What Makes a Healthy Lake

Measuring Lake Health

There are three primary measures that are used to determine how healthy a lake is. They include water quality, fish habitat, and biodiversity. All of these are interconnected in that water quality affects fish habitat, which affects biodiversity, and so on.

Water Quality

Water quality refers mainly to the abiotic or “non-living” aspects of the water itself. It includes things like:

  • Dissolved Oxygen
  • Temperature
  • Phosphorous
  • Total Dissolved Solids
  • Total Suspended Solids
  • Bacteria counts
Fish Habitat

Fish habitat refers to the biotic or “living” and abiotic factors of the water that provide suitable habitat for fish specifically. It is measured through things like:

  • Thermoclines, which are areas in which the water temperature drops but dissolved oxygen is still prevalent enough to support life
  • Creel surveys and other fish counts, including angler diaries that help determine the health of populations
  • Spawning and nursery habitat assessments

Biodiversity measures the variety of life present within the lake. It includes:

  • The types of plants and/or animals present
  • Richness or amount of plant/animal life

Learn more about the importance of protecting biodiversity and the impact of community-led science programming through the video to the right!

Threats to Lakes

Unfortunately, human activity both on the water and on the land is negatively impacting the health and integrity of our lakes. Below are just a few of the ways that the things we do can negatively impact our lakes.

Land-related Impacts

Runoff from pollutants like insecticides, road salts, and other pollutants has the potential to contaminate our lakes and also reduce zooplankton that feed fish and consume algae. These issues create problems for wildlife and for humans given that our lakes are a major source of drinking water!

Learn more through the below video!

Runoff from fertilizers and septics can overload our lakes with nutrients. These nutrients "feed" algae, promoting its excessive growth and resulting in a reduction in oxygen in the lake. This excessive growth is called an algal bloom, and it is a large issue for aquatic wildlife and humans too! 

Learn more through the below video!

Removing native plants from the shoreland, or even going so far as to harden shorelines with walls and retainers, removes important habitats, posing a major threat to biodiversity, and also compromises water quality.

Learn more about other human-driven impacts on biodiversity through the below video!

Water-related impacts

By far, recreational boating and commercial shipping are the most impactful human-related activities affecting the health and integrity of our lakes. Boating can pollute our water and create waves as well as change the water’s temperature, which can impact fish and wildlife. Additionally, boats, if improperly cleaned and especially when travelling from lake to lake, can introduce invasive species to new areas, which outcompete native species for resources.

We have an opportunity to reduce our impact both on land and in our waters to support the health and integrity of our lakes. Through the Blue Lakes Program, you can take an active role in protecting your lake and reducing your impact on our water!

Scroll to Top