Lakes are receiving bodies; what we do on the land, effects the state of the lake. Lake health is measured in three main areas: water quality; fish habitat; and biodiversity. However, each of these areas of focus are interconnected. Water qualify affects fish habitat as does biodiversity etc.
Water quality parameters include Dissolved Oxygen, Temperature, Phosphorous, Total Dissolved Solids, Total Suspended Solids (measured through Secchi Disks), and also notable are bacteria counts. Water quality is also indicated through benthic invertebrate sampling.
Fish habitat is a monitored through thermoclines (the areas in which the water temperature drops and yet the Dissolved Oxygen is sufficient to support fish), and through Creel Surveys, other fish counts, including angler diaries. However, fish habitat is also affected and measured through an assessment of spawning and nursery habitats.
Biodiversity, especially at the shore, affects both fish habitat and water quality. The types of plants, the richness or amount of plant life, in turn provides shelter, shade, and also habitat for zooplankton and other species that supports fish and wildlife. However, plants also filter and clean water.
Therefore, human activities on the land, mainly removing the base of the food web/removing native plants and hardening surfaces reduces biodiversity, increases runoff and removes filtration- especially around shorelands. Shorelands, specifically the upland and riparian zones at 30 metres to the high water mark, account for 75% of all the functions (water filtration, nursery and wildlife habitat, erosion control etc.) in a lake basin. Other activities that produce inputs/pollution, such as farming and industry also affect lake health.
Human activities, in the lake basin, can also affect lake health. Boating (especially inboard motors) can churn up substrate and create waves introducing additional phosphorous sources to the lake, and supporting algal growth. Boating can also mix warm waters lower into the water column reducing fish habitat. Draw downs (through dam-controlled lakes) can affect biodiversity and habitats for fish, turtles, and other wildlife. Direct persecution of turtles can remove important water "cleaners" and reduce the dispersal of seeds, in turn limiting biodiversity.
Below is a list of educational resources on the factors that harm or help the health of a lake.
Five Human Impacts on the Environment (video, 10 min.)
This video discusses everyday human activities that are driving species to extinction and the importance of biodiversity.
Different Forms of Pollution and Their Ecological Effects (video, 9 min.)
Different ways pollutants end up in our water.
What Are Algal Blooms and Why Do They Matter? (article & video, 3 min.)
This article includes a video describing research in Canada that has helped improve water protection policies around the globe.
How Does Climate Change Affect Biodiversity? (video, 12 min.)
Global warming explained and its impact on biodiversity.
Protecting Biodiversity: The Power of the Individual (video, 10 min.)
Included in this video are the benefits of citizen science and its important contributions to environmental research.