Big and Little Blue Rivers

In the Upper Big Blue and Little Blue groundwater control areas, the predevelopment water levels used to develop the groundwaer change map are representative of the approximate mean water levels prior to 1950.  Irrigation wells are present in almost all parts of this control area where groundwater supplies are adequate and where development is not limited by other factors such as land use, soil type, or topography.   Groundwater withdrawals for irrigation during the past 42 years have caused water levels to decline 5 to 40 feet below predevelopment levels.  The main reason for the decline is the extremely high density of irrigation wells that occur in the area and the soil types do not promote deep percolation of irrigation water applied to crops.