Central Sands Groundwater Workshop

Low lake levels and groundwater: background on the issues

This summer’s low water levels in some central and northern Wisconsin lakes have unleashed a flood of concerns from waterfront property owners. Low water levels have been particularly noticeable in the Central Sands area that includes Adams, Marquette, Portage, and Waushara counties.

This area represents a unique combination of geography and geology: very sandy soils, flat topography, and a lake-studded moraine that runs down the middle from Amherst to Oxford. Low water levels have been more common on landlocked lakes that are fed by groundwater or springs and that have no inlet or outlet streams. Water levels on such lakes fluctuate substantially from season-to-season and year-to-year, responding to the amount of precipitation to replenish the groundwater supply feeding the lake. There’s also evidence such lakes naturally fluctuate over decades, responding to larger weather patterns.

Recent dry summers and lack of winter precipitation are exacerbating these normal fluctuations. Many lakes here are currently experiencing low water levels due to persistent drought conditions in the area. “Preliminary information suggests water levels may be at 50-year-lows in certain lakes,” says Tim Asplund, the Department of Natural Resources’ state limnologist. However, global climate change and groundwater pumping near these lakes may be affecting them as well.

The Central Sands region also contains a high density of high capacity wells that supply water for many municipalities, individuals, and agricultural producers in the region. A high capacity well is one that singly, or together with other wells on the same property, withdraws more than 100,000 gallons of groundwater a day. This combination of geography, drought, and groundwater pumping has created a “perfect storm” for low water levels on the local lakes.

Water level fluctuations are normal for certain types of lakes, and efforts to do something about it may be ineffective. Yet there are some lakes where groundwater pumping at a regional scale is having an additional impact on lake levels that may be significant due to lake morphology, lake type, or geography. However, solutions are likely to be long term, regional, and institutional, rather than quick fix.

The state Groundwater Advisory Committee was created to make recommendations to the State Legislature on future groundwater management needs in Wisconsin. Members of the Groundwater Advisory Committee were appointed by the leaders of both houses of the legislature and the governor. They represent municipal, agricultural, environmental, and industrial interests. Two reports are due to the environmental and natural resources standing committees of the Legislature on Dec. 31, 2006 and Dec. 31, 2007.