The most recent satellite data is showing a drop in Minnesota’s groundwater in recent years, and at least one scientist is suggesting that a main reason may be a change in when rain falls.

The National Oceanic and Atmospheric Administration’s Climate Watch magazine earlier this month showed what a pair of satellites measuring tiny changes in the earth’s gravity say about the nation’s groundwater levels, combining that with groundwater use. The headline was the very obvious drop between 2003 and 2012 in California, New Mexico, Texas and other parts of the South where drought has been persistent and pumping has been vigorous.

Brown areas show groundwater declines from 2003 to 2012. Blue areas show increases. Small circles show heavy pumping. Source: Climate.gov, National Oceanic and Atmospheric Administration.

But Minnesota stands out as well, not so much because of high pumping but because of a contrast with nearby regions in water drawdowns. Most northern tier states have experienced rising groundwater levels. (As we reported in our “Beneath the Surface” project, three quarters of Minnesota households get their water, not from rivers or lakes, but from wells that tap groundwater.)

Minnesotans have become more aware of pressures on the state’s groundwater availability and quality, but a problem is the difficulty in understanding what’s going on down where you can’t see anything. Satellite data is the newest tool to add to the measurement of water levels with monitoring wells, albeit not the most precise one. (One of the lead researchers analyzing the NASA data, Jay Famiglietti, was at the University of Minnesota in September as part of a Freshwater Society’s speaker series. )

For more on how the satellites, known as GRACE for Gravity Recovery and Climate Experiment, measure groundwater, see this.

So why would Minnesota see a decline in groundwater levels? One answer could be the increase in farm irrigation in parts of the state. In the sandy soils of west central Minnesota, farmers have increased their pumping substantially, and in two places the Minnesota Department of Natural Resources is trying a different approach to getting farmers, businesses and others to come to agreement on how much groundwater is used and who gets to use it.

But Don Rosenberry, a U.S. Geological Survey research hydrologist in Denver who studies Minnesota lakes, said scientists in his office have been looking at lower groundwater in wells in Cass County “and we’ve been wondering if it might be due to a change in the timing of rainfall.”

Minnesota rainfall — the source of recharging groundwater supplies — has been increasing over recent decades. But rain has increased, particularly in big storms, in the summer and decreased in spring and fall, Rosenberry said. “The big summer events rarely turn into groundwater recharge. . .So there might be a story here in addition to irrigation.”

It’s an idea he said the USGS looked at a few years ago and decided it needed more data or statistical power. It might be worth returning to the notion now, he said.

 

Jay Famiglietti

The traditional way of measuring groundwater levels is labor-intensive. You drill a bunch of wells in different locations, take measurements over time and combine the data to understand groundwater levels and flows.

The Minnesota Department of Natural Resources is working on mapping groundwater in the state, but there are still hundreds — if not thousands — of wells yet to be drilled. An understanding of groundwater quantity is crucial — three-quarters of Minnesotans get their drinking water from groundwater, and it’s also used to irrigate crops in parts of the state.

That’s what makes a special satellite used by a professor at the University of California, Irvine so exciting. Jay Famiglietti, also a senior water scientist at NASA’s Jet Propulsion Laboratory in Pasadena, is using the satellite to measure changes in mass on land. From those measurements, researchers can figure out how much water is there, he said.

“We can literally put together maps regionally and globally of the places that are gaining and losing water each month,” said Famiglietti, who will talk tonight about the research at a lecture sponsored by the Freshwater Society.

The satellite can zero in on an area the size of a large aquifer — about 60,000 square miles — but it can’t pinpoint areas as small as the three regions in Minnesota where DNR officials are looking at managing groundwater more closely. Famiglietti said using additional data can allow researchers to focus in on an area of about 20,000 square kilometers, and two other similar satellites to be launched in the future will likely be able to focus in on even smaller areas.

The satellite doesn’t tell researchers how much water is groundwater versus surface water, so the data must be combined with other measurements being taken on the ground, he said. Still, it offers the ability to measure water levels much faster than traditional methods, he said.

And because groundwater is such a critical part of our water supply, it’s important to be able to keep tabs on how much is there, he said.

“It hasn’t been well-measured or monitored. The general public is not even really aware of how important it is to our water supply,” Famiglietti said.

In addition to identifying shortages, the satellite data can help find areas that are prone to flooding. Famiglietti said the next step for researchers is to work with the state and regional agencies that manage water to incorporate the data into flood forecasts and regional drought monitors.

Daniel Roland/AP

Gov. Mark Dayton’s task force on broadband is recommending the state spend $200 million next year to develop greater access in areas that don’t meet state speed goals.

The money wouldn’t come close to building everything the state needs for universal access but would expand on the $20 million the Legislature approved this year for a handful of public-private partnerships to build needed access to homes, farms and businesses, task force chairwoman Margaret Anderson Kelliher said.

The state’s Office of Broadband expects to start taking applications for that money by the end of the month and to make project awards by the end of the year.

This year’s money should help pay for four to six projects that would show interest and need in rural Minnesota for better  service, state  Sen. Matt Schmit, DFL-Red Wing, said Thursday. Experience with those projects could help lawmakers decide on whether to expand funding next year,  he added.

Schmit and Kelliher spoke in Minneapolis at a broadband conference sponsored by the National Telecommunications and Information Administration that drew officials and telecommunications providers from a variety of states.

It is estimated that about 300,000 Minnesota households don’t have access to Internet speeds that they should to function well in today’s economy and that to supply access would cost between $900 million and $3 billion.

Rep. Ron Kresha, R-Little Falls, who helped foster Republican support for the money in the past session, told the conference he understood there are places where the private market alone will not provide what is needed.

In the hope of learning as much as possible from this year’s projects, Kresha said, “I’d rather see exemplary failures than mediocre successes.”