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[7 4 UNIVERSITY OF MINNESOTA TWIN CITIES September 15, 1986 Jeanne A. Mabusth Zoning Administrator City of Orono P.O. Box 66 Crystal Bay, MN 55323 Dear Jeannet Gray Freshwater Biological Institute College of Biological Sciences P O Box 100 County Roads 15 anu 19 Navarre. Minnesota 55392 (612) 471-8476 In the letter to you from Mr. John Noble concerning the use of water permit 86-6178 it is stated that 152,500,000 gallons are pumped daily from the Prairie du Chien aquifer. This amount is said to be 7,500 times more water than will. be used by the Ulrich residence. This assumes an average daily use of 20,300 gallons by the residence. If proven to be economical, it is not unreasonable to assume that 7,500 such systems would be installed and the aquifer water use would be doubled. They seem to have made the best case against this use of groundwater. The evidence I have seen indicates that the aquifer is presently being drawn dowr-. It is clear that water in most midwestern aquifers is not recharged as fast as it is used. I know of no evidence that removal of water from the aquifer and discharge into Lake Minnetonka results in recharge of the aquifer because of perfect exchange between the lake and the aquife-. If this were `rue, Minnehaha Creek would be dry, These lakes are not the majt. .;ource of rechu rge. There are many issues to be addressed before I would be supportive of the use of heat stored in groundwater for heating. If discharge was not directly into the lake, w`1at protections against erosion and nutrient loading would be required? There are many potential negative imparts that cannot address without more information. One can alter water migration by large scale p-.mr,ing. what impacts will this have on water availability and quality? Let me put the effects of groundwater depletion in the simplest terms possible. Two thirds or more of the freshwater in the continental U.S. has been ground- water. It Is used for agricultural, industrial and domestic purposes. use ine- vitably causes contamination. It is estimated that groundwater will be substantially depleted in 40-50 years. That will ]pave us with the remaining one '.`:rd of surface water that will be used three tames as much as at present. We can anti(71pate severe contamination if standards are not improved. we will face greatly increased costs for recovering the water in a �leen form.