(a) Individual reservoirs should be susceptible to reevaluation and modification during design stage in light of new techniques of water supply--including demonstrated feasibility and acceptability of the upper estuary for this purpose--and of water quality control, or unforeseeable modifications of aims or expected demands, should such change be determined to be beneficial to the overall well-being of the Basin. (b) Prior to construction of any reservoir with benefits for recreation and water quality downstream, responsible State and local agencies should be required to furnish assurances that the recreational and scenic qualities of the banks of the rivers so benefited will be amply protected. (3) By the continuing assessment by the Corps of Engineers of the water supply needs of the Washington metropolitan area with the objective of meeting future demands as they develop. (4) By research and investigation to ensure a sound scientific basis for future action in relation to the Basin's water resources and to provide maximum flexibility of choice to technicians, planners, and decision makers: (a) A full-scale and continuing water data collection program to be conducted in the Basin by the U.S. Geological Survey, with the object of building and keeping up to date the facts relevant to the river system and related aquifers. (b) Specific and continuing research by the Department of the Interior as well as other agencies into the nature and feasibility of a full range of possible alternative sources of water supply in the Basin, including new technological approaches. (c) A special study should be made, based on extension and coordination of studies now authorized or under way to determine the feasibility and acceptability of using the upper estuary as a future source of domestic water to supplement the water supply for the metropolitan area. The States of Maryland and Virginia, the District of Columbia and the Metropolitan Council of Governments should also be associated with this study. b. To begin to cope with major or general flooding problems in the Basin and to prevent future potential flood damages, the following actions should be taken: