THE SNAKES IN THE POOL OF DINAS EMRYS: A WRONGLY LOCALIZED STORY?

The Lake of the Snakes in Snowdonia

I've been doing some map work.  The result?  I'm pretty sure the snakes/serpents of the pool at Dinas Emrys may owe their origin to a different location in Eryri/Snowdonia.  Or, rather, the snakes found at one place may have been fused in tradition with the 'dragons' (i.e. chieftains, warriors) found in cremation urns at the fort.

To demonstrate how this may have happened, it is first important to remember that the Welsh word llyn could mean lake or pool.  I've often wondered about the pool of Dinas Emrys in this context.  While there was a pool of sorts associated with the fort, the large lake below it was called Llyn Dinas, the 'Lake of the Fort'.  But this place-name could easily have been misconstrued at some point at the "Pool of the Fort.'

Just on the other side of Snowdon/Yr Wyddfa from Dinas Emrys there is a lake called Llyn Nadroedd, the 'Lake of Snakes.'  It is right next to another lake called Llyn Glas, and one called Llyn Coch (Goch).  

The river Glaslyn, named for its lake, flows right past Dinas Emrys.  The components Llyn Glas and Glaslyn are the same - only switched.  Interesting, we find on some maps the Glaslyn referred to as Llyn Glas:

There is yet another Llyn Glas over on the northeastern side of Snowdon:

I would also point out that issuing from the Llyn Coch [1] adjacent to Llyn Nadroedd there is an Afon Goch, the 'Red Stream.' There is also an Afon Goch emptying into Llyn Dinas at Dinas Emrys, AND an Afon Goch emptying into the Glaslyn south of Beddgelert where some maps render the river-name as Llyn Glas.

The reader will recognize immediately how easily these various identically named places, all in close proximity to each other, could have been misidentified with each other.  

Now, I've tried without success to discover why Llyn Nadroedd is called the Lake of Snakes.  Nothing so far.  But I have put all queries to everyone I could think of who might know of some aetiological story concerning the lake.  If any of my sources come up with an extant tradition that explains of the presence of snakes in/at the lake, I will post it here as an addendum.

For now I would like to quote a couple lines from the CAD GODDEU poem, attribuated to Taliesin:

Bum neidr fraith, ym mryn

Bum gwiber yn llyn.

"I was a speckled snake on the hill (or bank);

I was a viper in the lake."

A viper in the lake?  Well, I have written before about the Common European Viper in Britain, a species in which the background color in males can appear whitish and in the females reddish.  Which brings to mind the white and red dragons of Dinas Emrys.

However, Welsh neidr is cognate with Latin natrix, which specifically means a water-snake.  In Britain, the grass snake is often found hunting for prey around rivers, marshes and lakes.  See https://www.woodlandtrust.org.uk/trees-woods-and-wildlife/animals/reptiles-and-amphibians/grass-snake/.  The problem with the grass snake is that its colors do not in any way conform to those of the red and white serpents of the Dinas Emrys story.  

[1]

https://folklorethursday.com/folktales/welsh-folklore-the-bride-from-the-red-lake/