In order to maintain the biotic integrity and performance of coastal marine ecosystems affected by human population growth and economic development an ecosystem approach to management is required. This is particularly challenging when, as is the case for many coastal ecosystems, development activities on land, often far removed from the coast, have a major impact on the coastal environment. The status of ecosystem management in the U. S. coastal zone is reviewed with a focus on four ecosystems heavily influenced by such landbased activities : the Chesapeake Bay, San Francisco Bay, the Mississippi Delta and Florida Bay. Ecosystem management in these cases requires dfficult decisions among the requirements for development (e. g. fresh water, flood protection, agricultural production, transportation, waste disposal, and building expansion) and environmental conditions in coastal waters. The Chesapeake Bay Program is a large and ambitious effort which is addressing control of diffuse sources of pollutants and the restoration of habitats with the aim of improving water quality and assisting the restoration of living resources. It enjoys strong public support and receives scientific and technical input through modeling and monitoring, yet it is only begiming to approach ecosystem management in a holistic sense. Linking environmental quality with living resources and better managing sprawling population growth in the watershed are vexing challenges. Based on this U. S. experience, science and engineering can make critical contributions toward ecosystem management through sustained investigation, developing clear evidence of the scale and causes of change, forging consensus among diverse technical experts, developing models to guide management actions, and identifying effective and feasible solutions.

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Numerous attempts have been made during the last four decades to develop techniques to delineate and assess the diverse habitats located throughout the United States. Delineation is a precursor to assessment and both are necessary prior to effective habitat management. Initial efforts to delineate habitats in the United States focused on application of classification techniques. Some classification efforts delineated all habitat types in the United States and displayed those boundaries on national maps whereas other classification efforts focused on particular habitat types such as wetlands. One technique incorporated vegetative, soil, and hydrologic characteristics to more precisely define habitat boundaries and satisfy the need for detailed boundary definition to regulate dredged and fill activities in wetland ecosystems. These classification and delineation techniques provided valuable tools to facilitate early attempts to assess habitat quality. Habitat assessment techniques also evolved to meet different geographic and technical requirements. Numerous techniques have been developed since the mid-1970s to assess a variety of habitats. The Habitat Evaluation Procedures developed by the U. S. Fish and Wildlife Service provides a national approach to wetland and non-wetland habitat assessment. Two other techniques, the Wetland Evaluation Technique and the Hydrogeomorphic Approach to Assessment of Wetland Functions, also provide assessment approaches which examined a wide range of wetland functions at both the national and local levels. The objective of this paper is to provide an overview of the evolution of habitat delineation and assessment in the United States with an emphasis on delineation and assessment of wetland habitats

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Wetland technology and englneermg provide the basis for extensive habitat restoration and creation in the United States. This includes habitats that are built without a requirement for regulation, and those habitats built for compensatory mitigation to replace impacted or lost wetlands. Wetlands are diffcult to restore and create due to their being living, dynamic, changing systems. However, the US Army Corps of Engineers and other agencies have been restoring and creating these habitats for over two decades using a variety of means. The Corps has identified, developed, and modified both engineering and environmental techniques and methodologies for accomplishing this work with some degree of predictability and success. Some of these technologies, the state- of-the-science, and some restoration and creation case studies are discussed. Each case study, regardless of the level of success, has provided valuable infomation (lessons leamed) that can be used to carry out future, similar projects.

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Characteristic relationship between rivers and safety in Japan is summarized at first to understand the background of river improvement works. Typical examples of existing facilities for the management of rivers are described with short history. Then social concem with environmental aspects related with rivers is described. It is shown that ecoIogical aspect becomes most important factor after the concept of 'sustainable development' and 'diversity of species'. Examples to enhance natural features in recent river works are studied and design principles for nature oriented river works are obtained.

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As we enter the 21st century three powerful forces are at work that will significantly increase public interest as well as private and public investing in ecosystem restoration. First, non-point source ecological health problems are emerging as the focus of 21st century environmental policy ; ecosystem restoration technologies are to these problems what pollution prevention and recycling technoIogies were to the point source human health problems targeted in the 20th century. Second, manufactured capital, the focus of nearly all 20th century investments, is being replaced by natural capital as the scarce factor of production. This is true in general, but is reaching alarming proportions in many developing nations where ecological infrastructures are already in desperate need of restoration. Third, and most important, the public and political will in developed nations to head off potential environmental problems before they occur has weakened with a growing preference for dealing with real problems as they ocuur. Demand, therefore, for restoration technoIogies, even though they are still in their infancy and have a poor record of success thus far, can be expected to grow significantly at the expense of pollution prevention technologies. In the near term the demand for restoration technologies will continue to be driven by regional 'quality of life' issues (e.g., endangered species and local fish and wildlife habitats) and regulations to deal with them, such as compensatory environmental mitigation. In time, what is leamed at the regional level will become the basis of new industries and markets for ecosystem restoration and strategically targeted species-level and habitat-level rehabilitation at different scales. Relevant technoIogies will be needed in four general areas : laboratory and infield technologies to restore features of ecological landscapes, and laboratory and in-field technologies to restore, or reserve options to restore, individual species and populations of fish and wildlife. This paper deals with the economic forces that will affect the growth and development of ecosystem restoration technologies and with ways of evaluating opportunities and constraints related to specific technologies and to specific types of restoration. It also summarizes conditions in environmental mitigation markets and the economics of what is being called environmental mitigation banking. The paper is based primarily on experiences with restoration businesses and markets that grew in the U.S. is a result of regulations requiring compensatory mitigation for wetland development impacts.

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The mitigation system, as it has been practiced in the United States over the past 20 some years, has not only contributed to enhancing and restoring habitats, but also to advancing our understanding of the ecosystem by leaps and bounds. It also engendered society's perception of the need for environmentally friendly lifestyle. All these gains owe, to a large extent, to the controversial section 404 clause in the Clean Water Act which imposes 'compensatory' mitigation on 'unfriendly' development activities. The mitigation system is here to stay, provided that it will continue to evolve toward eco-realism, eventually to become part of the sustainable lifestyle. The system in the years to come is envisioned to emphasize watershed-wide plaming, market forces in the form of mitigation banking and trust funds, among others, risk justification, economic impacts, easing of regulatory control, biodiversity, and performance monitoring of man-enhanced habitats.

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