“I don’t know if it’s normal I just haven’t seen it that low; it appears like a chemtrail-type situation off your left wing.”
When the pilot asked her to repeat it, she said:
“It looks like a chemtrail off your left wing, I just have not seen it that low before, but it does look similar to a…”
Her transmission is cut off before she can finish her sentence. When you hear her again 10 seconds later, she alters her phrasing to say:
“Alright, a contrail off your left wing.”
The pilot does not appear surprised or concerned.
You should then be able to download the file “KPDX-Twr-Sep-22-2016-0100Z.mp3”
The relevant part is about 18 minutes and 40 seconds into the file.
Special thanks to http://stopsprayingus.com for making the file and transcript available.