New research from the U.S. Geological Survey shows White Bear Lake water levels are falling because communities north of the lake are pumping too much water from an aquifer connected to the big lake.
The water level at White Bear Lake has dropped five feet in the last decade. Dry weather accounts for just a small part of the drop, said USGS hydrologist Perry Jones.
Jones said growth in suburbs north of the lake has led to greater demand on the Prairie du Chien-Jordan aquifer.
When the aquifer depletes, lakewater trickles from higher elevation to replenish it.
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"There was probably always some water from White Bear Lake leaving and going down into the lower aquifers," Jones said. "But what's happened is that by increasing the amount of pumping, you actually lower the water levels in that lower aquifer, so it exacerbates the amount of water leaving the lake."
More precipitation could replenish White Bear Lake, Jones said, but it will take more rain and snow to make up for what has been lost.
"We're getting a better understanding of the fact that lake and ground waters are a tide system. And so that you pull groundwater out, that can result in a loss of water from the lakes," Jones said. "There's a direct connection often between lakes and the local aquifers that needs to be recognized."
Jones says communities that draw water from the aquifer should monitor their usage carefully and develop a better management plan.