[KS] Is the Wikipedia article on the Tancheon "charcoal stream" myth correct?

[Knigel Holmes]

I've been looking for information on the Tancheon river and came
across this interesting myth:
http://en.wikipedia.org/wiki/Tancheon#History

After looking around, I've found that other sites reference the
Wikipedia article which has no citation itself. Do any of you, by any
chance, have some reference for this, or can you in any way confirm or
dis-confirm this as Korean folklore? I appreciate all of your help~

Also, if you know of any interesting facts about the Tancheon River, I
would be grateful for that information as well.

I see this river every day outside of my window and would like to know
it better.

Kindness,
Knigel

"The Tancheon's name, is believed to be connected to Dong Bang-sak
(동방삭, 東方朔), about whom many legends have come down to Korea via China.
He lived during the time of Chinese emperor Han Wudi (156 BC - 87 BC),
the seventh emperor of the Han Dynasty. Because Dong Bang-sak received
the love and attention of the emperor for his great wit and his
ability to make good decisions, he was awarded with a high government
post. Perhaps, though, more so than these talents, he was most famous
for the fact that according to legend he had lived more than 3,000
lifetimes (180,000 years).

It is believed that his long life came from picking and eating peaches
at the stream of Seo Wong-mo (서왕모, 西王母), the Chinese goddess of
immortality. For this, he became blessed with unnaturally long life.
Some say, however, that the fact he lived a 3000 thousand lifetimes
was an exaggeration caused by the slip of a brushstroke. He may have
actually only lived 30 lifetimes. At one point, the Chinese characters
for thirty (三十) may have accidentally come to be read as three
thousand (三千), by someone adding one extra stroke to the top of ten,
making it appear as one thousand. Of course, we cannot say for sure.

Nevertheless Dong Bang-sak, with his long life, proved to be an
irritation to the spiritual world. In the eyes of many spirits from
the underworld, he had cheated death once too many times. So eager
were they to catch him, and bring his soul with them to the afterlife,
that they searched everywhere for him. However, as he was quick of wit
and a man of immeasurably great wisdom, their efforts were always in
vain. In fact, on many occasions he would even receive the spirits who
managed to track him down, as guests in his home. After a short period
of entertaining them, he was able to send them on their way without
even so much as a struggle. So skilled was he at persuasion, that in
no time he had the spirits believing they had mistaken him for someone
else. They would then go off again searching, never the wiser as to
this man's true identity.

One spirit, who was determined to be fooled no longer, thought about
the problem seriously. After deep contemplation, he came up with a
cunning plan that would surely allow him to capture Dong Bang-sak once
and for all. As it happened, Dong Bang-sak was one day passing over
the Tancheon. There, he came upon someone washing clothes in the
stream water with a piece of charcoal. It was, in fact, the spirit
disguised as a human. Unable to resist this unusual sight, Dong
Bang-sak asked, "Why are you using that charcoal to wash your
clothes?"

The spirit replied, "Because charcoal gets them whiter, of course!"

Upon hearing this Dong Bang-sak burst out into a ferocious laughter
and said, "Ha! My boy, I have lived 180 millennia, but never have I
heard of someone making clothes whiter by washing them with charcoal!"

With this slip of the tongue, the illusive Dong Bang-sak had given
himself away. The spirit at once knew that he had at long last found
the man whom he had been looking for. He then quickly apprehended Dong
Bang-sak and took him to the underworld, bringing to a close the life
of this long lived man of wit and deception. From this, though, we
have the name for this well-known body of water in Bundang, the
Tancheon: The Stream of Charcoal. "