Ecosystem Health Monitoring Program    2011 Report Card Results   2011 Key Messages

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 2011 Report Card key messages

The 2011 Report Card results provide insight into the health of our waterways and Moreton Bay, using data collected before and after the January 2011 flood.

Most regions in South East Queensland experienced higher than average rainfall from July 2010 through to March 2011. Intense rainfall during December and January, especially in the northern and western catchments, led to the largest regional flood event since 1974.

The 2011 Report Card grades are more positive than expected, considering the magnitude of the flood. However, the grades do not necessarily reflect the full impact of the flood on waterway health because half of the data for the reporting year was collected before the flood. In addition, the EHMP is designed to monitor long-term trends in ecosystem health; therefore, short-term impacts of the flood are not reflected in the grades. To understand the full impact of the flood, ongoing monitoring is being undertaken by Healthy Waterways members to assess the short, medium and long-term effects.

The 2011 Report Card shows some freshwater streams and estuaries improved in grade, reflecting the positive influence of high water flows. However, Moreton Bay experienced the full force of the flood, which moved a significant amount of sediment and nutrients from the catchments out into the bay.

The impact of major rainfall events on waterway health highlights the need to build the resilience of our catchments. We must prepare our catchments for rainfall events by managing erosion, stabilising creek channels, rehabilitating riparian (or riverbank) areas, investing in good agricultural practices and sustainably managing urban water.

Moreton Bay
The overall grade for Moreton Bay declined from a C to C-. This is the third consecutive year that Moreton Bay has fallen below its long-term average of a B grade.

Moreton Bay has been struggling to recover since the drought breaking rain in 2009 caused increased sediment and nutrients to enter the bay from degraded catchments. As a result, the overall grade for Moreton Bay in 2009 declined from a B- to a D.

Most of the pollution transported by the flood was deposited on the western side of the bay, north of the Brisbane River, causing a grade decline in Bramble Bay (D+ to D-). Other zones impacted by the flood plume also declined in grade including Eastern Bay (B to B-) and Eastern Banks (A to A-).

Some zones in Moreton Bay that were not significantly impacted by the flood plume improved in grade. For example, Pumicestone Passage had the greatest improvement (D+ to C+) reversing its decline in 2010 (C+ to D+).

Freshwater
All freshwater streams either improved in grade or remained the same, except for declines in Mid Brisbane (C to D-) and Nerang (B+ to B). As a result, some freshwater streams received their highest grade since monitoring began in 2000. Higher water levels have improved fish migration, resulting in greater numbers of native species in some streams. The Lower Brisbane, Oxley and Redland catchments remained a fail (F), despite improvements in most indicators. For 12 of the 19 catchments, there were improvements in all indicators, except for the nutrient cycling indicator which declined.

Estuaries
The Report Card grades for 14 of the 18 estuaries either improved or stayed the same. The flood was large enough to flush pollutants out of many estuaries. Noosa continued to receive the highest ecosystem health grade (B+) and the greatest improvements occurred in Coomera (C+ to B) and Currumbin (C to B-). The grades for Maroochy, Mooloolah, Tingalpa and Pimpama estuaries declined. The Oxley, Bremer, Logan and Albert estuaries continued to fail, despite overall improvements in most indicators.

Flood impacts: the good and the bad

Native fish found for the first time in 70 years
High river flows during 2010–11 enabled greater fish migrations. As a result, a freshwater fish species that scientists believed was locally extinct, Cox’s Gudgeon, has been found in the Brisbane River. There has been no record of the species since 1941 when a specimen was sent to the Queensland Museum. The species was found at many sites along the Brisbane River and Sunshine Coast. This highlights the positive influence a flood can have on the survival of native fish species.

Moreton Bay mud layer doubles
The millions of tonnes of sediment that entered Moreton Bay during the flood have now settled on the floor of the bay, causing the existing mud layer to almost double in size to approximately 100 km2.

The impacts of this mud will continue to be seen in the summer months when winds and warmer weather re-suspend the sediment, increasing turbidity, nutrients and algal blooms. This may result in a reduction of food availability for turtles and dugongs due to loss of seagrass.

Waterway health monitoring in the future - developing a broader monitoring framework
The January 2011 flood highlighted the need to monitor waterways for organisms (pathogens) that may affect human health. Healthy Waterways is working with our members to develop a Human Health Risk Monitoring Program. The program will identify potential waterway health risks, allowing the community to make informed decisions about using waterways for recreation.

This program will form part of a broader Monitoring and Evaluation Framework currently being developed by Healthy Waterways to address regional monitoring needs.