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is probably a lag of more than one year "between increases or decreases in precipitation and rises or declines of the water level. The steep, marked decline during 19UU is undoubtedly the result of increased with­drawal from the aquifers combined with a decline in precipitation dur­ing 19^2 and 19H3, It is possible that this steep decline indicates that water was being withdraw from storage during the period of incfeased discharge, and that the amount of water which can be safely pumped without injuring the aquifers has been exceeded. Further study must be made of the physical characteristics of the aquifers and of recharge and discharge conditions in the valley to determine ttfhether or not this condition has been reached. There is probably natural discharge to the water table from the.artesian aquifers (Page 1$). If this is true, further pumping would decrease the amount of water lost by natural discharge and increase the amount of water now avail­able from the aquifers. At the present time, this is the only apparent way to increa.se recharge of a considerable amount of water to the points of. withdrawal* Sufficient data is not yet available to esti­mate the total recharge to the area. Studies are now under way to determine the geological conditions and the amount of precipitation in the recharge area, and the avail­ability of procipitation to the aquifers. Yield of wells: The aquifers act both as storage reservoirs and as conduits to transmit the water from the areas of recharge to points of withdrawal. Storage capacity of the aquifers depends upon their vertical and horizontal extent and upon the amount of pore space in the material. The rate at which water flows through the materials of the aahifers depends upon their permeability, their cross-sectional area, and their hydraulic gradient. The yield of wells, therefore, is limited by these factors as well as by the amount of recharge available. The permeability of the water-bearing materials is estimated to range from less than 500 to more than 2,000 (gallons a day per square foot of cross-sectional area with a hydraulic gradient of 100 percent), the less permeable parts of the aquifers occurring east, and the more permeable parts in and west of the artesian spring zones. Numerous laboratory and field pumping tests to determine more accurately the permeability of the water-bearing materials have been planned and will be made in the near future. Cross-sectional areas through which the water must flow may be determined in general from the logs of the wells in the valley. Hydraulic gradients from the areas of recharge to the points.of withdrawal can be determined from the difference in water level at these points. Yields of the wells in las Vegas Valley range from a few gallons a minute to about 2,000 gallons a minute. Specific capacities (gallons a minute per foot of draw-down of water level after several hours of flow ar pumping) recorded for numerous wells range from 120 to less