Over the River. For nearly twenty years, artist Christo and his late wife, Jeanne-Claude, planned the "Over the River" project, a series of sunshades that hopefully will be installed in a few years as a temporary work of art on intermittent stretches of the Arkansas River in southern Colorado. It's not clear yet whether or not it will happen, though it is clear that a campaign has been mounted against it. In Denver, we're lucky to be just a few hours' drive from the proposed setting — and also to have the opportunity to carefully examine the idea through Over the River, Project for the Arkansas River, State of Colorado, a Work in Progress, on display at MCA Denver. The exhibit originated with Christo himself, and it suits well the mandate of the museum to encourage dialogue in the visual arts. The show is beautiful and coolly elegant, its coolness having something to do with all the blue sky in the mixed-media works on view. That coolness is also the perfect analogy for "Over the River," since the water, and the sunscreens, would have a cooling effect on viewers — if it's ever built, that is. Through January 16 at MCA Denver, 1485 Delgany Street, 303-298-7554, www.mcadenver.org. Reviewed November 4.