Concerning the physical availability of water in southwestern Virginia for a prospective coal slurry pipeline, a preliminary investigation was undertaken to determine the capacity requirements for offstream-type reservoirs dedicated to pipeline use only. Offstream-type reservoirs were considered in view of their several apparent advantages, such as minimum interaction with the normal environment of the stream, and that its operation would probably be left entirely to the pipeline management. Five local streams in the vicinity of the probable pipeline origins were considered in this study. The calculations were made according to several different scenarios conceived for future application to diversion from the stream. Each scenario assumes a series of different diversion rates from the stream when the stream discharge is within different fractional ranges of the mean discharge. Also considered as constrains in these calculations is a series of alternatives for the maximum diversion rates allowed from the stream at any time, to account for the capacity of the diversion or intake structure, as well as that of the conveyance line between the intake and the reservoir, as the latter would not probably be located directly next to the intake structure. These capacity alternatives were based on the predicted continuous demands of the pipeline with various annual throughputs. Mass curve analysis was used in the determination of a reservoir that will guarantee the continuous supply of water for the coal slurry pipeline during the whole period considered. The study was further complemented by determining the reliability characteristics of smaller-size reservoirs in terms of their recurrence intervals based on a partial duration low-flow series analysis. / M. S.