Sentence:  In view of the increasing shortage of usable <WSD>surface</WSD> and ground water in many parts of the Nation and the importance of finding new sources of supply to meet its present and future water needs , it is the policy of the Congress to provide for the development of practicable low-cost means for the large-scale production of water of a quality suitable for municipal , industrial , agricultural , and other beneficial consumptive uses from saline water , and for studies and research related thereto . 
Meaning of the word marked with <WSD> tags:  the outermost level of the land or sea