during the SMSCG management actions in 2018. Monitoring has continued during the summer and fall months of all subsequent years, including both those with and without actions. This data package includes data collected by the Interagency Ecological Program’s (IEP) long-term monitoring programs supplemented with targeted sample collection where existing surveys lacked spatial or temporal coverage.