Use of thermometry in hydrogeologic studies of glacial deposits at Worthington, Minnesota

Precise measurements of fluctuations of ground-water temperature based on monthly readings in shallow glacial-outwash aquifers may be used to study ground-water movement and recharge. An increase in storage in the shallow basin of Okabena Lake, Worthington, Minnesota, permits the water to cover a much larger area and probably increases the opportunity for infiltration of lake water into aquifers connected with the lake. In a shallow artesian aquifer confined by relatively impervious glacial till, water moves toward the land surface in response to steep temperature gradients in the winter, and cool water descends to the aquifer when the upward temperature gradient is lowered or eliminated. Thermometry may also be used in hydrogeologic studies of limestone terrane.