PLANNING GROUND-WATER MANAGEMENT IN SOUTHEASTERN WISCONSIN

The seven counties of southeastern Wisconsin sit astride the subcontinental divide separating the Great Lakes and Mississippi watersheds. As a consequence, the population of the region relies on water from both Lake Michigan and ground water to supply their needs. Unmanaged historical reliance on a deep confined aquifer has produced unacceptable drawdowns and perhaps some related water quality problems. Water is being extracted from this aquifer at many times the rate of the natural replenishment, an unsustainable situation. Regional planners have spent the last three years assessing ways to manage the available supplies in a sustainable way and with minimized hydrologic impacts.

The process has examined alternative plans and has now converged on a final, preferred plan. Each has been assessed in terms of its effects on drawdowns, sustainability and impact on the baseflows of surface water bodies using a regional ground-water flow model. Examination of these effects shows the relative strengths and weaknesses of utilizing confined and unconfined aquifers, artificial recharge, recirculation of treated wastewater, and transfers of water across natural boundaries, including the subcontinental divide.

The final plan incorporates many of the strengths, but also lacks long-term vision in some aspects. An assessment of its regional effectiveness in terms of ground-water balances will be presented along with ramifications of the plan outside the region. Two problems stand out: the return of diverted Great Lakes water, and the absence of viable strategies for management in more rural areas.