Groundwater Thresholds Project
Minnesota has abundant groundwater resources, but they are not unlimited.
The Groundwater Thresholds Project examines the effects of groundwater use on streams, lakes, and wetlands.
The project report includes recommendations for statutory definitions, as well as recommendations for thresholds for negative impacts to surface waters from groundwater use.
Report: Definitions and Thresholds for Negative Impacts to Surface Waters
- Minnesota is in the "urgency room" not the "emergency room" in terms of water use management.
- The state’s water management policies, statutes, and rules are strong and conceptually sound. However, the state’s water management statutes could be improved by clarifying terminology and better recognizing the interconnected nature of surface water and groundwater.
- There is a strong scientific basis for maintaining the natural dynamic patterns of surface water bodies by establishing protected flows for individual streams, protection elevations for individual basins, and target hydrographs for wetlands.
- Over the next five years, the DNR intends to set protected flows, protection elevations, and target hydrographs for water bodies in places where demand for water may be exceeding sustainable supplies. The changes to statute recommended in this report would help support that work.
- Add the following definitions to statute 103G:
- Negative impact to surface waters, in relation to water appropriations, is a change in hydrology sufficient to cause ecosystem harm or alter riparian uses long-term.
- Ecosystem harm, in relation to water appropriations, is a change in the biological community and ecology in a manner that results in a less desirable and degraded condition.
- Sustainable diversion limit, in relation to water appropriations, is a maximum amount of water that can be removed directly or indirectly from a surface water body in a defined geographic area on an annual basis without causing a negative impact to the surface water body.
- Combine many of the provisions in section 103G.285, which deals with surface water appropriations, and 103G.287, which deals with groundwater appropriations, into a single "Water Appropriations" section.
- A "threshold" is the point at which negative impacts occur. The report recommends the following approaches for determining thresholds for streams, lakes, and wetlands:
- Streams: we recommend a sustainable diversion limit of not more than 10% of the August median base flow of a stream in most circumstances, but recognize a diversion limit of up to 15% may be appropriate in some areas where water uses are less dependent on a consistent supply.
- Lakes: we recommend an approach that establishes sustainable diversion limits for two categories of lakes - lakes connected to stream systems that outflow much of the time, for which the diversion limit of the outflowing stream would be used, and lakes with infrequent surface outflow.
- Welands: begin testing the feasibility of establishing target hydrographs for various wetland types, with a focus on areas of the state experiencing heavy demand for groundwater.
A stakeholder advisory group provided input on the project and report. Advisory group members came from a range of organizations, including agricultural interests, environmental interests, businesses, community water suppliers and local government organizations. Technical teams were created to explore details related to streams, lakes and wetlands.
Presentations available as PDFs.
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