CROTON-ON-HUDSON Hudson River Sloop Clearwater, America’s flagship environmental organization, will host its 2009 Great Hudson River Revival at Croton Point Park, on Saturday and Sunday, June 20 and 21. Headlining the main Hudson, Rainbow and Dance music stages on Saturday will be contemporary blues star Susan Tedeschi and 1960s folk legend Richie Havens, plus Jay Ungar & Molly Mason, Philadelphia indie pop band Dr. Dog and A.C. Newman. On Sunday the headliners on the three main music stages will be Arlo Guthrie, Pete Seeger & Tao Rodriguez-Seeger and Elvis Perkins in Dearland and Manchado. A full festival lineup can be found at www.clearwater.org/festival/schedules.html. The revenue raised by the Revival goes to support Clearwater’s numerous educational programs and its work toward environmental and social justice, as well as keeping the Clearwater afloat. This year’s Clearwater festival comes on the heels of the star-studded concert event celebrating Pete Seeger’s 90th birthday.