Lake Trevallyn Algal Bloom monitoring records the presence and abundance of blue-green algae in Lake Trevallyn during the peak summer recreational period, to provide early warning mechanisms to water authorities and the public on when the lake is safe for use. Data is used to understand the key drivers influencing outbreaks and to propose management strategies.
The Lake Trevallyn Algal Bloom Monitoring Program coordinates water quality monitoring for Lake Trevallyn. Pathogen (enterococci) and blue-green algae (Dolichospermum circinale) assessments are completed weekly at the Trevallyn boat ramp and at the Blackstone Park beach. Water quality data (pH, electrical conductivity, turbidity, chlorophyll-a, Phycocyanin and water temperature) are collected 24/7 near the dam wall and water temperature is collected to a depth of 10m at the same location. The data is used to identify early warning signs of blue-green algal blooms, while providing a centralised data collection point for all stakeholders.
In low numbers, algae are a natural part of a water body. However, algae can occasionally grow very fast or ‘bloom’ and accumulate into dense visible patches at the surface of the water. In these conditions, algal blooms can become a serious public health and environmental problem in many waterways.
The blue-green algae (Dolichospermum circinale) was first discovered in Lake Trevallyn in bloom proportions in January 2007. Algal blooms can be driven by low water flows and high levels of available nutrients, such as phosphorous and nitrogen, which promote its growth. Contact with an algal bloom can potentially cause a number of human health problems including skin rashes, eye irritation, earaches, itchiness, swollen lips and other symptoms, and can also cause unpleasant taste and odour compounds in drinking water.
Data collection through monitoring is increasing our understanding of the bloom processes in Lake Trevallyn for future management of the lake – a key body of water for Launceston’s recreation and the storage of drinking water.
The Lake Trevallyn Algal Bloom Monitoring Program and Working Group was established following the 2007 algal bloom event, as a coordinated partnership approach to monitoring. Pathogen (enterococci) and blue-green algae (Dolichospermum circinale) assessments are coordinated weekly throughout summer at the Trevallyn boat ramp and at the Blackstone Park beach to measure water quality data and water temperature.
The first recorded bloom in Lake Trevallyn occurred in the summer of 2007. During 2008/09 summer a smaller bloom occurred over a two week period. Most years, blue green algal numbers increase towards the end of summer however no large visible blooms have been detected in Lake Trevallyn for a number of years.
Suitable nutrient concentrations for algal growth always seem to be present in Lake Trevallyn, however water flows are a major controlling factor of blue green algal blooms. High water flows during summer may prevent the blooms from becoming established, as seen in the 2009/2010 summer.
Algal blooms persist when water temperature continues to rise under the influence of high summer temperatures, promoting Dolichospermum circinale cell growth and surface concentration. Dolichospermum circinale cells detected in the monitoring program have, to date, all been found to be non-toxic.
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