The Cabbage Tree estuary received an “F” in the 2009 Report Card, a drop in grade from the previous year (“D”).  Despite a reduction of nutrient loads discharged into the estuary because of upgrades to the Sandgate WWTP, nitrogen and phosphorus concentrations remain high and non-compliant with QWQ guidelines.  However, in 2008/2009, the median TP concentrations were the lowest measured since the EHMP began.  Turbidity also continued to be high and DO low within this system.  However, the reduction in Report Grade was primarily due to increased phytoplankton abundance, with Chl-a only 32% compliant with QWQ guidelines (compared with 84% the previous year).

Some of the water quality problems with this estuary occur because it is small relative to other estuaries that receive discharges from WWTPs and it is flushed by relatively poor quality water from Bramble Bay. Therefore, it is less able to process the nutrient loads discharged into it than the larger estuaries.  Cabbage Tree creek retains 59% unmodified habitat along its estuarine riparian zone.

Abbreviations glossary | Indicators and methods

ECOSYSTEM HEALTH INDEX (EHI)

The EHI is a measure of the proportion of a reporting zone that complied with the water quality objectives for key indicators monitored as part of the Ecosystem Health Monitoring Program. The water quality objectives are defined in the South East Queensland Regional Water Quality Management Strategy (2001).

• EHI 1 = 100% of area complies with the environmental objectives.
• EHI 0 = 0% of the area complies with the environmental objectives.

BIOLOGICAL HEALTH RATING (BHR)

The Partnership's Scientific Expert Panel has endorsed a change to the BHR in 2006-07 which increase the BHR from 20% to 30% of the Report Card Grade.

The reason for the change is the implementation of the Riparian Assessment Program (RAP) which will comprise 15% of the total grade (half of the BHR). The other BHR indicators will make up the last 15%

The data from the riparian assessment is available as PDF document.