128 CONSERVATION OF GROUND WATER 



some recharge at times of heavy precipitation, simply because 

 storage space in their recharge areas is used up. The problems 

 of declining water levels and in some places of resulting saline 

 encroachment are, therefore, due chiefly to the slow transmis- 

 sion of water from these recharge areas to the points of use. 

 Artificial recharge from ponds has been attempted with 

 marked success by the Perth Amboy Waterworks and the 

 "Duhernal" companies (du Pont, Hercules Powder, National 

 Lead). By ponding stream flows, it has been possible to add as 

 much as 15 million gallons a day to a ground-water reservoir 

 in Middlesex County. 



Atlantic City, N.J. 5S Atlantic City is justly proud of its 

 salt-water attractions and has long been aware of the pos- 

 sibility of contamination of its fresh-water supplies by the 

 salt water. Ground water, which has always been the pre- 

 dominant source of supply, has been studied intensively, 

 and since 1923 careful watch has been maintained to detect 

 any encroachment of salt water into the fresh-water supplies. 



The city has obtained its ground-water supplies from 

 three aquifers. The shallowest ("100-foot sand") is most sus- 

 ceptible to salt-water intrusion, for it lies at rather shallow 

 depth beneath salt-water marshes and lagoons. Three of the 

 five municipal wells drilled in this aquifer in 1930 were 

 abandoned shortly thereafter because of inflow to the wells 

 from nearby salt marshes, and other wells in the aquifer are 

 generally held in reserve and pumped only to meet peak 

 demand. The next deeper aquifer ("200-foot sand") fur- 

 nishes a large proportion of the water supplies, particularly 

 from wells near its recharge area, which are farthest from 

 salt water. 



The principal aquifer at Atlantic City is the deep ("800- 

 foot") sand. On the mainland this aquifer yields water of 



58 Reference: Barksdale, H. C, R. M. Sundstrom, and M. S. Bronstein, "Sup- 

 plementary Report on the Ground-water Supplies of the 

 Atlantic City Region," New Jersey State Water Policy Com- 

 mission Special Rept. 6, 1936, 132 pp. 



