Wading in the icy Yukon River to maintain measuring tools

EAGLE – Snow geese flew in a jagged V overhead, gasping as they gazed at the bumpy face of Alaska for the first time in 2022.

Nine hundred feet below, the Yukon River flowed quietly, except for the thud of icebergs skidding along the river bottom near the shore.

Sensing a break in the ice traffic, US Geological Survey hydrologist Heather Best – wearing waders with a hole she would soon discover – entered the river. In both hands, she held a 3-foot portion of grader blade. Running along the blade was a river measuring tube secured by hose clamps.

This piece of steel contained the business end of a device that Best and others use to measure the flow of the Yukon River in Eagle, a town of about 110 people just downriver from the Canadian border.

A few days earlier, ice formed by cold winter air had disabled the river’s measuring instrument. When the river broke up at Eagle, rising meltwater lifted a layer of ice that had been in place for most of the winter.

The brown water then carried huge shards of ice downstream at about 5 miles per hour. Some of them crashed on the bank in an outside bend in the river just below Eagle. These icebergs ripped the river measuring pipe from the shore where it entered the river, shearing it in a few places.

Liz Richards, a hydrology technician for the USGS, pulls an anchor attached to a river level measuring device from the Yukon River

Best and USGS hydrology technician Liz Richards had come from their office in Fairbanks to see if they could fix the river’s measuring instrument. They stopped on other waterways during the 10 hour journey, to see if the stream information being sent over the internet was accurate and to fix things that broke down when the winter ice turned to water.

On the shore of the Yukon River, after an hour of work that included scrambling over chunks of ice the size of scoops, Best and Richards had spliced ​​the measuring pipe to where the ice had cut it. They put it back on the grader blade. Then came the trickiest part – redeploying the tube below the surface of the Yukon.

Trying to keep her immersion time in the freezing water to a minimum, Best avoided rocks she couldn’t see below the surface. Once the river reached the belt around his waist, it stopped.

Best pushed the grader blade as far into the water as she could. She then retreated to shore.

“Nice job,” Richards said from a sliver of gravel shoreline in front of a pile of ice.

“Hopefully it’s deep enough,” Best said.

[Yukon River breaks up at Eagle, leaving residents relieved]

The submerged end of a pipe would release bubbles of nitrogen into the river in a complicated and somewhat magical system that converts the water pressure sensed at the opening of the pipe underwater to the depth of the river.

Best said the underwater end should be deep enough to stay submerged for weeks to come. If not, she or someone else would have to come back in midsummer, after the river level drops, to throw the grader blade a little deeper.

“We need at least 4 feet deep,” she said.

USGS hydrology technician Liz Richards, left, and USGS hydrologist Heather Best repair a river level measuring device that was damaged by ice during the Yukon River breakup

Carrying pieces of broken pipe and a cardboard box of equipment and tools, Best and Richards headed up a steep incline, reaching a small cedar cabin on a grassy bench near the National Park Service field station at Eagle.

Inside the structure were the plastic pipes, glass bulbs and nitrogen tanks that make up the ‘Conoflow gas purge system’, an essential part of the river and stream measurement sites of the ‘USGS across the country.

After fiddling with the system a bit, Best got some good news.

“Looks like it’s in five feet of water,” she said.

“Yeah,” Richards said.

The women then tidied up the small shelter. Best closed the door and padlocked it, and the couple headed for their car, which would take them a few hundred yards to their room overlooking the big river. They would drive out of Eagle onto the Taylor Highway the next day, doing some more fieldwork on the way back.

As for the town of Eagle, geese continued to pass in mixed flocks, songbirds flooded the local aspens, and people reported seeing the first returning swallows.

The river, nearly ice-free but soon swollen with water from winter snowmelt still in the mountains of Canada and Alaska, has again seen its level visible to people far from Eagle, the website from the USGS.

About Octavia A. Dorr

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