Ballinderry Rivers Trust is counting the cost of damage to an education resource at Orritor on the outskirts of Cookstown.
Vandals attacked a large section of the boardwalk, leaving the mussel breeding tanks inaccessible.
Condemning the "mindless destruction", police described the facility on social media as "a vital community education resource" used to teach children about the water cycle and life in the river.
It is estimated that approximately £1,000 of damage was caused in the incident.
If you have any information about the incident, contact Constable Semple on 101, quoting serial 427 22/08/2018 or by contacting Crimestoppers anonymously on 0800555111.