Thus, the maximum amount of ground water available in the valley for annual use is approximately 102,000 acre-feet. Most of the land available for future development is in the northern end of the valley where surface soils and subsoils consist of fine-grained lake deposits that do not allow irrigation return flow to reach the aquifer. Therefore, unless surface water is imported to augment natural recharge, the amount of water available for agriculture appears to be much less than the projected demand. Water levels might fluctuate as a result of annual precipitation and withdrawal cycles but are essentially unchanged in the long term. However, because of the limited storage capacity of the Butte Valley Basalt and the large volume of withdrawals from that formation, water-level decline is sufficient to cause some wells to go dry during the withdrawal season.
Water levels recover, however, when withdrawals cease after the growing season.
Deepening wells so that they penetrate the underlying sand and gravel of the lake deposits or the volcanic rocks could alleviate this seasonal situation.