Aquatic ecosystems perform many valuable environmental functions. They recycle nutrients, purify water, reduce flooding, enhance and maintain river flow, regenerate groundwater, provide wildlife habitat and human recreation. Many parts of the United States The rapid population growth in , along with increased industrial, commercial and residential development, has resulted in the contamination of surface waters with fertilizers, pesticides, motor oil, toxic landfill leachates and livestock manure. Concurrently with increasing water pollution and the release of nutrient-laden urban wastewater, water usage is also increasing, reducing the flow available for waste dilution. Increased sediment input from urban development, agriculture and forestry also leads to increased turbidity and sedimentation of downstream canals, lakes and reservoirs, resulting in water storage and transport capacity, recreational and aesthetic value, fish habitat and game abundance. The increased demand for wetland drainage was taken into account. National Academy of Sciences, Academy of Engineering and Medicine, Aquatic Ecosystem Restoration: science, technology and public policy. Hydrographic changes lead to further loss of river habitat, resulting in the extinction or endangerment of aquatic organisms, affecting many useful water uses such as drinking, swimming and fishing. Aquatic ecology Public and private decisions to manage systems have improved water transport, developed hydroelectric power plants, reduced flood risk, and provided water for cities, industry, and agriculture. But these activities have also changed the physical, chemical, and biological processes involved in aquatic life. The Commission believes that public opinion in the United States is strongly supportive of increasing environmental concern. State investment in various types of environmental programs is important, but piecemeal and not always effective. Efforts to restore and conserve the environment need to be accelerated. The Commission believes that a comprehensive and positive restoration component should be at the center of such efforts. The premise of this report is that ecological restoration of aquatic ecosystems is possible. Restoration means bringing the ecosystem closer to its pre-collapse state. Achieving restoration means restoring or restoring ecosystem structure and function to ensure that natural dynamic ecosystem processes can function effectively again. However, recovery may be impractical or undesirable. B. When waters naturally devoid of fish have been successfully converted into valuable trout fisheries by stocking, or when significant urban development is located on wetlands. In such cases, the Commission recognizes that the economic value of these developments may hinder attempts to restore existing natural systems at these sites. The Commission also recognizes that preventive measures are important to protect aquatic ecosystems, and that preventive measures that benefit multiple parts of the water cycle should be prioritized. If the environment was well protected in the past, there is no need for many costly restoration projects today. Of course, restoration of aquatic ecosystems is gradual, and certain ecosystem functions and characteristics, such as drinking water, can be restored even when other ecosystem characteristics deviate from natural conditions. Therefore, in certain circumstances, partial ecological recovery may become the goal of operational management and provide significant ecological benefits, even if full recovery is not achieved. Multiple responsibilities at all levels of government that affect fish stocks need to be better coordinated in order to conduct large-scale recovery efficiently and effectively.