Only since 2009? It's been open for at least two years now.
Well the story says 2 of every animal so it must be pretty bloody huge.
A friend of mine wanted to visit it recently but found that noah's ark was closed due to heavy rains or bad weather.... Talk about the irony
The dimensions are actually in the bible:
Genesis 6:15b
New International Version (NIV)
15 This is how you are to build it: The ark is to be three hundred cubits long, fifty cubits wide and thirty cubits high.[a]
a. Footnotes:
Genesis 6:15 That is, about 450 feet long, 75 feet wide and 45 feet high or about 135 meters long, 23 meters wide and 14 meters high