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. The quality of ground water in Butte Valley is generally suitable for most uses. Dissolved-solids concentrations in the water rarely exceed 500 milligrams per liter. However, owners of a few wells completed in the volcanic rocks report that the water has a sulfur odor, and sodium concentrations exceed 50 milligrams per liter in water from a few wells completed in these rocks. Shallow wells completed in the lake deposits about 4 miles southwest of Dorris produce highly mineralized water that exceeds 500 milligrams per liter dissolved-solids concentrations probably because the water that recharges the aquifer in that area becomes mineralized while percolating through the overlying playa deposits.