Salish Sea Ecosystem Conference

Assessing restoration performance at the Nisqually River Delta: opportunity, capacity, and realized function

The restoration of the Nisqually River Delta represents one of the largest efforts toward re-establishing the ecosystem function and resilience of modified habitat in the Puget Sound, particularly for anadromous salmonid species. Here we use monitoring and applied studies to assess restoration performance within a tiered framework of Opportunity, Capacity, and Realized Function. Opportunity is evaluated with physical metrics for outmigrating salmon to access and benefit from the expansion of newly restored habitat. Capacity refers to specific functions of the restored habitats, such as the capacity to produce prey resources for outmigrating salmon. And realized function is the integration of Opportunity and Capacity metrics so that outmigrating salmon would benefit from accessing and foraging in newly restored habitats. We monitored and modeled a variety of physical parameters to measure changes in opportunity potential from historic, pre-restoration, and post-restoration habitat conditions at several sites across the delta. These parameters included channel morphology, water quality, tidal elevation, and landscape connectivity. Biological monitoring and applied studies included vegetation, invertebrate prey, salmonids, and waterbirds. Here we present synthesize the research results and publications to provide further insights to the ecosystem response to restoration processes.