Results of Barrington-area groundwater study revealed

When your own home is served by a private or municipal well, the security of that water source is hardly a dry topic.

Almost entirely dependent on their own underground water supply, the seven villages in the Barrington area were inspired by a rush of development in the late 1990s to study exactly how much stress that supply could withstand.

Now several years into that study, the Barrington Area Council of Governments is sharing what it's learned so far as it prepares to begin applying that information to policies on future development.

BACOG Executive Director Janet Agnoletti said the importance of the area's private and municipal wells is driven by the unlikelihood that Lake Michigan water will ever become a practical option.

While some of the legal restrictions for bringing Lake Michigan water so far west have eased in recent years, the necessary infrastructure remains prohibitively expensive, Agnoletti said.

"Water is becoming a significant question, and a significant issue, in Northeastern Illinois," she added.

In fact, 83 percent of the six-county region receives its water from Lake Michigan. Groundwater comes in second place at 15 percent. The final 2 percent comes from rivers.

Drawing on the expertise of hydrologist Kurt Thomsen, BACOG officials were most interested in determining how much water is available to their 80-square-mile area, how quickly that supply is recharged from surface water and how vulnerable it is to contamination.

Looking at historical data first, the study recognized one of the biggest changes in water levels came in the period from the mid-1960s to early '70s, when residential development was really taking off in the area, Agnoletti said.

Though the study itself provided snapshots of more recent years, an ongoing system of measurement is needed to determine how the water levels are adapting to changing circumstances, she said.

One of the most significant discoveries was that the western edge of the Barrington area - dominated by Barrington Hills - is the area where the underground aquifers are most quickly recharged by water from the surface.

The recharge rate is a function of ground conditions all the way from the surface to the aquifer itself. Thomsen said the amount of time it takes for a drop of surface water to reach an aquifer can vary from a few days to 500 years.

Also, only about 25 percent of water that lands on the surface ever makes its way to an aquifer at all, he added.

The more porous areas of land are not only most important to the recharge rate of the aquifers, but also the most vulnerable to contamination by spills on the surface.

The rate of contamination is also dependent on many factors, including how the particular contaminant behaves in water and different soil conditions, Thomsen said.

Agnoletti said she is already sharing the data with attorneys to see how it might be used in development policies and how binding and protective those policies might be.