FUTURE NEEDS FOR DEVELOPMENT 229 



the most effective development of the ground-water resources. 



With so little knowledge of the ground-water resources, it 

 is inevitable that those resources are generally neglected in the 

 "integrated" development of all water resources of major 

 drainage basins. Thus the program for Tennessee Valley is 

 dominantly one of river development for power, navigation, 

 and flood control, and records of stream flow and precipitation 

 furnished the basic data for the program. The program of 

 more effective land use, with its advantages of decreased soil 

 erosion and increased storage of soil water, has subsequently 

 become increasingly important. It is estimated that ground 

 water contributes an average of 50 per cent of the annual flow 

 of the streams and that some rocks are so permeable that 

 abundant water supplies flow through them, in some instances 

 carrying sediment and bacteria, so that there are serious prob- 

 lems of ground-water pollution. But so little is known about 

 ground-water occurrence that the obtaining of adequate sup- 

 plies from wells is largely a matter of chance, and there is still 

 no basis for evaluating ground-water reservoirs as integral 

 parts of the Tennessee Valley's Avater economy. 



Similarly in the Missouri Valley the authorized plan for 

 development is a stream-development program. Programs for 

 land use were proposed subsequently, and the ground-water 

 potentialities are still very little known. In the Columbia 

 Basin, available basic data are generally agreed to be sufficient 

 to justify the dams already under construction; but we do not 

 by any means have the information fundamental to a deter- 

 mination of the best program of water-resource development 

 to meet local, regional, and national needs. In general, for the 

 comprehensive river-basin programs already formulated, the 

 ground-water reservoirs will not be an integral part but an 

 afterthought which must fit into a program otherwise well 

 along in the design and construction stage. 



A major factor in the successful production of ground water 

 for use is the "know-how" of the technicians who are primarily 

 responsible for the development and maintenance of produc- 

 tion. In the past two decades there have been great advances 

 in the technical knowledge, procedures, and equipment used 



