River Torrens Water Quality Improvement Trial Summer 2011/2012

News Title:

2024 CLLMM Science Forum, Workshop held to improve outcomes in the Ecohydrological conceptual Models and Impact Pathway diagrams Project, 60 seconds with Prof Tom Raimondo, 60 seconds with the Goyder Chair, Jody Swirepik, Update on the Coorong, Lower Lakes and Murray Mouth (CLLMM) Research Centre, Outputs from National Drinking Water Forum in remote First Nations communities Released, Successful Launch of the Coorong, Lower Lakes and Murray Mouth (CLLMM) Research Centre, New Fact Sheet: Translating Yannarumi into Water Resource Risk Assessments, Thank you for all those who attended Science in The Pub!, Join us for the Annual #WORLDWATERRUN from 18-24th March!, Science in the Pub presents "The Coorong, Lower Lakes and Murray Mouth: A journey through droughts and floods.", Join us to Launch the New CLLMM Research Centre, New Project: Analysis of changes in high-intensity rainfall events in South Australia, Goyder Institute 2023 Annual Report Reflects on a Busy Year, New Project: Measuring the impact of Ground Water extractions on Mound Springs in Northern South Australia, CLLMM Research Centre announces a new location in the region, Goyder Institute for Water Research announces new Chair, New Coorong, Lower Lakes and Murray Mouth Research Centre has hit the ground running. , New Project Aims to Understand the Environmental Response of the Coorong to the 2022-2023 River Murray Flood Event, Another New Member of Staff Joins the Goyder Institute, Goyder Institute welcomes another new staff member to the team, New Goyder Institute CLLMM Research Centre Participates in Collaborative Effort to Assist with Environmental DNA Sampling for Threatened Species, Delivering a Better Understanding of Water and Ecological interactions in the Braemar, Stuart Shelf and Northern Eyre Peninsula regions for Sustainable Development, Goyder Institute announces new Director, Goyder Institute welcomes three new staff to the team, Are you the Goyder Institute’s new Communications and Engagement Coordinator?, One Basin CRC holds its first annual event, Messages from the Working together for better drinking water in the bush forum warmly received by Federal Minister Plibersek, Research to continue on environmental impact of recent floods, Help us drive sustainable, innovative and integrated water management, Farewell to Daniel Pierce, Introducing the Goyder Institute's 2023-2026 Strategic Plan, Working together for better drinking water for bush communities, Coorong Research Hub to embark on program to address the effects of climate change, Goyder Institute welcomes two new staff to the team, Supporting climate change resilience in the Coorong, New website goes live, Institute research on show at Healthy Coorong Healthy Basin Science Forum, Goyder Institute takes home back-to-back national R&D excellence awards, Increased flushing vital to Coorong’s long-term health, Ruppia restoration strategy released for southern Coorong, Institute scientists head to River Murray to study environmental impacts of flood, Your chance to contribute to the development of a Resilient Water Future for Greater Adelaide, Institute embarks on a strategic planning refresh, Team Goyder is off and running again for World Water Day, Goyder Institute extended to 2026, New research report reveals pathway to keeping Adelaide’s liveable city status, Chair Prof Barry Hart releases Institute's 2022 Annual Report, A year in review and farewell from our Director, Goyder Institute’s Healthy Coorong, Healthy Basin Research Project wins R&D Excellence Award, How feasible is a water resource rating system for South Australia?, New research project in the South-East kicks off with aerial survey of groundwater, Australian Government announces new Research Hub of the Goyder Institute to support the Coorong, Lower Lakes and Murray Mouth region, Australian Government announces new Research Hub of the Goyder Institute to support the Coorong, Lower Lakes and Murray Mouth region, Chair announcement: Goyder Institute leadership update, Policy changes are needed to better protect environmental water from climate change in the Murray-Darling Basin, Join us as the Goyder Institute prepares to Sweat4Soap once more, Limestone Coast Landscape Board partners with the Goyder Institute to investigate adaptation of the South-East drainage network, New videos showcase research to inform the management of the Coorong, One Basin CRC takes initial steps towards shaping its research program, The South Australian Government and Goyder Institute partner to establish a Water Ambassador, One Basin CRC advances towards establishment with key roles formed, How feasible is land-based aquaculture in South Australia?, Major step towards Institute’s goals achieved as Coorong research concludes, Goyder Institute wins national award for Research Excellence, One Basin CRC to drive a sustainable future for the Murray-Darling Basin, New research project established to explore the feasibility of a water resource rating system, Healthy Coorong, Healthy Basin Program fieldwork wraps up, Goyder Institute research supports $10 million investment to improve shorebird habitat, Floods and recent climate projections highlight the importance of ongoing water reform, Water Resources Conference at the World Expo in Dubai identifies new international partnership opportunities, ONE Basin Cooperative Research Centre takes another important step forward, New project established to inform future urban water management options for Adelaide, In Focus: Research providing knowledge to identify climate adaptation pathways for the Coorong and Lower Lakes region, Running for World Wetlands Day (2 February 2022), 2022 shaping up to be an important year, Great progress towards our third term goals as 2021 draws to a close, In Focus: Research providing knowledge to restore a functioning Coorong food web, Welcome news for the ONE Basin Cooperative Research Centre, Impact of second-term projects continue to ‘flow’, Goyder Institute announced as winner of Australian Water Association’s SA Branch R&D award, The Goyder Institute’s new Interim Director looks to an exciting year ahead, In Focus: Research providing knowledge to maintain viable waterbird populations in the Coorong South Lagoon, Goyder Institute team surpasses its #Sweat4Soap target, Call for participation – water resources conference at World Expo in Dubai, Independent evaluation highlights success of Institute’s second term, Goyder Institute team commits to #Sweat4Soap, In Focus: Research providing knowledge to inform the future management of aquatic plants and algae in the Coorong South Lagoon, In Focus: Research providing knowledge to inform the future management of nutrient levels in the Coorong South Lagoon, Goyder Institute partners in the ONE Basin CRC rebid, IPCC 2021 Report on Climate Change emphasises need for the Goyder Institute to continue to support climate mitigation and adaptation, Goyder Institute showcases its Strategic Plan, Goyder Institute unveils new branding, The Sustainable Development Goals and the Goyder Institute for Water Research, Coorong scientific research project crosses halfway mark, Translating Ngarrindjeri Yannarumi into water resource risk assessments, Reducing fine sediment loads into Adelaide’s coastal waters, Project Coorong’s Science Forum resources now available, From South Lagoon to Siberia: tracking Coorong waterbirds via satellite, Interim management updates, New South Australian Government Climate Change Action Plan provides framework for future research of the Goyder Institute, Institute welcomes new Research Program Manager, ONE Basin CRC bid Stage 2 progresses to final stages, Congratulations Prof McKay – winner Premier’s Water Professional of the Year Award, Second term finishes strong – a year in review from the Director, ANNOUNCEMENT: Goyder Institute welcomes a new Chair and Management Board and Research Advisory Committee representatives, Citizen Science: a key part of the Goyder Institute’s involvement in the HCHB program, Finding ancient water in the outback – new research to support remote communities and enterprises, Vale Professor Peter Teasdale, Goyder Institute partners with the Australian and South Australian governments to restore a wetland of international importance - the Coorong’s South Lagoon, ANNOUNCEMENT: Goyder Institute partners establish the third term of the Institute, ONE Basin CRC bid continues to take shape to address the needs of basin governments, industries and communities, Flow on effects – new tools to support the integrated management of river flows and floodplain infrastructure along the River Murray, Advancing integrated management of Spencer Gulf for economic, social and ecological outcomes, Sea grass communities in Gulf St Vincent to benefit from new stormwater management intervention project, ICE WaRM ceases operations after 15 years of advancing excellence in water leadership across the globe, Agricultural technologies in South Australia survey, Investigations underway to help restore the Coorong, Expert panel recommendations inform changes to groundwater management in the Lower Limestone Coast, ONE Basin CRC bid gains momentum, R&D plan charts course for the year ahead, New research papers outline innovative approaches for water exploration and palaeovalley evolution, Call for expressions of interest – ONE Basin Cooperative Research Centre, A year in review from the Director, Research establishes proof of concept for blue carbon benefits from tidal reconnection of coastal wetlands, New research identifies the importance of healthy coastal habitats for combating climate change, New tools to help growers sustainably expand production in the Northern Adelaide Corridor, New research advances blue carbon opportunities in South Australia, Goyder Institute joins Smart Water Mission to New Zealand, Women changing the future of water, State Government seeks community feedback on Healthy Coorong, Healthy Basin Action Plan, Water managers now able to predict potential foodweb changes associated with floodplain inundation, Women in Water -- visibility matters, SA's droughts are getting worse -- new published research informed by Institute's SA Climate Ready data, G-FLOWS project enters final stages -- characterising the dimensions of a newly discovered paleochannel in the APY Lands, Goyder Institute for Water Research awarded Minister's Award for Excellence, Goyder Institute projects recognised for informing international best practice approaches to Indigenous engagement, Congratulations to Darryl Day -- Water Professional of the Year, Goyder Institute releases findings of independent review of the science underpinning water allocation reductions in the South East, Carbon offsets research to support the State Carbon Sequestration Strategy

Project Partners:

The University of Adelaide and SARDI

Research Theme:

N/A

Status:

Project Overview

The management of rivers, lakes and reservoirs is a difficult task which demands considerable effort to restore deteriorating catchments, water habitats and water quality. The Torrens Lake, in Adelaide South Australia, has similar problems to many lakes worldwide including catchment clearing, nutrient focussing, flow regulation, water extraction for irrigation and cyanobacterial blooms.

It is unlikely that any management strategy will reduce cyanobacterial numbers to zero and therefore the most realistic strategy would be one that controls the cyanobacterial population below the guideline concentration for recreational exposure. Artificial destratification is likely to be ineffective at controlling cyanobacteria in the Torrens, as the system is shallow and mixing inefficient. Nutrient control will constrain cyanobacterial biomass but the Torrens catchment delivers high loads of nutrients to the lake and it will be decades before control measures limit growth to the desired thresholds.

The aim of this study was to investigate whether a controlled upstream release of water could effectively dilute the population and control cyanobacteria numbers below a threshold. For a growth rate of 0.4/day, which is a typical exponential growth rate of cyanobacteria in the Torrens Lake, it can be concluded that a diluting flow of at least 10% per day would be required to have noticeable impact on the cyanobacteria population. With a starting cell concentration of 100 cells/mL, a growth rate of 0.4/day and a diluting flow of 10%, the cell concentration after 20 days would be 74,420 cells/mL, which is below the critical threshold for cell numbers.

Progress Update and Key Findings

A trial was conducted in the summer of 2011/12. Flows were released from Hope Valley Reservoir in response to the level of cyanobacteria present in the Torrens Lake with the aim of keeping cyanobacterial numbers in check and avoiding lake closure. During a period when upstream water was unavailable the cyanobacteria grew exponentially and the population exceeded the threshold concentration. Under similar meteorological conditions later in summer the population was maintained by a combination of controlled amenity flows and rain event inflows.

Project Impacts

The study concluded that:

  • The simple model of growth and dilution is a reasonable predictor of biomass change at low cell density, however population decrease is underestimated by the predictive model.
  • Dilution is possibly greater than predicted because high concentrations of cells near the surface are washed out of the lake with the overflow of water over the weir.
  • Nutrient or light limitation possibly contributed to the observed decrease in growth rates; nutrient limitation as the population expands and consumes the available resources during periods of rapid growth, and light limitation following rain events as coloured material is washed into the lake.
  • The results of the trial suggest that if dilution flows are released early enough, the size of the cyanobacterial population can be controlled. However, there is a reliance on rain events to flush the system and dilute the resident cyanobacterial population. On average, the flow return interval analysis suggests that rain events occur frequently enough in summer for this strategy to be effective. However, in a variable climate like that observed in Adelaide, there may be incidences of very long periods between significant rainfall events. This may reduce the confidence in rain events to reset the population.
  • The dilution flow was not observed to have any impact on the freshwater fish community.

Research Outputs

ELCOM Hydrodynamic Model

River Torrens Water Quality Improvement Trial - Summer 2011/12

Project News