Mountain. Near the Riverdale Raceway, SR 504 intersects the east end of SR 505, which provides connections to I-5 and Toledo. The highway continues northeast into Kid Valley, home to camping sites and a few homes, and follows the south side of the narrower valley as the river meanders north and south around various mountains. At a third crossing of the river, SR 504 intersects a short spur route on Sediment Dam Road that leads to a viewpoint overlooking the Toutle River Sediment Dam. The highway continues along the northeast side of the earthen dam and its reservoir, climbing uphill and running through cuts in the cliffs. Further southeast along the river, SR 504 passes the privately owned Eco Park resort, a youth camp, and a heliport near the Hoffstadt Bluffs Viewpoint. The highway then crosses over Hoffstadt Creek on a steel truss bridge that sits above the valley floor; it is the longest of 13 bridges on SR 504. The bridge also marks the western extent of the "blast zone," where trees were felled during the 1980 eruption of Mount St. Helens, located away. The area has large forests of young fir, pine, and cottonwood trees planted by Weyerhaeuser in the 1980s as part of a regeneration and restoration project. The company also operates the Charles W. Bingham Forest Learning Center, a museum that overlooks the North Fork Toutle River and also includes a rest area. SR 504 continues further into the mountains, crossing Bear Creek and traveling around Elk Rock to a viewpoint on its southeast side. From the Elk Rock area, the highway forms the northern boundary of the Mount St. Helens National Volcanic Monument and encounters more mountainous terrain that results in several hairpin turns between other scenic viewpoints. After crossing several branches of Maratta Creek, SR 504 reaches a partial cloverleaf interchange with an access road that serves the Coldwater Science and Learning Center, a visitor center that overlooks the mountain and open from autumn to spring. The highway heads west before completing a hairpin turn to travel south around the end of Coldwater Lake. Beyond milepost 45, SR 504 is closed during the winter months due to hazardous conditions for drivers and potential avalanches. The highway continues into the National Volcanic Monument and turns east before reaching the border between Cowlitz and Skamania counties. SR 504 follows South Coldwater Creek upstream through a narrow