The Minnesota Department of Natural Resources says a new study of groundwater use and White Bear Lake shows residential irrigation and other groundwater uses have minimal impact on the lake level in the long term.
The DNR released its findings on Wednesday, as the Minnesota Court of Appeals weighs a years-long lawsuit by White Bear Lake residents.
Previously, homeowners sued and won, saying the agency wasn't doing enough to keep groundwater pumping from contributing to precipitous drops in the lake's water level.
Ramsey County District Court Judge Margaret Marrinan ruled last year the DNR had to take steps to cut groundwater use, better police permitted wells and come up with alternate sources of municipal water to keep the lake from dropping precipitously, as it has in recent years.
In releasing its new groundwater study, the DNR acknowledged that wells in the region do have an impact on lake levels. But the agency said the study indicates other factors, like rainfall, evaporation and other weather phenomenon are also significant factors.
"Groundwater use from existing permits does contribute, its not the sole cause, but it does contribute to the lake falling below its protective elevation on occasion," said Barb Naramore, assistant DNR commissioner. "That's not a violation of the sustainability standard, but is something that is of interest and concern to the department, and something we will be working with those permit holders to evaluate ways we may be able to address."
Naramore estimated the effect at a maximum of about three feet. White Bear Lake's surface level has varied by nearly six feet, including an all-time low about five years ago.
But the study found one of the most controversial elements of the court decision last year, a proposed residential watering ban when the lake reached a given level, "would not have a significant effect on water levels in White Bear Lake."
That finding parallels the DNR's legal argument, which was bolstered by the Legislature. Lawmakers put a temporary moratorium on the irrigation ban this spring, as the law suit winds its way through the state's appeals system.
Naramore defended the findings — which weren't part of the years-long trial and won't be a factor in the agency's appeal of the court ruling.
"Folks may think we have a motivation behind our analysis," Naramore said. "We do not. We have the very best groundwater modeling talent working on this. We feel very confident about the conclusions we've reached."
The DNR does have a "protective elevation" set, at 922 feet above sea level, for White Bear Lake, and Naramore said the agency does have an interest in maintaining water quality and keeping the lake suitable for recreational uses. But she also says at least some of the variation in the levels that have alarmed residents and boaters is also beneficial to the lake's ecosystem in the long term.