Report Title: A preliminary appraisal of the Garber-Wellington aquifer southern Logan and northern Oklahoma Counties Oklahoma
Minimum recharge to the aquifer in 1975 is estimated to be 190 acre-feet per square mile or about 10 percent of the annual precipitation. Total minimum recharge to the aquifer in the study area in 1975 is estimated to be 129,000 acre-feet. Streams in the area are the principal means of ground-water discharge; the amount of discharge is essentially the same as recharge. The amount of groundwater used for municipal and rural water supply in 1975 is estimated to have been 5,000 acre-feet; a similar amount may have been used for industrial purposes. As a result of pumping, the potentiometric surface in 1975 had been lowered about 200 feet in the vicinity of Edmond and about 100 feet in the vicinity of Nichols Hills.
Chemical analyses of water from the aquifer indicates that hardness is greater in the upper part of the aquifer than in the lower part, and that sulfate, chloride, and dissolved solids increase with depth.
Reported yields of wells more than 250 feet deep range from 70 to 475 gallons per minute and average 240 gallons per minute. Potential well yields range from 225 gallons per minute when the fresh-water zone is 350 feet thick to about 550 gallons per minute where the fresh water zone is 850 feet thick. These estimates of potential yield are based on an available drawdown of half the thickness of the fresh-water zone and a specific capacity of 1.3 gallons per minute per foot.
Intrusion of saline water into the fresh-water zone is a potential threat to water quality in the aquifer if the pressure head in the fresh-water zone is reduced sufficiently to allow upconing of saline water. One way to avoid the problem of upconing is by steady pumping at low rates from widely spaced wells; however, information required to determine pumping rates and well spacing is not available.
For proper aquifer management the distribution of wells and rates of withdrawals should be designed to capture maximum recharge to the ground-water system. This may be accomplished by developing regional ground-water gradients that are sufficiently large to move water to pumpage centers but not so steep as to cause upconing of saline water or excessive water-level declines.