| Like a bank account, storage allows withdrawals to be made
without depleting the account.
As shown in this figure, the two most important factors influencing storage in the southern valley aquifer are recharge (from the Bannock Range and to a lesser extent from the Portneuf Gap) and pumping (primarily from municipal supply wells).
The graph shows water levels measured in two wells and the monthly amount of water pumped from municipal wells in the southern aquifer. The graph spans two very different pumping periods: a cool, wet, summer in 1993 and a dry summer in 1994. Note how drastically the pumping rate differed between these two periods.
In particular, the graph clearly shows how drastically water level (and hence storage) declined when pumping rates increased in the dry summer of 1994.