Isanti County geologic atlas project underway

Jamie Schurbon, 

District Manager, Isanti Soil and Water Conservation Distric

A geologic atlas project is underway for Isanti County that will map the geology and aquifers below our feet in detail.

“Think of it as an MRI of the ground — a 3-D map that will assist in areas such as groundwater permitting and making water management decisions,” said Jamie Schurbon, Manager at the Isanti Soil and Water Conservation District (SWCD).

Groundwater declines have become a concern around the state, especially near the metro area, and having a geologic atlas available within the county is a way to determine groundwater levels. Therefore, Isanti County is joining the mix with several other metro counties where a geologic atlas is being or has been completed.

There are many uses for the geologic atlas. It will identify good locations for future wells, estimate the depth a well will need to be drilled, identify areas where groundwater is especially susceptible to pollution, determine flow directions of groundwater and inform management of pollutant plumes. Isanti County will be the last in the 11 county metro area to complete a geologic atlas, and its resulting maps can be interconnected with those already available to provide a regional map.

The poster child of groundwater decline concerns is White Bear Lake, where massive lake level reductions are thought to be at least partly due to the over-pumping of groundwater. The same is suspected, though less dramatic, in other north metro lakes. Some aquifers are declining and some cities, such as Ramsey, are struggling to find sufficient sources of water.

“While Isanti County is not currently experiencing dramatic ground water shortage problems, these are regional issues and we are not immune,” said Schurbon who also is a member of the Metropolitan (Met) Council’s Water Supply Advisory Committee. “It is widely accepted among Minnesota hydrologists that our current regional use of groundwater is not sustainable.”

According to the 2006 Isanti County Local Water Management Plan, water use in Isanti County is increasing.  While year-to-year use is variable, on average 500 million gallons were used in the early 1990s compared to around 700 million gallons in the early 2000s. The trend is for further increase as population and industry grows.

“There are many uses for the geologic atlas. It will identify good locations for future wells, estimate the depth a well will need to be drilled, identify areas where groundwater is especially susceptible to pollution, determine flow directions of groundwater and inform management of pollutant plumes. “

The most familiar use of ground water is for drinking and home consumption. In addition, irrigation is a considerable user. Agricultural irrigation is one form.

“In residential areas, lawn watering can also have a large impact on water levels,” said Schurbon who states that it is common for suburban Minnesota cities to see water consumption increase by over 30 percent in the summer months, largely due to lawn watering.

Economically, water availability is an important question. Certain industries need large water supplies.  Examples include certain food processing or manufacturing that uses water-cooled equipment. A geologic atlas helps these industries locate where water supply is sufficient to meet their need, and aids public officials in allowing appropriate, sustainable uses.

How much groundwater do we have compared to how much we are using? Surprisingly, the answer is largely unknown right now.

The Met Council uses computer models to map areas where potential groundwater problems may exist. Those maps currently do not extend into Isanti County, but the Anoka County maps are alarming. Nearly all of the northern third of Anoka County is forecast to have 1-3 foot drawdown of water table aquifers by 2030. By 2050 there are projections for 3-10 foot drawdown across large areas.

“Many of the sand plain wetlands and lakes are simply depressions where the water table is visible — draw down the water table and you draw down the wetland or lake,” Schurbon said.

Perhaps the issue of water drawdown will not be as large in Isanti County, where the widespread use of septic systems is a plus for groundwater recharge. Household water is treated and then returned back into the ground by the septic system drain field. But the same is true in northern Anoka County where they also have widespread use of septic systems but are now experiencing water drawdown issues.

The Isanti County Geologic Atlas project has received approval from the Isanti County Board of Commissioners.

“The Commissioners agreed that having a geologic atlas available for Isanti County will be a huge benefit in helping to know and understand groundwater quantity and quality in order to preserve and maintain one of our most precious natural resources — water,” said Kevin VanHooser, Isanti County Administrator.

“Isanti County currently enjoys a very abundant, clean and safe water supply and the more information there is available about the ground water here in Isanti County through efforts such as a geologic atlas the better off we will be,” said Lynda Woulfe, Cambridge City Administrator.

The actual work on the project will be a joint effort between Isanti County staff, city of Cambridge staff and the Isanti County Soil and Water Conservation District who is taking the lead and coordinating the project with staff from the offices of the Minnesota Geologic Survey and the Minnesota Department of Natural Resources (MN DNR).  The SWCD and City of Cambridge staff will be mapping the actual location of approximately 5,000 wells here in Isanti County. Isanti County is providing funding for the project as well as office space, computer equipment and staff time.

Each of the 5,000 wells, and many other Isanti County wells that have been previously mapped, contain a record of information for what the well driller encountered. That record of information will be used by both the MN Geological Survey and MN DNR staff to eventually create the Isanti County Geologic Atlas.

Funding for the MN Department of Natural Resources and the MN Geological Survey to complete Isanti County’s Geologic Atlas comes from the State’s Environment and Natural Resources Trust Fund (lottery proceeds). The financial contribution from Isanti County will be less than 5 percent of the estimated total project cost of $600,000. The Isanti County geologic atlas will be performed in phases, and will be fully complete in 4-5 years.

For more information about the geologic atlas project contact Jamie Schurbon of the Isanti SWCD Office at 763-689-3271 or visit the Isanti County SWCD website at www.isantiswcd.org and click on the “more info” reference under the geologic atlas section.

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