River running through the middle. Today, the lake borders the Town of Koshkonong on its eastern side, and the Town of Sumner on its northern side. Ecology Vegetation Lake Koshkonong has seen many vegetational changes in the past 150 years. Once a deep-water marsh covered with emergent vegetation, the lake was predominantly wetlands filled with reeds, wild rice, and grasses. The wetlands have significantly disappeared since then due to rising water levels caused by higher dams and the ever changing landscape. It is estimated to have lost over 100 acres of wetland by 2000. Now, the large pool of water known as Lake Koshkonong has been replaced by lake sedge (Carex lacustris), bur-reed (Sparganium), and other aquatic species. The lake association has been trying to introduce Pondweed and Wild celery to improve fish habitats. Fish Throughout the Rock River (Mississippi River tributary) and Lake Koshkonong around sixty species of fish can be found. Many of those species are river spawners, meaning the release of gametes from the body occurs in the rivers even though they might spend their whole life in lakes. Floods and droughts will both affect spawning of different species of fish, enhancing the amount of some and depleting others. Here are a few species of fish that can be found in the lake. Muskellunge, Panfish, Largemouth bass, Smallmouth bass, Northern pike, Walleye, and Catfish. Birds In the surrounding habitats of Lake Koshkonong's riparian wetlands, many endangered species of birds can be found. The rising water levels have an unfortunate impact on these species. Loss of trees, herbaceous vegetation, and groundwater dependent wetland plants will effect the species they support. Some of the rare species found in this area that are impacted by rising water levels and habitat loss are the Cerulean warbler and the Acadian flycatcher. Other rare species of birds that are being affected are Black tern, Forster's tern, American bittern, Least bittern, and Virginia rail. Tourism and recreation Summer attractions Lake Koshkonong is well known for its great fishing seasons. Hook and line fishing is open all year round with restrictions on some species including Muskellunge, Lake Sturgeon, Trout, Paddlefish, and other endangered species. Muskellunge and Hybrid season for 2020 was open May 2, 2020 to December 31, 2020 with a minimum length limit of 40 inches and a daily bag limit of 1. For fishing to be able to occur on the lake it