In terms of metropolitan Washington's water supply, considered apart from other Basin water problems, the best reservoir site by far in the whole Potomac drainage would be the old River Bend site or the one proposed in 1963 at Seneca, both just upstream from the Falls above the metropolis. In one package, either of them would impound enough water to take care of any likely municipal and industrial demands of the metropolitan region for more than a half-century, besides trapping most silt from upstream to keep it out of the estuary, and providing a good measure of protection for flood-susceptible metropolitan shores. Furthermore, the proximity of such a reservoir to the city would ensure a great deal of aquatic recreation for people there and would somewhat simplify water management problems. Thus, it is natural that Seneca, the latter proposal of the two, has found strong champions among metropolitan administrators, water engineers, and planners whose thinking has to be primarily in terms of sure and efficient water supply and flood protection. It has found equally strong opponents, however, enough of them to have stalled it to date. It is not yet dead, for it emerges in each new discussion of the city's water situation. It will not be dead until the metropolitan water problem, short-term and long-term both, has found a full satisfactory solution in other terms. Our feeling remains unchanged since the publication of our _Interim Report_: that when all factors are weighed and future uncertainties are taken into account, Seneca should not be built at this time. If the price in money would not be high in relation to immediate "market" advantages gained, the permanent price, in river and countryside and those other intangibles that are getting to have more and more weight in men's minds year by year, would be heavy.