Ms Simmonds and her team have planned an extraction for the seal if required.
One report from a local angler placed the seal at Llyn yr Afanc, Betws y Coed, which she described as “very deep” water levels at the time.
“From what I can tell it’s heading in the right direction,” she added.
“The best case scenario would be for the rescue team to find the seal and transport it back to the coast if it has not made it already.”
Ms Simmonds said it was “impressive” that it had made it so far considering a seal’s nature.
“Just looking at the river today and how high it is and how fast the water is flowing, I suspect it’s been given a nice lift back out.”
Ms Simmonds said her team was focusing on the changing seasons and how they could impact Wales’ colonies.
“At the end of August you start to see large numbers of seals returning to the north Wales coast.”
She said young seals could be “quite curious” as they try to “figure out the world”.