You can see my views on music in magic in my post
Summary of Magic in the thread
magic in Middle Earth.
As for Ivrin, do you remember the refrences in
The Hobbit about Smaug's fumes and his "reek". Glaurung as the father of dragons would probably be very "toxic" so to speek. That would be enough to defile the waters. Also if I remember correctly Ivrin was a very clean, wholesome, almost sacred place. The very presence of those foul creatures would be enough to "defile" its waters.
For my views on the stones of Eregion and other inanimate objects check out
my post in the thread
The Gift of Speech
I know that the effort of clicking on a link to see my replies is a great one,
but I encourage you to do so. I would very much like to discuss my ideas in these areas whether it is praise or criticism.