See the table below which provides a summary of the distribution of irrigated and non-irrigated acres for HUCs in Idaho. Teton, Raft, Portneuf, and Blackfoot are those HUCs which contain significant non-irrigated lands with potential for conversion to irrigation. Of the eight HUCs with the largest irrigated acreage, seven are located primarily on the Snake River Plain, see figure below. A summary of the information obtained from these wells is published by the U.S. Geological Survey in cooperation with the State of Idaho and other agencies in their annual report entitled Water Resources Data-Idaho. The majority of wells are located within those regions where competition for water has been more intense, such as the Eastern Snake River Plain.
Most wells show annual fluctuations of less than ten feet.
Notable exceptions include wells in Bruneau, Willow, and Teton where annual fluctuations can vary to a maximum of 50 to 65 feet . The figures below summarize the water table data. The first figure list locations of wells used to illustrate changes in ground water levels. The second figure illustrates the fluctuations in the water table over time. Most tributary streams are considered to be at least somewhat hydraulically interconnected with the aquifer, changes in stream flow can affect the amount of water available for aquifer recharge.