Recharge!

Remember our policy focus at the legislative session? We worked hard to pass a  groundwater recharge study (HF 1141/SF 1643 (Rep. Sandell/Sen. Weber) and we succeeded! Work started quickly on July 1 as Freshwater assembled a team to begin the 18-month study. It will focus on parts of the state that may need to recharge aquifers to meet the water needs of growing communities, manage demands of competing uses, and protect natural systems. Evaluating the economics, policy, engineering, and hydrogeologic considerations now will allow us to consider enhanced aquifer recharge when, where and if it is needed.

Changes in groundwater dependence, the magnitudes of expected change in the seasonality and intensity of precipitation, evapotranspiration, and altered hydrology are key factors that impact future recharge of aquifers. The study team will draw on successful examples of recharge that are already being done in the upper Midwest. These will be translated to the specific geologic, economic, and engineering conditions present in four study areas in Minnesota. We will evaluate water sources like treated surface water or wastewater for their potential to recharge groundwater. Energy use and infrastructure costs are also part of the equation and the least easily understood.

To deploy recharge as a tool some policy changes are important. For one, the Groundwater Protection Act of 1989 has an anti-degradation clause that is interpreted by some to prohibit groundwater recharge. Also, the EPA ultimately grants authority for wells that inject water (except to sovereign nations like the Shakopee Mdewakanton Sioux). These and other policy barriers need to be evaluated before aquifer recharge can be deployed broadly although locally some communities like Albertville-Hanover-St. Michael have already found aquifer recharge to be the solution to their water needs.

Orange area represents Buffalo Aquifer (Fargo-Moorhead), green is Straight River Groundwater Management Area, red is Southern Washington County, and blue is Rochester Area. Graphic by Brain Bohman

We will study four areas that have different motivations for recharge:

1) Fargo-Moorhead relies on a small buried glacial aquifer that isn’t easily recharged and doesn’t have a lot of capacity. It may limit development of the region. Moorhead also has an annual flooding problem and we will ask whether recharge can siphon off some of the flood waters.

2) The Straight River Groundwater Management area near Park Rapids. This sandy area is intensively irrigated cropland and seasonal lows in the water table aquifer have the potential to have a thermal impact on a coldwater stream. The city of Park Rapids has also had problems with nitrate in shallow groundwater. We’ll study whether water is available at the right time of year to offset drawdown and if it can dilute nitrate contamination and keep the stream cool.

3) Southern Washington County has a similar problem of aquifer depletion impacting a coldwater stream but in this case is a bedrock aquifer. Located in a growing metropolitan area, the current use may not be sustainable. The migration of 3M legacy contaminants (PFOS, PFOA) into parts of the aquifer used for a municipal supply well is a long-term problem in search of a solution. Recharging aquifers with clean water may provide relief for both of these future scenarios.

4) Greater Rochester is planning for a doubling of population due to expansion of the medical campus.  Our question: Will their bedrock aquifer be adequate and remain free of contamination or will groundwater quantity and quality limit their ability to expand?

In addition to experts across science, engineering, economics, and policy disciplines, Freshwater is engaging experts and stakeholders in these regions as part of the process.  A project report will be delivered to the 2021 legislature.

— Carrie Jennings, research and policy director

2 thoughts on “Recharge!”

  1. Does the irrigation of potatoe fields above the Straight River aquifer drawdown the aquifer enough to affect nearby lakes? Cotton Lake east of Detroit Lakes has no source of water other than groundwater. It may be spring fed from below the lake bed. In the past several years the lake level has been steadily declining; declining as much as two feet of lake level since we built our cabin on the south shore 15 years ago. Is this attributable to a decline in the water table (the aquifer) or to drier weather over the last 10 years or so? Thank you.

  2. Hi Leo, Thanks for your comment! Here is a reply from Carrie Jennings, our research and policy director:

    We are investigating the use of groundwater for irrigation in the Straight River watershed and how it affects the river, primarily. Lowering of the water table would also affect lakes. However Cotton Lake is not in this watershed; it is in the Ottertail River watershed. https://mrbdc.mnsu.edu/mnnutrients/watersheds/otter-tail-river-watershed. This part of the state has not been as wet as other areas; precipitation is normal to slightly below normal and although streamflow is high, wells in nearby watersheds are in decline. https://files.dnr.state.mn.us/natural_resources/climate/current_conditions/hydrologic_conditions_august_2019.pdf
    Thanks for the heads up; this is the part of the state, the prairie-forest border, that is likely to see changes first. We know it has in the past.

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