A Mt. St. Helen's Warning to Officials in California

The one thing that the general public is very good at is taking risks. Most of us seem to think we are invincible and that bad things only happen to other people. With the evacuation of almost 200,000 people from below the Orville Dam, near Sacramento, it won't be long before elected officials start to get hounded by some of those people who want to get back to their property. There are lessons that can be learned from not a dam, but a volcano.

It was May 1980 and people had been evacuated out of an area they called the Red Zone Surrounding Mt. St. Helen's in Washington state where the majority of danger from an eruption was expected to come from. Here is an excerpt from a Wikipedia listing on the St. Helen's situation:

"Visible eruptions ceased on May 16, reducing public interest and consequently the number of spectators in the area.[18] Mounting public pressure then forced officials to allow 50 carloads of property owners to enter the danger zone on May 17 to gather whatever property they could carry.[18] Another trip was scheduled for 10 a.m. the next day.[18] Because that next day was Sunday, more than 300 loggers would not be working in the area. By the time of the climactic eruption, dacite magma intruding into the volcano had forced the north flank outward nearly 500 feet (150 m) and heated the volcano's groundwater system, causing many steam-driven explosions (phreatic eruptions)."

Well, May 18 was the eventful day of the eruption. If the officials thought that the eruption was coming on May 18, would they have let property owners in to collect their things? No, not ever — they didn't perceive the level of danger and events that were about to befall them. 

Dams can be dynamic structures and the decision-makers better "dam well" know what they are dealing with before letting the public back into a danger area.