Projecting Cumulative Benefits of Multiple River Restoration Projects: An Example from the Sacramento-San Joaquin River System in California

Abstract

Despite increasingly large investments, the potential ecological effects of river restoration programs are still small compared to the degree of human alterations to physical and ecological function. Thus, it is rarely possible to "restore" pre-disturbance conditions; rather restoration programs (even large, well-funded ones) will nearly always involve multiple small projects, each of which can make some modest change to selected ecosystem processes and habitats. At present, such projects are typically selected based on their attributes as individual projects (e.g., consistency with programmatic goals of the funders, scientific soundness, and acceptance by local communities), and ease of implementation. Projects are rarely prioritized (at least explicitly) based on how they will cumulatively affect ecosystem function over coming decades. Such projections require an understanding of the form of the restoration response curve, or at least that we assume some plausible relations and estimate cumulative effects based thereon. Drawing on our experience with the CALFED Bay-Delta Ecosystem Restoration Program in California, we consider potential cumulative system-wide benefits of a restoration activity extensively implemented in the region: isolating/filling abandoned floodplain gravel pits captured by rivers to reduce predation of outmigrating juvenile salmon by exotic warmwater species inhabiting the pits. We present a simple spreadsheet model to show how different assumptions about gravel pit bathymetry and predator behavior would affect the cumulative benefits of multiple pit-filling and isolation projects, and how these insights could help managers prioritize which pits to fill.

Assessment Approach for Identifying Compatibility of Restoration Projects with Geomorphic and Flooding Processes in Gravel Bed Rivers

“…This strategy is consistent with Wohl et al's (2005) key criterion that methods of restoration should be effective under existing constraints, because it leads directly to specifying project types that are compatible with the existing local and reach-scale processes. This scheme will also be more productive in the near term instead of attempting to restore natural processes that create and maintain habitat at the catchment scales recommended by Roni et al (2002), which may not always be possible under existing constraints (Wohl et al 2005;Kondolf et al 2008) and will inherently take much longer.…”

Is habitat restoration targeting relevant ecological needs for endangered species? Using Pacific Salmon as a case study

“…That cost is a significant driver of decision making is not surprising however. Social constraints such as landownership, public acceptance, and funder priorities influence project type and placement (Halle 2007, Miller and Hobbs 2007, Kondolf et al 2008, Christian-Smith and Merenlender 2010.…”

“…In light of the lack of coordination across the restoration enterprise , Kondolf et al 2008, there is a critical need to evaluate how well habitat restoration actions match the impaired habitat conditions, especially when targeting a threatened or endangered species like Pacific Salmon. Such evaluations establish accountability for the use of public and private funds and establish reasonable performance expectations for the considerable efforts and resources applied to restoration (G.A.O.…”

“…Despite this extraordinary financial investment, projects to restore freshwater and estuarine habitat are assessed for effectiveness at the individual project level rather than in the context of the greater recovery efforts, if post-project monitoring is funded at all (Bash and Ryan 2002). Many projects are funded piece-meal by various administrative units based on the priorities of the funding agency, availability of funds, ease of implementation and buy-in by landowners and stakeholders rather than needs outlined in management plans (Miller and Hobbs 2007, Kondolf et al 2008, Katz 2009). Indeed, in 2002 the U.S. Government Accountability office estimated that 66% of non-mainstem and nonhatchery federal expenditures (i.e., the fraction available for habitat restoration and protection) were distributed directly to local, non-Federal entities for salmon recovery management (US $537.2M from 1997(US $537.2M from to 2002G.A.O.…”

Evolution of Two Urbanized Estuaries: Environmental Change, Legal Framework, and Implications for Sea-Level Rise Vulnerability

“…After the enactment of the McAteer-Petris Act of 1965 (see next section), landfilling was halted. Wetland restoration efforts have ensued and, especially since the implementation of Bay-wide ecosystem restoration targets [18], the purchase and restoration of several salt ponds has allowed for a steady increase in the provision of habitat [18,57,93,94,98] that culminated in the ongoing South Bay Salt Ponds Restoration Project [99].…”