Jeroen Phillipona wrote (in dutch): The plate next to the tree says 58 metres. An American tree-expert Robert van Pelt has measured 36.2 metres in 2005. van Pelt measured a height of 35.4 metres. Next to that he gave an interesting link with some more information.
http://www.conifers.org/cu/Taxodium_mucronatum.php
It is almost as if the 30 meters you can quote are not enough for this tree because as the official biggest tree in the world its trunk had a circumference of way more than 35 meters up to 46 - all these different informations are very confusing - do you have trustworthy numbers?