Winter hits the Henry's Fork early!

You’re lucky this week, because my blog will be really short.  The reason for that is that it is already 4 p.m. on Friday, after two full days of working out in cold, snowy weather to get ready for winter—except that winter had already arrived on Monday.

Sunday afternoon, I spent the last few hours of our glorious fall fishing near St. Anthony, as dark clouds gathered and the wind picked up ahead of our first real winter weather of the year.  By Monday afternoon, temperatures were in the 20s and falling rapidly, with subzero weather forecast for the next few mornings.  This isn’t extreme weather for eastern Idaho in winter, but it is pretty unusual for November 10.  Numerous low-temperature records were set around the region this week.

Things that happen when this sort of weather sneaks up on us include suddenly realizing that the boats are sitting outside and are full of water from recent rain and that water is turning to ice in a hurry.  So, Brady and I chipped the rapidly forming ice off of landing nets and anchor ropes and got the rest of the water drained before it froze solid.  That was Monday afternoon.  By Tuesday morning, ice was starting to form on the river, causing large fluctuations in flow, as water was trapped behind ice dams and then suddenly released.  We talked with the operator of the power plant at Ashton Dam, and he said this is the earliest he has ever seen Ashton Reservoir frozen, and he has worked at the plant for over 30 years.  Managing the power plant is challenging when ice forms that quickly, but by Thursday, the reservoir was stable at its winter operational level—with a thick and stable cover of ice—and flows were steady.

On Thursday morning, Brandon and I headed to Island Park first thing, when it was about 5 below zero, to see if we could retrieve our automated water-quality instruments, which are called “sondes”.  These sondes are about 3inches in diameter and about 30 inches tall and record seven different water-quality parameters.  We retrieve, download, and re-calibrate the sondes every 8 weeks or so, and this week was the scheduled maintenance week.  Under average conditions, this would have been an easy task.  But when we got to Pinehaven to retrieve the first one, the river was frozen, except for a very small patch of open water right at the boat dock where our sonde is housed.  Dozens of trumpeter swans were walking around on the ice both upstream and down.  The specified lower end of the operational range of these instruments is about 25F.  When we removed the top of the 4” pipe that houses the instrument, all we could see was solid ice, and all I could think of was that I had just destroyed a $15,000 piece of equipment by not paying more attention to the weather forecast!  However, after breaking up some exterior ice and moving the pipe around, the ice plug inside broke, and we pulled the sonde out.  We repeated this process three more times—at Flatrock, Island Park Dam, and the old Marysville Bridge near Ashton—until we had retrieved all four sondes from the ice.  To my amazement and relief, all four were still operating perfectly and recording data. 

I’m going to quit while I’m ahead, however, and put them back in the river only when the weather warms up a little.  In the meantime, I have plenty of data to analyze—and more importantly—to use in improving management of the river.