How do we define lake health? How do we measure it? What information helps us be better stewards of our lakes? There aren't simple answers to these tough questions, but the information in the WHAF for Lakes application is designed to help us work together on issues that impact lake health.

What is a healthy lake?

A healthy lake is one that is nearest to its natural state. It is free from our pollution and has a natural shoreline that protects the bank and filters runoff. It is surrounded by a landscape that delivers water and energy consistent with its self-sustaining plant and animal communities. 

A healthy lake can withstand changing conditions and seasonal fluctuations. Most importantly, it has a human community and society that values these resources and invests in the protection and restoration of the water, watershed, and interacting and dependent communities.

When is a lake unhealthy?

An unhealthy lake has received more disturbance than it can handle, forcing it to deviate from its natural state. The lake is out of balance with the water and nutrients and the fish and plant communities are impacted. A degraded lake is less resilient and may decline further under changing conditions.

Restoring a degraded lake back to a healthy condition is usually a lengthy, expensive, and complex challenge. In contrast, protecting a healthy lake and the surrounding land helps ensure that the ecological and economic benefits that it currently provides are more resilient and likely to be sustained into the future.

What does the lake 'health score' mean?

The Lake Health Score is a starting point, a comparison that helps you see the range of lake conditions across Minnesota.

Each overall health score combines three sub-scores. These are designed to encourage investigation into what might be influencing the lake ecosystem. The lake health scores reflect both measured conditions in the lake and the level of risk from land use activities in the lakeshed.

We also know that expectations for a shallow wetland lake are much different than a deep, cold northern lake. To provide a meaningful comparison, lake health scores are calculated based on expectations for lakes of the same type.  

Steps for Exploring Lake Health

Almost 3,000 lakes in Minnesota have been given health scores. The overall score can help you compare a lake of interest to other lakes across the state, or to other lakes nearby. In the example below, the Chippewa River major watershed is being highlighted. The lakes within that watershed range from a low score of 20 to a high score of 80; on a 0-100 scale. 

Open the WHAF for Lakes application

Step 1: Click on the map to set a location.

Step 2: Review the list of lakes within the area you selected.

Step 3: Click on a lake name to review health score details on the summary page. 

Step 4: Use the Map to explore your lake's watershed, or lakeshed shown with a dotted line.

Step 5: Click the tabs across the top for more detail about your lake.

• The overall health score combines scores for water quality, biology and hydrology. 
• Click on the 'Learn More' buttons to understand the scoring approach.
• Click on the Stewardship tab for information and ideas for managing your lake. 

By sharing the data and scoring our lakes, we are taking a step toward a more holistic understanding these interesting systems.  The next step is to discuss how this information can help us be better stewards of our important and iconic Minnesota lakes.

How is lake health related to watershed health?

A lake's watershed (or lakeshed) is all land and surface water features upstream of a lake outlet that contribute water to that lake. Lake health is influenced by the landscape characteristics and land uses within their respective lakeshed.

Most of our landscapes and surface waters have been altered to accommodate agriculture, forestry, transportation, industrial, and urban uses. Some land uses also introduce contaminants that further impact the health of our lakes.

The health of each lake reflects the intensity of landscape alteration and internal factors such as lake area, depth, and diversity of nearshore habitat, as well as external factors such as soils in the lakeshed, land use, altered hydrology, lakeshed to lake size ratio, groundwater inflow, and the source and amount of surface water inflow.

It is the unique combination of these influences that determine the quality of the water and the health of the aquatic community in a particular lake. The characteristics of each lakeshed help us to evaluate conditions that may improve or degrade lake health into the future. For example, indicators that show whether water entering a lake is dominated by groundwater or by surface water can help focus management efforts on the most influential factors.

The new WHAF for Lakes application can help us learn more about the connections between lake health and lakeshed conditions. 

Partners Make it Happen

The WHAF team would like to acknowledge the partners that helped us design and deliver the WHAF for Lakes. Thanks for your expertise and assistance!

DNR Ecological and Water Resources; Lake Ecology Unit: 

• Paul Radomski, Unit Research Scientist
• Kristin Carlson, Decision Support Specialist
• Steve Kloiber, Unit Supervisor

University of Minnesota, Remote Sensing Laboratory: 

• Leif Olmanson, Research Associate