FUTURE NEEDS FOR DEVELOPMENT 237 



Even if funds were unlimited, it would take years to complete 

 the work for any major drainage basin, because of the dearth 

 of trained ground-water hydrologists. 



Complete information concerning ground-water reservoirs, 

 however, is not necessary unless and until there is a prospect 

 that they will be developed for use. It is likely that some 

 ground-water reservoirs will never approach their develop- 

 ment potential, because water supplies from other sources are 

 more than adequate for the needs of the region. These reser- 

 voirs, however, may be important contributors to stream flow. 

 Records collected from observation wells in conjunction with 

 stream-flow records may show the extent of that contribution. 

 Such studies have enabled the Pennsylvania Water and Power 

 Company to forecast successfully the low-water flow of the 

 Susquehanna River, on the basis of records of water levels in 

 two dozen wells scattered over the 27,000-square-mile drainage 

 basin. 5 Analysis of these records indicates that the annual 

 range in ground-water storage throughout the drainage basin 

 is equivalent to about 3 per cent of the average annual stream 

 flow from the basin but that about 40 per cent of that stream 

 flow is water that has passed through the ground-water res- 

 ervoirs. In other words, the usable underground storage under 

 present conditions is drained and replenished many times in 

 the course of a year. 



inventory of water utilization. In most of the country 

 there is already some use of water, and a complete inventory 

 of the water passing through the hydrologic cycle would neces- 

 sarily include an accounting of the water already utilized. The 

 huge figures that describe the national "use" of water have 

 little meaning, unless they are accompanied by an analysis of 

 what the water is used for and what then happens to it. Nor 

 should water be designated "unusable" without saying what 

 it is unusable for, as might be shown by numerous examples: 



s Merriam, C. F., Interpretation of Natural Fluctuations of Ground Water 

 in Terms of River Flow, Jour. Am. Water Works Assoc, vol. 37, pp. 632-637, 

 1945; Ground-water Records in River-flow Forecasting, Trans. Am. Geophys. 

 Union, vol. 29, pp. 384-386, 1948. 



