Rainfall in the Virgin Islands averages about 44 inches per year, yet fresh water is in short supply, and the general impression of the islands is one of dryness. Land slopes are steep and runoff from rainstorms flows rapidly to the sea in the numerous, short, steep stream courses. During most dry seasons only a few streams maintain flow along any part of their course. Guinea Gut, the only stream in St. John known to have had continual flow during the first half of 1963, had a minimum flow of 3,500 gallons per day (gpd). The flow of Turpentine Run, the largest stream in St. Thomas, dropped to 15,000 gpd during the same period, and the flow of River Gut, the largest stream in St. Croix, dropped to about 70,000 gpd. In past years the flow of the streams has been less at times; in fact, Turpentine Run reportedly did not flow during part of 1923 and probably it has been dry at times since then. The streams thus are not reliable sources of large water supplies unless storage is provided. The building of reservoirs has been discouraged by several factors including the apparent scarcity of good sites, the lack of appreciable stream flow most of the time, and the large amount of sediment carried by the streams during floods.
