A key part of the Department of Conservation’s (DOC) work is to ensure the diversity of New Zealand’s natural heritage is maintained and restored. However, is a huge task and DOC’s resources cannot stretch to do everything everywhere. DOC therefore has to make decisions about what work to do and not do, juggling limited resources while meeting both biodiversity and community needs. To help make these decisions, DOC has developed the Natural Heritage Management System (NHMS) Programme which identifies the highest priority sites (both terrestrial and freshwater) that need to be protected and where work needs to be done. For NHMS to correctly identify the priority sites and what work it needs to be done at the sites, it relies on good information. For the freshwater sites, the data came out of the Freshwater Ecosystems of New Zealand (FENZ) dataset. This data set describes the environmental and biological patterns in NZ’s freshwater ecosystems (rivers, lakes and wetlands). Once priority sites have been identified, it is important to understand what pressures the sites face and what activities, including pest control, need to be undertaken to reduce these pressures. In this presentation, the Rotorua lakes, with particular reference to Lake Okataina, will be placed in the context of this prioritisation process, the pressures they face and pest control activities DOC has identified as necessary to ensure the priority lakes are protected.