The Ramsey County Beach on the north side of White Bear Lake will be closed this summer for the fourth year in a row. Yellow signs dot the beach, proclaiming: No Swimming Allowed. Beach Closed due to water level and drop offs.”
Near-record-low water levels in the lake have left so much of the beach high and dry that the edge of the water is only a short distance from an 8-foot drop-off into deep water. The low water has made the beach unsafe for children and inexperienced swimmers.
|Big stretches of White Bear Lake’s shallows are now dry.|
Elsewhere around the lake, especially on the north, northwest and south sides of the lake, grass and weeds grow on broad expanses of sand that a few years ago were covered with shallow water. Long boardwalks that once stretched to docks farther out in the lake now stop far short of the water’s edge.
“It’s very taxing and concerning for the people who have property on the lake,” said Mike Stawnychy, the chair of the White Bear Lake Conservation District. “It doesn’t look nice, it’s not appealing.”
Some people with lakefront or lake-access homes complain the low water has reduced their homes’ values, and low water at boat ramps has made it difficult for some boaters to use the lake, Stawnychy said.
“You get a good-sized family boat out there, and they have problems getting it in and out,” he said.
From mid-2003 to the present, White Bear’s water level dropped more than 5 feet.
In late 2010, concern about the drop among citizens and officials in communities around the lake led to a $200,000 research project conducted by the U.S. Geological Survey with assistance from the state Department of Natural Resources, the Pollution Control Agency, the Board of Water and Soil Resources and the Metropolitan Council.
The research, funded by the USGS, the state and a number of local governmental units, reinforced some old theories and produced some new evidence about the causes of the lake’s decline. The findings so far:
- White Bear drains a very small watershed and has always had big decreases in area and volume during extended dry periods when rainfall and melting snow do not keep up with evaporation.
- Chemical testing of water from wells around the lakes confirms that lake water is flowing out the bottom of the lake into groundwater aquifers that feed those wells.
- Pumping from high-capacity wells in suburban communities that mostly draw their water from those aquifers more than doubled over the last 30 years.
|Low water levels close the once-popular Ramsey County
Beach for a fourth year.
Statistical modeling suggests that the increased pumping is the biggest cause, by far, of the lake’s decline, according to Perry Jones, the USGS hydrologist who led the research. Other modeling predicts the lake will drop further if there is no significant and sustained increase in precipitation.
“When we did the models, we could explain much of the change due to pumping, less of the change to slightly lower precipitation,” Jones said.
In fact, precipitation – measured and recorded by weather observers near White Bear Lake – averaged only about a half-inch less per year in 2002-2011 than in the preceding decade.
A regression model simulated the impact on water levels of the precipitation decline and the increased pumping. The pumping accounted for nearly four and a half feet of the water level decline between 2003 and 2011, according to the simulation.
That four-and-a-half-foot difference across the lake equals a staggering 4.8 billion gallons – a loss of more than a quarter of the lake’s previous volume.
Not everyone buys the notion that groundwater pumping around the lake has had that big an impact. “I accept that the added pressure from that municipal pumping on that aquifer had an effect,” said Luke Michaud, the vice chair of the White Bear Lake Conservation District. “I’m skeptical of that four feet.”
White Bear Lake has always had big swings in its water level. In records going back more than a century, the record high level was 926.96 feet above sea level in May 1906. The record low, reached in November 2010, was 919.33 feet. The current level is up about a foot above that record.
In the late 1990s, hydrologists from the Minnesota Department of Natural Resources intensively studied the lake in research similar to the effort by Jones and USGS colleagues, including Jared Trost and Don Rosenberry.
Like the USGS work, the DNR research found a strong correlation between the lake’s highs and lows and the water levels in groundwater aquifers feeding wells around the lake. The DNR report theorized that over the long-term – years and decades – the biggest determinant of White Bear’s lake levels was the levels of water in multiple aquifers that both supply water to the lake and draw water from it.
Both the DNR hydrologists and Jones theorized that water flows from the lake into a sand and gravel aquifer and that – in some spots – the sand and gravel extend through a sandstone and shale barrier into a complex of two deeper aquifers, the Prairie du Chien, made up of porous limestone, and the Jordan, made up of sandstone.
Jones and the USGS team were able to take the research a step further and found solid evidence of the lake water’s flow into the Prairie du Chien and the Jordan, which the researchers treated as a single aquifer complex.
They tracked natural isotopes normally found in the rain falling on the lake, in the lake water and in the groundwater to water in nearby wells pumping from the Prairie du Chien-Jordan and the sand and gravel aquifer above it. Differences in the isotopes provided evidence that some lake water was migrating into the wells.
In another part of the USGS research, Jones checked DNR pumping totals for eight communities whose wells mostly pump from the Prairie du Chien-Jordan complex. Those communities are: Centerville, Hugo, Lino Lakes, Mahtomedi, North St. Paul, Vadnais Heights, White Bear Lake and White Bear Township.
The Prairie du Chien and Jordan water pumped from high-capacity wells operated by cities, golf courses and other big consumers of water use in those communities increased from 1.9 billion gallons per year in 1980 to 4.6 billion in 2007. In 2010, the most recent year included in Jones’ data, the total was 3.9 billion.
City water systems supplying growing populations were the biggest users of that water by far.
Dale Setterholm, associate director of the Minnesota Geological Survey, said that tracking of lake water into the Prairie du Chien-Jordan and then to wells around the lake provided strong evidence to support the theory that increased pumping in the eight communities lowered the Prairie du Chien-Jordan and that the lowering of the groundwater then caused the lake level to drop.”
In June 2010, a Metropolitan Council report discussed the “nearly insurmountable challenge of protecting the eleven-county metro’s 120,000 lakes, wetlands, streams and springs from degradation due to groundwater withdrawals…”
Now Jones and the USGS are working with state agencies to seek $536,000 from Minnesota’s Environment and Natural Trust Fund, money from the state lottery, to continue the research for three more years. The $536,000 would be matched by $336,000 from the USGS.
“It’s a lot of money,” Jones said, “but we’re proposing to do a lot of work.”
Jones wants to explore what the communities whose pumping is suspected of causing White Bear Lake’s decline might do differently to ease their impact on the lake.
Perhaps they could institute more-rigorous conservation programs, especially in the summer when lawn watering and other water uses peak. Perhaps they could pump from wells that would have less immediate impact on the Prairie du Chien-Jordan’s tendency to draw water out of the lake.
If the funding is approved by the 2013 Legislature, part of the study will attempt to measure how much lake water is ending up in municipal wells and explore the potential costs of additional treatment the communities might have to consider to protect their drinking water.
Jones also wants to expand the research to other lakes that are near White Bear, have similar geology and also have experienced declines in their levels. In a map that is part of his application for state funding, he identifies 10 small lakes that each lost 3 to 9 feet of water from 2003 to 2010. Otter Lake is on the Ramsey-Anoka County border. The other nine, all in Washington County, are: Oneka, Sunset, Long, South School Section, Round, Mann, Masterman, Olson and Jane.
And he wants to do seismic testing on White Bear Lake’s bottom to try to determine where lake water flows into the deeper aquifers.
Could that testing result in an effort to seal off the hole, or holes, in the lake bottom where the lake water flows into the Prairie du Chien-Jordan? It’s possible, but not likely, according to Jones. “I have a feeling, even if you seal it, there are probably other spaces where it’s leaking out,” he said.