Lake Ecology

Understanding lake ecology

Lake ecology has a big impact on lake health. Native and invasive species can interact in complex ways, even impacting water clarity and our economy.

Learn more about key topics:

The following organisms are present in the Madison lakes and can have a big impact on water quality.


Cyanobacteria blooms can close beaches and even release toxins – learn more about cyanobacteria.

This recently-discovered invasive species is radically changing the ecosystem of our lakes – learn more about zebra mussels.

Learn about two tiny organisms that have a major impact on water clarity in our lakes – learn more about Daphnia and spiny water flea.

Despite their longtime presence, carp are considered an invasive species with harmful impacts on native ecosystems – learn more about carp.

Eurasian watermilfoil was first recorded in lake Mendota in 1962 and can now be found in all of Madison’s lakes – learn more about Eurasian watermilfoil.


About the lakes

The 62-mile long Yahara River connects lakes Mendota, Monona, Wingra, Waubesa, and Kegonsa in a chain that winds through south-central Wisconsin. Learn more about each lake, and follow the links to lake-by-lake pages with annual updates on water quality conditions.

Lake Mendota - Union - Thomas Klingele

Lake Mendota is the first and largest lake in the Yahara chain – learn more about Lake Mendota.

Katie Wheeler - Lake Monona

Lake Monona is the second lake in the Yahara chain – learn more about Lake Monona.

Lake Wingra

Lake Wingra is the smallest Yahara lake, connected to Lake Monona via Wingra Creek – learn more about Lake Wingra.

Aquatic Plant Harvesting on Lake Waubesa

Lake Waubesa is third lake in the Yahara chain – learn more about Lake Waubesa.

Ice Boats on Lake Kegonsa

Lake Kegonsa is the fourth lake in the Yahara chain – learn more about Lake Kegonsa.