- When proposed for permitting under the terms of the Clean Water Act (CWA) §404 and Endangered Species Act (ESA) §7 and §10 programs, many transportation, infrastructure, and development projects would cause impacts to wetlands, streams, and the habitat of sensitive species. In these cases, state and regional transportation agencies work with Federal and state regulatory agencies to avoid and minimize adverse impacts to aquatic resources and habitat. After impacts to aquatic resources and habitat are avoided and minimized as much as possible, transportation agencies are commonly required to compensate for unavoidable impacts to these resources. Compensation, or compensatory mitigation, can be an important method of maintaining healthy, economically valuable ecosystems.
In this handbook we provide an overarching view of the ecosystem and economic benefits and cost savings associated with progressive approaches to the Clean Water Act or Endangered Species Act compensatory mitigation and com-pare these benefits and savings to traditional mitigation approaches. We then highlight several empirical examples of transferable tools, models, and frame-works used for innovative compensatory mitigation in use throughout the United States. We highlight innovative tools, methods, and frameworks that focus on landscape or watershed analysis of ecosystem functions only, as well as progressive approaches that include the valuation of ecosystem services provided by compensatory mitigation. Finally, we lay out tangible steps for transportation agencies, policy-makers, and the research community to facilitate and implement progressive mitigation programs. More detailed information about some important technical terms are provided in call-out boxes throughout the handbook, and a glossary of terms is provided in Section 6.