'It is amazing how much we don't know' about our water sources; House panel aims to fill in the blanks

Across most of Minnesota, the state lacks basic information to track underground pollution or to determine whether aquifers that supply drinking water can be replenished, state leaders say.

By David Shaffer, Star Tribune

Last update: September 19, 2007 - 12:05 AM

Across most of Minnesota, the state lacks basic information to track underground pollution or to determine whether aquifers that supply drinking water can be replenished, state leaders say.

"It is amazing how much we don't know," said Rep. Paul Gardner, DFL-Shoreview, who this week was appointed chairman of the newly created House subcommittee on drinking water source protection.

Gardner, whose district contains a former dump that is still polluting wells in North Oaks, said he plans to hold hearings on groundwater issues later this year and during the 2008 legislative session.

The lack of information about groundwater is acute in south-central and northern Minnesota, where detailed hydrological maps haven't been made, said Dale Setterholm, associate director of the state Geological Survey. The maps show how water moves underground.

In a three-part series that ended Tuesday, the Star Tribune reported that 20 significant areas of groundwater contamination lie beneath 35 metro communities. The combined polluted zones are 2½ times the area of Minneapolis. Much of the pollution is in suburbs where chemicals from old dumps seeped into groundwater.

Only the most populated areas around the Twin Cities have the detailed geological information helpful to regulators tracking pollution in groundwater.

Even before the newspaper report, Gardner said, House leaders had discussed appointing a committee to hold hearings on the problem.

He said every report on groundwater that he's read suggests that more data is needed to track contamination and aquifer depletion.

"We need to make sure what is in our water, what the emerging threats are and how much we can sustainably take out," Gardner said.

One of the most visible data shortages are the underground maps, known as geologic atlases, Gardner said.

Setterholm said the maps help regulators predict which direction a zone of pollution, known as a plume, is going. "It gives you a sense of whether that groundwater is going toward another water feature, whether it may be moving toward discharging into a lake, river or wetland," he said.

He said the Geological Survey, which began the mapping in 1982, has completed atlases for 17 percent of the state. Another quarter of the state has less-detailed assessments. He said cuts in the survey's budget has reduced the staff from 39 to 21 geologists, slowing the work.

Gardner said the committee also will examine whether Minnesota has a strategy for dealing with future demand for water and the possibility that new wells drilled near contaminated zones would draw pollutants toward them.

David Shaffer • 612-673-7090

David Shaffer • dshaffer@startribune.com

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