“Since at least 1992, Christo and Jeanne- Claude have pursued “Over the River,” a project to cover 6.7 miles of the Arkansas River between Cañon City and Salida with translucent fabric panels 10 to 23 feet above the water. But the controversial husband-and-wife artistic duo set it aside several years ago to focus on “The Gates.” After a three-week display that New York City officials estimated drew 4 million people, including 1.5 million from outside the five boroughs, a question arises: Will the couple shift their focus back to Over the River?”