Here is an extract from the mentioned site:

“Arugam (Bay) (Ampare [Amparai])
ARAGAMA (ARAGAMTHARA), ARAGAMTHOTA)
Disc. A village donate to a temple is known as ‘aaraamagama’
10th century piller inscriptions near Kondavatavana ruins have used
the shortened “aaragama” to refer to an “aaraamagama” there
Karanda oya falls into the sea at aaragama
Legend. Arugam-bay should be aragamthara -> Araganthara
“Aragama”, means “that village”,
as pointed out to King Kavantissa.
Also Saigama, where “Sai” -> six -> “Aru” in T.
Both are unsubstantiated, “Jana Pravada”.
The ‘gama’ in S. is never used as such in T. where it becomes ‘kamam’.
Meaning. ‘Ara’ in S., and ‘Aru’ in T. refer to a water stream”