I’m in south central PA and haven’t taken the probes out of the water for the winter. It seems like that would defeat the purpose of monitoring conductivity spikes from road salt – after snow storms.
I know that the CTD probe isn’t supposed to freeze but I am leaving it deployed and checking it weekly when cleaning probes/swapping data cards.
The mayfly that I am using was deployed by a previous employee (since retired) at a different location and I think that it might have iced over in that deployment. The depth data that I’ve been collecting has consistently been 265-270mm less that the staff gauge and I’ve been tracking the offset on a spreadsheet. However, since the week of 12/27/22 the depth offset has been more in the 240mm range. There was a severe cold snap around/just after Christmas and the edge of the deployment stream was frozen but it didn’t seem, from what I saw, that the probe was frozen or encased in any ice.
I’m hoping that the data will stabilize at a certain point and that the offset could possibly be programmed into the mayfly so that the depth reading is accurate – but the stabilization may not happen (or the range/variation) may be too great or random. At which point it would probably be time to replace the mayfly because it is a first generation model that may not have seen the care that it needed.
So, after all of this, I think that the unit is supposed to remain deployed over the winter, but I’m not sure ho to protect the probe from freezing. Your board and data ought to be ok otherwise, especially if your battery is getting and providing enough voltage.