ash, mud, sand, the army corps of engineers starred dredging that immediately after the eruption and that process went on for years after mount st. helen s erupted in 1980. the seattle times books back today saying the amount of stuff they dredged out of the rivers was enough material to build a 12-lane highway from new york city to san francisco.3รง 12 lanes. they dredged all of that stuff to keep the rivers going. and they piled it up on the banks. next to the rivers. and the little up to of causal rock, washington, the dredge piles where dozens and dozen of acres basically created this moonscape of this dredged-up ash and sand and sediment that nobody knew what to do with but they had to do the dredging to try to save the down. above castle rock is a lake called spirit lake and spirit lake took the brunt of this
they had to do the dredging to try to save the down. above castle rock is a lake called spirit lake and spirit rake took a brupt of this eruption. spirit lake had so much sediment dumped into it by the mount st. helen s eruption that the surface level of spirit p lake rose by 210 feet. and that s up above castle rock and so that nightmare, that potential nightmare, is looming over the town of castle rock. and it still is. they eventually built a tunnel to channel outflow from that lake so it would not loom so dangerously for the town. now 35 years later they are worried now they might have to go in and widen that tunnel because it s filling up today with that sediment again and threatening the town again. mount st. helen s blew up 35 years ago today. it killed 57 people and it changed the shape of the earth. it moved rivers, turned a