Carson WA is just on the other side of the Columbia River from Bonneville and it is the gateway to the Gifford Pinchot NF, and the Old Man Pass which takes you to the eastern side of Mt St Helens. Old Man Pass is a very quiet road but worth traveling. 
Close to Mt St Helens we traveled on the boundary of the blast zone and Clearwater Creek is visible in the deep valley below. This area is framed by the trees that were killed at the edge of the blast cloud that scoured and sterilized everything in its path. Here we first saw the vastness of the devastation caused by the last eruption, and it raised our interest levels to more closely experience this volcano. 
We were on our way to Paradise Resort also a Thousand Trails resort at Silver Creek just west of Morton WA being the biggest town in this area as it is centrally located between Mt St Helens and Mt Rainier.
Mt St Helens was our closest attraction and we visited this remarkable volcano and its eastern / northern surroundings on the first day. By this time we have seen our fair share of volcanoes and I was wondering what more there is to see, but from what we saw the day before this one looked promising. I soon realized that each Volcano has its own personality, unique history and it impacts the weather and surroundings in many different and interesting but also devastating ways. That is why no volcano is alike. The only similarity is that you stand in absolute amazement and disbelieve, realizing how minute and vulnerable you are against the powers of nature. The first observation that strikes you is the white murky color of the Toutle River and as you travel upstream you pass Kid Valley still miles from the volcano on the banks of the river with a big concrete bear sculpture called “Big Foot” overseeing your every move and a souvenir shop. Not much of attraction at first glance, but when you stroll around you start to see the evidence of the 1982 eruption, a mere 30 years back. I still remember eruption from my younger days but visiting this site turned it into reality. This area was totally devastated by and enormous wall of mud and debris. Just 3 days before the eruption a couple left their unfinished A frame house and the area for reasons not explained and 3 days later it was flooded by a 30 ft Lahars (volcanic mudflows). Still visible today, is a metal frame of a fridge buried in mud with tree trunks scattered around imprinting the devastation in your mind. Today the house is still not occupied as it stands in a pit of water after the inside was excavated to show the dept of the mud at the time.
The visitor centers and the rangers provided us with a very dramatic but realistic history and overview. Mount St Helens is an active stratovolcano south of Seattle and Northeast of Portland and it is located in the Cascade Range of mountains which is part of the Cascade Volcanic Arc also know as the Pacific Rig Of Fire. It is well known for its 18 May 1980 catastrophic eruption of ash explosions and pyroclastic flows. Weeks before the eruption the north side of the mountain start to grow / swell 4 ft a day. What they did not expect was that the massive collapse of north side of the volcano causing a mighty sideways blowout to the north. The near supersonic lateral blast reached 500 - 800 F and instantly killed every living thing (trees, vegetation, fish and humans) within about 10 miles of the north side of the volcano. The hot steam, ash and hot gas engulfed the area with a force sufficient to strip huge trees bare and uproot or break them off at ground level. Trees were blown down like matchsticks stripped if the leaves and branches.
When we were there th crater was clouded so I borrowed the above from Wikipedia
Beyond the 10 mile radius it caused serious burns to humans, animals and vegetation. The avalanche of rock and mud roared over Spirit Lake, once a very pristine lake and holiday resort and the valley of the North Fork of the Toutle River, burying them under layers of rock, mud and ash up to 600 hundred feet thick. This was the largest debris avalange in memory the magna burst forth into a large scale pyroclastic flow moving at speeds between 50 and 80 miles per hour, flattening everything over 230 square miles. The waters of the Spirit Lake was blown up the steep northern side of the mountain and when the water returned to the lake it was filled with 360 ft of rock lava and debris doubling the size of the shoreline. This debris, water, snow and glazier ice created the lahars. This eruption was 10 times more powerful than what was expected. The sequence of events from the triggering earthquake through the entire blowdown took only five minutes. The unroofed magma column continued to jet upward for the next nine hours into a 15 mile high ash cloud.
It was the deadliest and most economically destructive volcanic event in the history of the United States. Fifty-seven people were killed; 250 homes, 47 bridges, nearly 7,000 big game animals, 15 miles of railways, and 185 miles of highway were destroyed. A massive debris avalange triggered by an earthquake measuring 5.1 on the Richter scale caused an eruption that reduced the elevation of the mountain's summit from 9,677 ft to 8,365 ft, replacing it with a 1 mile wide horseshoe-shaped crater. Much of the mud finally came to rest in the Columbia River where it clogged the navigation channel. It took 6 months of dredging to restore the shipping route.
The sediment in the rivers water is still as a result of the ash / pumice being washed away by melting snow waters.
Although the devastation was sudden and catastrophic, the recovery taking place in the following years has been almost as dramatic and scientists are amazed at natures ability to recover. Even in the blast zone where the land looked as if it had been scoured and sterilized, surprising evidence of surviving life started to emerge in the first weeks after the eruption. Nothing on the surface survived, but under the ground, roots of dormant plants, colonies of ants, and some small animals like pocket gophers and deer mice were able to escape the holocaust going on overhead.
The land outside the National Monument boundaries, are owned by private companies, who started an aggressive reforestation program by replanted millions of small trees.
Inside the monument boundaries 110,000 acres have been set aside to study Nature's intricate process of healing itself. Educated guesses are that in 50 years a healthy young conifer forest will be growing -- a mature forest could develop in 100 years -- and in 200 years it could look like other old-growth forests of the northwest.
The U.S. Army Corps of Engineers build a sediment dam to trap the sediment and to control floods and mudflows that are expected to course down the North Fork for many years. Since then the streams have become more clear and hospitable every year, but a new obstacle for migrating fish has come in the form of the sediment dam and spillway built just upstream from here in 1986-1989. To ensure the fish safe passage to their spawning grounds this fish lift was established. The fish coming up the river are trapped here, loaded into tank trucks, and transported to a release point above the dam.
The area where the fish traps are now was covered by a large mudflow seven hours after the 1980 eruption began. The thick flood, described by witnesses as having the consistency of warm concrete, reached heights of 20 to 30 feet above normal river level. Much of the flood water apparently originated from the water-soaked avalanche debris up the valley, squeezed out as the deposit compacted. The crest of the mudflow moved on downstream destroying about 200 homes, carrying some away and burying others. It crested at Castle Rock on the Cowlitz River about midnight, 30 feet high and 85 degrees F warm. Moving on down into the Columbia River the mud settled into the shipping channel, reducing its depth from 40 to 15 feet. Ocean ship traffic to and from Portland was disrupted; it took six months of dredging before shipping was fully restored.
Link to my blog: http://hseksteen.blogspot.com/
http://en.wikipedia.org/wiki/Mt._St_Helens
