The major risk to estuaries in the region results from pressures related to increasing sediment loads and the disturbance or removal of biota. Generally, the overall risk of damage to the estuaries of the region due to stress from bacteria/pathogens, freshwater flow, habitat removal/disturbance, hydrodynamics, litter, nutrients, organic matter, pests, pH and toxicants is "low" or "negligible". This corresponds to "good" or "excellent" condition in relation to most of these stressors (i.e. bacteria/pathogens, freshwater flow, hydrodynamics, nutrients, organic matter and pH). However, despite the calculated low risk, the condition of estuaries in response to habitat removal or disturbance, litter and toxicants showed a poor or very poor condition. Sediments, biota removal/disturbance, habitat removal/disturbance, litter and toxicants are therefore identified as the key stressors in the region in priority need of manage actions. Currently, there is no data on the occurrence of marine pests within the region.

As part of the Queensland Government"s Stream and Estuarine Assessment Program an estuarine assessment framework has been developed for Queensland. This assessment framework has been used here in the Burnett Mary region to produce this State of the Estuarine Environment report. The assessment is based around a pressure-state-impact indicator framework but differs from most other monitoring programs in that it specifically links condition information directly back to pressures (and risk) and hence supports management decisions. The framework is based around a set of key stressors that can potentially impact on estuarine waterbodies. Stressors are defined as components of the environment that when changed can affect the condition of the ecosystem. These can be natural components such as nutrients or entirely anthropogenic components such as litter or biota removal/disturbance. Some stressors, such as toxicants, may have natural (e.g. particular metals) and anthropogenic (e.g. pesticides) aspects. In Queensland, the following "components of the environment" have been identified as major stressors important in our estuaries: * Aquatic sediments * Bacteria/pathogens * Biota removal/disturbance * Freshwater flow regime * Habitat removal/disturbance * Hydrodynamics * Litter * Nutrients * Organic matter * Pest species * pH * Toxicants Different components are affected by different human activities (pressures) and their change has differing impacts (biological responses). The basic principle is: for each key component there are human activities that cause a change to an actual pressure acting on a system which in turn cause a change to the physical-chemical state of the system. This physical-chemical change results in a corresponding impact on the biota of the waterway. We can monitor indicators for each of these elements which then help determine what is the "risk" of a waterway being affected by pressures and what the current condition of the waterway is. Therefore, links between human activities and biological condition can be closely examined and management activities determined. For further information on the estuarine assessment framework used here please contact Andrew Moss, Qld EPA; (07) 3896 9245).