Water quality profile of an urbanising catchment – Ningi Creek Catchment

摘要

BackgroundudContamination of waterways is becoming a critical issue, especially in areas undergoing rapid urban development. Faecal contamination of water resources is of critical importance specifically in relation to protection of public health. Additionally, increased pollutant loading into waterways can also cause significant environmental degradation. The Ningi Creek catchment in Caboolture Shire is a prime example of an area which is being subjected to increasing pressures due to changes in land use. Recent studies performed by the Department of Primary Industries (DPI) on the water in Ningi Creek, revealed high levels of faecal coliforms, indicating a serious faecal pollution problem. The catchment area of Ningi Creek contains a number of land uses, including forestry areas, farmland areas, aquaculture, rural-residential and residential developments serviced by on-site wastewater treatment systems. Any of these may cause contamination of the ground and surface water, particularly during rainfall events. ududProjectudThe research project was confined to the Ningi Creek catchment in Caboolture Shire, focusing specifically on the surface and groundwater along the Creek. The main focus of the research project involved three main objectives:ud1.To develop a water quality profile along the length of the Ningi Creek. This included the identification and assessment of faecal coliform levels and Lyngbya ‘trigger parameters’ which would enable the identification of land uses and regions within the catchment that contributes to pollutant loads.ud2.To identify ‘hot spots’ for faecal coliforms and Lyngbya ‘trigger contaminants’ in Ningi Creek, and the corresponding contaminant sources.ud3.To develop a critical point monitoring program for Ningi Creek catchment, to identify specific areas to be monitored in order to help safeguard the region’s aquatic resources.ududThe project adopted a holistic approach, identifying significant factors contributing to the pollution of Ningi Creek, rather than just the sources of faecal contamination and other pollutants. Essentially, it is intended that the knowledge generated through this project will contribute to the development of a Waterway Management Plan for the Ningi Creek Catchment. Whilst the source and impact of faecal coliforms on water quality in Ningi Creek with regard to the operation of oyster leases were the primary focus, useful knowledge was also created to address catchment management considerations in relation to the control of a selected number of ‘trigger contaminants’ for the cyanobacteria Lyngbya majuscula.ududOutcomesudThe summary of outcomes from the comprehensive study undertaken include:ud1.The development of a water quality profile for Ningi Creek to enable an overall evaluation of the catchment and the different land uses that may contribute to the pollutant loading; ud2.The identification of the various sources of faecal contamination in order to allow appropriate management strategies to be implemented to minimise faecal bacterial loading into Ningi Creek;ud3.The identification of sources of the trigger parameters which cause and sustain L. majuscula blooms in Ningi Creek; andud4.The development of a critical point monitoring program to enable the Caboolture Shire Council to monitor, manage and mitigate the pollutant inputs into Ningi Creek.ududThe key findings and recommendations from the study are discussed below.