Approximately 30 percent of the average annual precipitation occurs in rainfall events ranging from a trace to a half inch, which provide limited benefit for crop production. About 60 percent occurs in events ranging from one half inch to 2 inches, with the remaining 10 percent occurring in larger events. Rainfall events exceeding one half inch in the area are generally short duration, high intensity events which exceed the infiltration rates of the soil. Consequently, runoff occurs if the land is not prepared to hold the water in place until it has time to soak into the soil. This is especially important when large precipitation events occur in the area.
Droughts occur and reoccur in the area, as do cycles of above average precipitation.
Each of the principal crops grown in the Water District require specific amounts of water measured in inches to grow the plant and produce a specific yield. For instance, five inches of water is required to grow the cotton plant. Then, for every additional inch of water the plant receives in a timely fashion, it will generally produce about 50 pounds of lint cotton. The same type of equations are available for all other types of crops grown in the service area of the High Plains Underground Water Conservation District. Therefore, depending on the market price he expects to receive for the crop he is growing, he sets a minimum yield he must produce to break even, to make a 5 percent profit, and to make a 10 percent profit on his investment.