Ice Jam Floods

When do you expect flooding?

It depends very much on where you are, of course, and what causes the flooding. Here in interior Alaska we have two flood seasons, with two quite different mechanisms, and we’re starting into one of them now, at the driest time of the year.

Yes, April is our driest month and May, while a little wetter, is the second driest month with temperatures above freezing. So why flooding now? Why not in the rainiest month, August, which did produce the great Fairbanks Flood of 1967?

Two words: ice jams.

We’re already getting some information on river breakup and flood warnings. In fact, there is an ice jam flood advisory on the Tanana River near the mouth of the Salcha (upstream of Fairbanks) today and tomorrow. Most of the rivers in Alaska run from highlands with snow — lots of snow — in the winter months to coasts that during the spring are a lot colder than the interior where the snow is melting under the sun. The snow melts and the meltwater runs into the river while the lower reaches of the river are still frozen. As the river rises and the sun weakens the ice that has covered it over the winter, the ice breaks into chunks and slabs and begins to flow with the river. It used to be axiomatic that rivers could not be crossed, and bridges were often swept away, during breakup, when the ice is carried downriver. When I came to Fairbanks it was still a possibility that the last car of the year over the ice bridge across the Chena River would go through the ice. The great gambling event of the Alaskan Spring is the Nenana Ice Pool – wagering on the exact day, hour, and minute that the ice will go out at Nenana, Alaska.

But all that ice moving downriver can cause problems, too. It’s not wimpy, thin ice; the ice at Nenana is over 2’ thick today, and while it’s thinned from is original 3 ½ feet, it still makes big chunks. If it piles up, as may happen at a different place every year, the flow of water is severely impeded, and the water spreads out over the adjacent land. Rivers in Alaska are transportation corridors – not only for boats in the summer, but for dog teams and snow machines in the winter. Consequently most of the older settlements in Alaska are on this precursor to our skimpy road net, and they almost expect to be flooded in spring. Fuel lines and tanks must be tied down, as must boardwalks, lest they float off. Belongings are put up high. I expect the public service announcements warning residents to prepare for flooding to start soon.

By the way, notice that our wettest month has an average precipitation of under 2″, and the annual total is only 10.31″. In terms of total precipitation, I live in a desert.

The Fairbanks Flood of 1967

Floods in Interior Alaska occur at two times of year. The first, which is expected by anyone who lives near a river in Alaska, is breakup floods. April is our direst month, but the melting snow is dumping tons of water into the rivers, and ice jams can form temporary dams, never in the same place twice, which lead to major flooding in the villages. A couple of weeks ago a public service announcement included a story of a small boy who was frustrated when the local teacher refused to put things up high during flood season in spite of warnings from his pupils. “You should have listened to us old-timers,” the children told him after he and his family had to be evacuated in a boat.

But one of the greatest floods in Fairbanks history occurred during the second flood season, in late August.

If April is our driest month, August is the wettest. During the summer of 1967, the rains started in earnest in July, and the Tanana river began rising from more than melting glaciers. At that time the only road into Fairbanks was the Richardson Highway, which runs along the north bank of the Tanana. That river is just south of Fairbanks, and the road had already been washed out in places by early August. The nearest upstream bridge was 100 miles east; there was at that time no highway bridge downstream that connected to anything. Fairbanks itself is built where the Chena, a smaller, meandering river, flows into the Tanana.

In mid-august the southwesterly flow from the Bering Sea, augmented by the remains of a typhoon, began dumping unprecedented amounts of rain in the headwaters of the Chena River. By Monday, August 14, it was apparent that flooding would affect Fairbanks, which is on a double flood plain. The university is located on a hill and Al George, the civil defense coordinator, announced that the 300 extra beds in the dorms would be available for refugees.

The next morning the radio sounded totally confused as to what was going on. I looked across the street, saw that water was pouring into an excavation and beginning to flood a trailer park, and stuck the cats, their food and whatever was in the powerless refrigerator in the car when I went to work. Luckily! By that time the 300 beds had been expanded to wherever people could be put, which included everywhere except the power plant—on lower ground and itself in danger of flooding. (The city and Borough power plants had already been flooded out.) For most of the next week, I was the room clerk at the Geophysical Inn or helping distribute supplies for the Salvation Army. The intersection I’d driven through at 10 am was deep enough to float trucks by noon, and it was several days before I could get home. I did have luxury quarters—the floor of the office I normally shared with my Thesis advisor. Other offices often housed several families.

I was also able to reassure my family almost at once. The Geophysical Institute at that time was heavily radio-oriented, and a number of ham radio operators were our main contact with the lower 48 states. By the time the flood was a day or two old, the operators were overwhelmed and the messages were pretty limited. I recall an old, crank-operated phone that was our link with Outside.

One of my jobs was to try to locate and check off Institute employees. Among the missing for the first couple of days was Dan Crevenston, the Assistant Director (I think — need to check.) Not until the army managed to get its high-wheeled vehicles running between the campus and the airport (which stayed inches above the flood water) did we find that Dan was helping run things at the airport – which had become another refugee center.

Looting was official, and wasn’t really looting. As I recall, local grocery stores donated whatever they had above water to the flood relief effort, and the army’s high-wheeled trucks moved it to the campus.

One sidelight if you’ve looked at the University’s official story. There is a photograph of the old Geophysical Institute in Part 3 of that story. The peculiar t-shaped structure at one end? Some of the stacked trailers we had offices in as we outgrew the building, prior to moving into the new building in 1970. (I’m probably somewhere it that picture.)