Little Rock Creek Sustainable Groundwater Use Planning Project Update

April 8, 2016 Project Update

A group of about two dozen residents of Morrison and Benton County met for the second time with staff from the Minnesota Department of Natural Resources to learn more about groundwater sustainability issues around the Little Rock Creek focus area and to offer feedback on how to address them.

The March 30 meeting of the Little Rock Creek Sustainable Groundwater Planning Project Advisory Team included presentations on:

• Why DNR is now focusing more attention on groundwater use in the Little Rock Creek watershed;
• What types of data are available regarding groundwater resources in the area, how it’s gathered, and how that data can inform decision making;
• How DNR is approaching concerns about groundwater use in the region.

Following the presentations, advisory team members and the roughly 15 people in the audience broke into small groups to discuss their reactions to the presentations, and then reconvened as one large group to share feedback.

What are the issues of concern?

Steve Colvin, deputy director of DNR’s Ecological and Water Resources division, explained that DNR has been reviewing groundwater usage across the state and has identified a number of areas where increased demands and other factors are giving rise to concerns. In the Little Rock Creek area, groundwater use grew by 180 percent between 1980 and 2015, compared to a statewide average increase of 32 percent. The density of groundwater appropriations also is increasing in a concentrated area around Little Rock Creek due to increased irrigation. Little Rock Creek relies on groundwater for much of its flow. The Minnesota Pollution Control Agency has identified Little Rock Creek as having impaired water quality, which may be made worse by reduced stream flows arising from groundwater appropriations. Calculations indicate that individual high capacity groundwater wells are drawing water away from Little Rock Creek. However, in order to get a more comprehensive assessment of groundwater use, a scientific model is being developed that evaluates all high capacity wells to determine if collectively there is a negative impact on the stream.

The importance of solid data

In order to better understand the relation between groundwater appropriations and Little Rock Creek, DNR is collecting and analyzing data that will help it create a scientific model that can be used in making future management decisions. Steve Thompson, who supervises DNR’s hydrogeology unit, explained that a variety of factors need to be considered in calculating sustainable levels of groundwater usage, including:

• The area’s geology (what types of soils, rocks, etc.);
• How streams and aquifers are connected;
• Whether shallow water table aquifers are connected with deeper buried aquifers;
• The amount of storage and the rate of flow of water in aquifers;
• The range in distance between where pumping occurs and where impacts are seen.

One technique used to learn more about such factors is to conduct an aquifer test, in which water is pumped from one well, while water levels in other nearby wells are observed to see if water levels fall and by how much. Several aquifer tests conducted in the area this past winter indicate that pumping from deep aquifers can affect water tables and Little Rock Creek, although there are significant differences in terms of impacts between different wells.

Greg Kruse, supervisor for DNR’s water monitoring and survey unit, described other types of data that the agency is gathering in the area. A network of observation wells and stream gauges equipped with data loggers provides detailed information about groundwater levels and surface water flows. All of the data will inform development of a scientific model that will allow DNR to more accurately determine the cumulative impacts of groundwater appropriations around Little Rock Creek.  The DNR is, focused on a half a dozen high-use areas around the state to better assess the effects of groundwater pumping on surface waters including Little Rock Creek.

How we plan to proceed

Dan Lais, a district manager for the DNR’s ecological and water resources division, said that DNR will consider past groundwater analyses, conduct additional groundwater flow analyses, and evaluate the cumulative effects from all users while allowing groundwater use in the interim. At the same time, a sustainable groundwater use plan will be developed to plan for DNR actions over the next 5 years in the Little Rock Creek area that will assure groundwater sustainability.  Grounded in scientific analysis of existing and new data, the plan will be informed by community input and state laws, which have been revised by the legislature in recent years to require closer attention to the relation between groundwater pumping and impacts to surface waters. In order to protect rivers, lakes and wetlands, DNR will need to determine how much groundwater can be pumped before negative impacts occur.  If negative impacts have occurred, the DNR will work with appropriators to keep water use below that threshold.

Feedback

After breaking into small groups to discuss reactions to the preceding presentations, members of the project advisory team and audience participants shared feedback with the whole group. Among the comments:

• More data is needed over a longer period to establish baseline conditions.
• The time frame for developing a groundwater management plan is too short.
• The connection between shallow and deep aquifers identified in recent aquifer tests is new information that is critical to understanding the area’s groundwater resources.
• The details of the groundwater modeling that will be done may be of less concern than how the model is used to make management decisions.
• Economic considerations should be taken into account when the plan is developed.
• Some participants expressed skepticism regarding the DNR’s role in all aspects of creating the plan, and whether the real issue at stake is the quantity of groundwater available of the status of Little Rock Creek as a trout stream.

Next steps

The technical team working on compiling data and creating the scientific model to be used in making groundwater management decisions was scheduled to meet in Rice City Hall from 10 a.m. to 12:30 p.m. on Thursday, April 7. The meeting was open to the public.

The next meeting of the project advisory team is scheduled for Wednesday, April 13, from 1 to 4 p.m. at the Rice City Hall. At that meeting, DNR will review the results of the recent aquifer testing, describe the scientific model in more detail, and discuss the content of the Little Rock Creek Area Sustainable Groundwater Use Plan. 

Contact Information

Direct questions about this project can be addressed to Mark Hauck, DNR project manager, at 320-223-7846 or mark.hauck@state.mn.us .

To sign up for email updates and follow progress of the plan on the DNR’s project web page go to: http://www.dnr.state.mn.us/waters/groundwater_section/sustainability/lrc/index.html .

For more information on groundwater management, visit www.mndnr.gov/gwmp/index.html.