The Historic Columbia River Highway is closed below Rowena Loop between The Dalles and Hood River due to a rock slide that occurred on Sunday.  Oregon Department of Transportation spokesman Peter Murphy says crews are still assessing the situation, and there is no estimate on when Highway 30 will reopen.  He said they are dealing with an overhang that leaves open the question of whether everything that could fall has done so.  Murphy says crews called scalers will be brought in to move down from the top of the hillside and make sure anything that could fall is removed.  The slide is also rather large, over 75 feet long.  Another question is whether some of the bigger rocks in the slide can be moved out by ODOT equipment, or if they will have to be crushed first.