Study to provide picture of region’s groundwater

Private well owners will play key role

High-tech meets history this March. That’s when water professionals will employ global positioning equipment to record precise locations and elevations – and use manual probes to measure water levels – at hundreds of wells in the seven-county metropolitan region.

Map of Twin Cities aquifers and link to larger pdf map

The region’s most productive aquifer is the Prairie du Chien Jordan. An estimated 30% of the region’s population growth by 2030 will occur outside the reach of that aquifer. See larger map (pdf).

Their work is part of a “synoptic study,” an effort to capture water-level data from over 300 wells in a very short time. The study will aid the Metropolitan Council’s groundwater modeling efforts and help to determine the best ways to sustainably manage the region’s water supplies.

Water-level measurements are critical for calibrating groundwater models, and for determining whether lakes and rivers gain water from groundwater or lose water to groundwater, said Mindy Erickson, Ph.D., a Minnesota Pollution Control Agency (MPCA) research scientist.

Private wells play critical role in study

The 2008 aquifer study will rely heavily on data collected from private wells, which far outnumber public wells in the region, said Lanya Ross, senior environmental scientist for the Council. “Residential wells seldom pump enough water to change the level in an aquifer,” she explained, “so they provide the best overall picture of water levels.” Owners’ anecdotes also help researchers understand how an aquifer behaves over time, she said.

Data collection will span just a few days. Measurements will take place in March and August to provide “snapshots in time” for both winter and summer conditions, Ross said. The ambitious project will examine the region’s three primary groundwater supply aquifers: the Prairie-du-Chien-Jordan, Franconia-Ironton-Galesville and Mt Simon-Hinckley. The study is jointly funded by the Council, the United States Geological Survey Water Science Center in Minnesota, the Minnesota Department of Natural Resources (DNR) and the MPCA.

Aquifer data will have a wealth of uses

Data will help researchers understand impacts from changes in climate patterns, water demand and historical water management practices, said Jan Falteisek, a supervisor in the DNR Waters Division. Falteisek said comparing the data with measurements gathered as early as the 1880s will help agencies determine the size of regional pumping centers, the direction of groundwater flows and historical trends for each aquifer.

“The study will also help MPCA further understand how contaminants travel through groundwater,” Erickson said, “and how to more effectively protect and improve water quality.”

Study goals also include determining how water levels:

Vary because of seasonal demand
Change as a result of human water use
Impact streams and lakes

“This is an important study,” Falteisek said. “These periodic area-wide measurements provide an update on the state of the groundwater system. The data collected will be used to evaluate the current resource and to help us understand groundwater system changes over the past 50 to 100 years. That knowledge can then point both water users and managers to a future that will benefit everyone."

Regional water levels were last measured in 1995. The Council estimates that the population served by the aquifers has grown by about 500,000 people since then, primarily in outer-ring suburbs that rely exclusively on groundwater.

Study results and the regional groundwater model will inform the Council and Metropolitan Area Water Supply Advisory Committee in developing recommendations for regional water supply management.

To learn more about the study, contact Lanya Ross at 651-602-1803 or lanya.ross@metc.state.mn.us.