In 2003 Friends of the Colo  completed the primary treatment of invasive willows along the Colo  River in the Wollemi NP. The group extended the project to treat black willows in the entire Colo Catchment which with a few exceptions was completed in  December 2006. In November the group completed its second biannual Monitorng trip in the Wollemi NP treating 48 black willow seedlings.