Monona Bay is a small, shallow body of water. It is about one-quarter square mile, with depths ranging from an average of 5 feet to a 13-foot hole on the south side.

Monona Bay is part of Lake Monona, which is a drainage lake. All of the lakes in the Yahara River chain (Monona, Mendota, Kegonsa, and Waubesa) are mainly fed by runoff via the river. Limited groundwater and rain also supply water to our lakes.

The Yahara chain of lakes are eutrophic -- they are very "productive" in that they support a large amount of lake weeds and fish. Like all eutrophic bodies of water, Monona Bay has a large amount of organic matter at the bottom - mostly decayed aquatic plants. This eutrophication of Monona Bay, and other Madison lakes, was mostly brought on by sewage practices during the 1800s, which degraded the lakes and promoted the growth of lake weeds and algae.

Unlike other bodies of water in the Madison area, Monona Bay has virtually no natural shoreline. The shoreline is fortified with bare rock to reduce erosion caused by changing water levels, wave action and ice heaving.