A. Determination of what aquifers are available under a given point on 

 the island and the approximate depths to each. 



B. Studies of the hydrology of each aquifer by itself and determination of 

 the points of recharge, discharge and interconnection. 



C. Study of the safe yields of the various aquifers, how best they may be 

 developed and what restrictions must be placed on the drafts upon each. 



D. Studies of water levels and the fluctuations thereof, salt water pene- 

 trations, chemical quality, temperature and whatnot. 



Years ago it was held generally that the ground waters of Long Island were practically 

 a unit and should be considered as such (GW-2 — Fig. 12) (14) . It is now well established that, 

 although many and perhaps all of the aquifers have points of hydrologic intercommunication, 

 they must be considered as essentially separate entities, particularly for hydrologic studies. 

 Serious errors have resulted in attempts to draw contours of the ground water surface, lines 

 of equal salinity and of temperature in which no distinction as to aquifers has been made. 



At present when a proposed well is under consideration, it is usually necessary to make 

 quite an elaborate study of known nearby wells, vertical sections through the proposed well, 

 and by other means to try to determine from what aquifer it will draw water and what wells 

 or points of recharge and discharge will be affected by pumping from the proposed well and 

 the magnitude of the effects. This process has been repeated for practically each new well. 

 Although it is certain that the data available for the geologic determination of the aquifers are 

 insufficient in quantity, the wells poorly located for the purpose and the logs deficient in 

 precision, it is thought that the united efforts of all the men most versed in the subject and 

 covering the entire island will produce results far more dependable than those resulting from 

 such scattered effort, and much time will be saved in having this general study available for 

 all proposed wells. 



It is contemplated that as new facts come in, they will be plotted on the maps and profiles 

 contained in this Bulletin and suitable corrections in such maps and profiles made. As long as 

 a continuous study is projected, it appears that the true facts eventually will emerge and 

 that no one should be led astray by erroneous tentative deductions from inaccurate data. 



Some are of the opinion that this work is premature. Perhaps, it would be if this were 

 a scientific geologic study. The immediate situation demands action by the Commission now. 

 It would stop all well sinking for decades to wait for additional and more precise data, and 

 if the Commission were to try to do so, it would, by that very act, prevent the further 

 accumulation of data. 



Particularly in view of the fact that hydrologic studies are urgently needed and that they 

 are more or less impossible unless the limits of the various aquifers are at least partly known 

 and can be reasonably assumed in their entirety, the Commission is justified for this purpose 

 in going some distance outside of the established data. The assumptions necessary constitute 

 a gross case of extrapolation. This, of course, is always dangerous and to be avoided as far 

 as possible, but apparently must be done as a first approximation in making the hydrologic 

 studies. As these progress, their theoretical determinations will be tested, corrected and 

 changed. 



In view of all these facts the Commission stated the above problem and made arrangements 

 to have this Bulletin prepared. 



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