7: Management Response

7.1 Introduction

The Authority is responsible for the management of the National Capital's Lake Burley Griffin to ensure its sustainable use and to protect and enhance its water quality.

This section covers:

7.2 Recommended Benchmark Values for Key Water Quality Indicators

The recommended benchmarks for water quality in Lake Burley Griffin are as follows:

Environmental Values Benchmark Values
Ornamental water
  • Turbidity values of 60 NTU in East Basin, and
    30 NTU in West Lake.
  • Suspended solids values of 50 mg/L in East Basin, and 25 mg/L in West Lake
Protection of freshwater aquatic system
  • Turbidity values of 60 NTU in East Basin and 30 NTU in West Lake.
  • Suspended solids values of 50 mg/L in East Basin and 25 mg/L in West Lake.
  • Total phosphorus concentration of 0.1 mg/L.
  • Total nitrogen concentrations of 1.6 mg/L in East Basin and 1.2 mg/L in West Lake.
  • Ammonia concentration of 0.1 mg/L.
  • Algal value of 5,000 cells/mL.
  • Chlorophyll-a concentration of 30 μg/L.
  • Conductivity of 500 μS/cm.
  • pH range of 6.5-9.0.
  • Metal values as specified by ANZECC/ARMCANZ (2000).

Recreational water

  • Bacterial quality as specified by ANZECC/ARMCANZ (2000) using absolute numbers.
Irrigation water for parks and gardens
  • Bacterial quality as specified by
    ANZECC/ARMCANZ (2000).

Benchmark values are provided only as a guide. The values for East Basin can be used generally for the Eastern sections of the Lake (i.e Central Basin) whereas the values for the West Basin can be used generally for the western sections of the Lake (i.e West Lake to Scrivener Dam).

Although the development of a benchmark value in this Water Quality Management Plan (WQMP) generally follows the Australia-wide National Water Quality Management Strategy procedures, it nevertheless includes some local adaptations.

Instead of defining water quality objectives based on 80th percentile values, this WQMP proposes water quality benchmark values. These benchmark values are close to, but not necessarily exactly, at the 80th percentile values for each data set. The benchmark values as used in this WQMP are based on a combination of statistical analysis and scientific judgement.

The benchmark values will be reviewed from time to time, as new information and research on water quality becomes availabe.