didn't the Navy quit using ELF (with those really really long cable antennas in tow) due to marine wildlife damage?
afk a while just started digging
https://www.navysbir.com/07_2/39.htm (detection - maybe real reason)
this references Michigan & Wisconsin (there is a sub base / sonar research in non-coastal Idaho too - Farragut kek) but the link is wrong.
https://science.slashdot.org/story/04/09/30/007228/navy-elf-to-be-scrapped
did get to this with pix from Wisconsin and power lines disconnected in Wyoming at night fro transmitter.
http://www.navy-radio.com/commsta-elf.htm