Wade in for the river at the annual Bernie Fowler Patuxent River Wade-In, linking arms with the retired state senator, Gov. Martin O’Malley, Congressman Steny Hoyer and Maryland Senate President Mike Miller until you can no longer see your feet. The resultant sneaker Index shows how the water quality of the river has changed over the years. Listen to speeches and music, wade in, then stay for a picnic. 1pm at Jefferson Patterson Park, St. Leonard: 410-586-8501; www.jefpat.org.