When is Aquatic Resource Type Conversion Appropriate: A Framework for Cleaning Sand out of the Gears and a Case Study for McInnis Marsh

Abstract

Wetland and stream restoration projects may sometimes involve converting one “type” of aquatic habitat to another “type” (e.g., managed salt ponds into tidal marshes, depressional wetlands into streams, marsh into transition zone habitat). This “type conversion” may be necessary and beneficial in the context of addressing watershed plans or regional restoration goals, or in achieving resiliency to climatic changes (Goals Project 2015). Conversion can also occur through other large-scale, complex actions (e.g., mitigation banking initiatives). Whether driven by habitat restoration goals or compensatory mitigation needs or both, regulatory oversight typically governs the process. Holistically assessing such conversion through the regulatory lens is challenging for permitting programs. To address this challenge, an interagency team of federal and state regulators and resource managers in California developed a structured and transparent approach for evaluating the appropriateness of aquatic resource type conversion. The resulting framework can support project planning and inform regulatory evaluation by helping to answer: 1) what loss or gain of function is expected from various aquatic resource type conversions, and 2) whether conversion might be ecologically (or functionally) appropriate. The intent is to support agencies’ technical and regulatory decisions by providing a standardized, transparent set of tools and approaches that can inform discussions between agencies and with project proponents during the project evaluation phase, with a goal of ensuring that projects are not only permittable, but environmentally beneficial.