THE PROBLEM 



Based on the geologic and other data now available to show graphically the various aquifers 

 and other formations making up Long Island, this to be done in such manner as to facilitate 

 the work of the Commission in the regulation of use of Long Island ground waters. 



To conserve and apportion the available ground waters of Long Island, particularly with 

 regard to the present and future needs of the people of that island for water for domestic 

 purposes, the Legislature has required that the Commission be advised of the sinking of virtu- 

 ally all wells on the island and that the permission of the Commission must be obtained before 

 most large capacity wells may be put down. 



To enable it properly to perform these duties, the Commission, for over sixteen years, 

 has been accumulating data with regard to wells and ground water conditions on the island. 

 In this work it has been greatly aided by the cc operative work of the United States Geological 

 Survey, the cost of which work is shared by the Federal Government, the State of New York 

 and the counties of Nassau and Suffolk. 



By direction of the Legislature, the Commission in 1937 published a preliminary report 

 on these matters (GW-2) . As part of or in continuation of that study up to the present time, 

 the following has been done: 



Data on all discoverable wells have been collected, the wells given official numbers and 

 plotted on record maps, and the data have been filed and indexed for reference. 



Water levels in many wells have been measured and the results published annually by 

 the Survey. 



All available well logs have been collected and such of them as appear to be reliable have 

 been edited by the Survey and published in Bulletins GW-3, 4, 5, 6, 8, 9, 10 and 11. 



Considerable data have been collected on the salinity, hardness and temperature of the 

 ground water, interference between wells, rainfall affecting ground water and many other 

 matters, some of which are the subject matter of certain of the bulletins in the GW series. 



The rock floor under the island was partly mapped by the Survey and published as 

 Bulletin GW-15. This map, as extended, is republished herein. 



As the basis for this work, the Survey has correlated, as far as possible, the available 

 well logs and determined the elevations of the surface of the various aquifers and other geologic 

 formations. This information for Kings county was published in Bulletin GW-17. The data in 

 that Bulletin, amended and extended, are included herein so that, as to that particular subject, 

 this Bulletin is complete. 



All this material is available to the Commission and to the public, but it is not in a form 

 convenient for many uses, and without rearrangement not too convenient for important studies 

 which must be undertaken. Some of these are : 



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