Just be very careful. You might want to check what kind of concrete it is. Concrete will leech lime and can kill everything. Those that have a watergarden can not use certain concretes because of the lime. Like sometimes people will want to use concrete blocks in their ponds to lift plants up and that is a big no no.
You can do a search on Yahoo and just put in "Concrete Leech Lime", and you can read all about it.
For years I was a watergarden/Pond Master Gardner certified through PondScapes Magazine and the issue of concrete would always come up with new pond owners.
I wish you the best.