It is now becoming cleaner as many people and groups work to restore its watersheds, monitor its waters, and establish policies to secure its future quality. For more information on Lake Michigan , see Other Information Resources and Regional Watersheds . Carefully managed, many parklands coincide with and define environmental corridors . Since 1937 Milwaukee County has provided parklands for its 19 municipalities. With picnic grounds, playgrounds, more than 90 miles of bike and off-road paths, and as habitat for many wild animals and plant species, the parks do much to sustain both human populations and natural processes.
Some parks also maintain fishing lagoons.
Annual plant sales the last two weekends of May. 10340 Watertown Plank Rd. One of the greatest threats to Milwaukee parklands is the invasion of non-native plant species which crowd out native plants and reduce biodiversity in local habitats. In response, a local citizen advocacy group has developed a volunteer program to remove invasive plants by hand. A 20-acre offshore park made of rubble from the Milwaukee Metropolitan Sewerage District's Deep Tunnel Project, this will be the first new state park since 1978. It will link Milwaukee County's Oak Leaf Bike Trail and the Hank Aaron State Trail, which will run through the Menomonee River Valley.