Actor Robert Redford is returning to Washington later this month to promote the documentary “Watershed” at the D.C. Environmental Film Festival. Redford will join EPA head Lisa Jackson on March 24 at the National Museum of American History and introduce the film. Redford narrates the documentary, which looks at the lives of six people working in the Colorado River basin. He also served as executive producer. His son James Redford also produced the film. Unfortunately for Redford fans, tickets for the screening have been snapped up, but there will be a stand-by line if any seats remain.