It's a cultivar of Juncus effusus, similar to 'Spiralis' or 'Unicorn', commonly referred to as corkscrew rush. It is a marginal aquatic, meaning it can take poor drainage and occasional flooding. Placement directly in your pond is not a great idea, but placement along the pond edge is fine, so that the roots have a constant supply of moisture. Avoid much more than 3" of water over the crown for any extended length of time. It can also grow in regular garden conditions, provided it receives sufficient irrigation. Great for container culture also.

You don't indicate where you are located, but in mild climates Juncus has a tendency towards invasiveness. In colder climates it can die back in winter and re-emerge in spring.