Analyzing the sustainability of groundwater pumping in the Fryeburg sand and gravel aquifer

Presentation (pdf document)

Charlie Fitts, University of Southern Maine Geosciences Dept., Gorham, ME, 207/780-5351, cfitts@usm.maine.edu

The Fryeburg aquifer has seen significant recent increases in groundwater pumping to provide bottled spring water in addition to the town’s water supply. The present discharges are sustainable in a purely physical sense, in that pumping does not exceed aquifer recharge. A more relevant concept of sustainability examines these key manifestations of pumping, to determine if they are acceptable:

• Drawdown of the water table
• Reductions in groundwater discharges to surface waters
• The zones of contribution to the wells, which may need land use restrictions

Three-dimensional models of groundwater flow in the aquifer have been developed and used to quantify these under past, present, and future pumping scenarios. These analyses provide at least some of the basis for determining sustainable levels of pumping. In addition, there needs to be an understanding of the surface water ecosystems and how they respond to reduced flows. The results indicate that the currently-permitted levels of pumping significantly diminish flows in the brook that runs through the center of the aquifer. The impacts are especially significant during late summer, when water levels are low and bottled water pumping is high. The modeling process helps point out the greatest sources of uncertainty in our understanding, and guides future data collection.