PROBLEMS FROM DEVELOPMENT 73 



in about 40 per cent of the valley area, and the water in 

 these aquifers is probably confined under impermeable 

 materials in a sizable but unmapped additional area. These 

 aquifers are not replenished naturally by downward perco- 

 lation in the areas where the confining layer is present, but 

 receive inflow from recharge areas that may be many miles 

 away. Some difficulties are encountered in trying to abide 

 by nature's method of replenishment. It is probable that 

 the bulk of all recharge, including that to the artesian 

 aquifers under the floor of the valley, comes from the al- 

 luvial fans of the tributary streams. The water in these 

 permeable materials is readily replenished from the streams 

 and from gravity diversions and irrigation. The problems of 

 greatest overdraft are in the areas between the major tribu- 

 taries and beyond the coarse deposits of their fans; they are 

 probably due in part to the slow rates of underground 

 movement from the stream to the area where the water is 

 pumped. 



In order to achieve effective ground-water storage of the 

 imported water, it may be necessary to develop techniques 

 that will by-pass the natural paths of slow replenishment 

 and recharge the reservoir directly in the area of use. This 

 was the basis of a successful experiment in artificial recharge 

 through wells in the Lindsay-Strathmore Irrigation Dis- 

 trict in the first four months of 1932. The district is 10 to 18 

 miles south of the Kaweah River, and water has been 

 pumped at rates that have lowered the water levels 2 to 5 

 feet per year. The district also uses water from 40 wells 

 along the watercourse of the Kaweah River, where the al- 

 luvium is readily recharged during flood flows. Prior to the 

 1932 irrigation season, water from the watercourse was 

 pumped into the district's flume, screened, chlorinated, and 

 introduced into 75 per cent of the irrigation wells within 

 the district. The wells absorbed water generally in propor- 

 tion to their yield when pumped, and water levels in the 

 reservoir rose as much as 50 feet in some places. No cases of 



