Lake Jindabyne — a water quality project

Phil Boreham and Lee Bowling - Snowy Mountains Authority and Department of Water Resources , 04 October, 1990

Lake Jindabyne is a major water storage in the Snowy Mountains region of NSW. The darn was completed in 1967. Concern over the biological state of the lake was expressed during the late 1970’s when excessive weed growth appeared in shallow waters during summer months. The Operations Planning Division, SMHEA, initiated a study during 1980 – 86. This study revealed an apparent high phosphorus loading and retention rate in lake sediments and low dissolved oxygen concentrations within lake waters.

The fact that limited information was available concerning lake water characteristics, coupled with the prospect of its deteriorating quality, prompted the SMHEA in cooperation with the NSW Department of Water Resources to start further investigation.

A preliminary study began of the lake in February 1989 utilizing a Yeo-Kal Submersible Data Logger and a Ruttner Grab Sampler. Interpretation of nutrient and oxygen data gathered showed the lake to be in a well advanced Mesotrophic condition. On the threshold of change, a small increase in nutrients may possibly result in a eutrophic condition. Blue-greens or Cyanobacteria, indicative of this, have so far only rarely been encountered in algal samples.

A comprehensive three year study has commenced. Due for completion in 1993 a routine sampling programme is being conducted by SMHEA Hydrometric staff under the guidance of the Water Quality Unit, NSW Department of Water Resources. Sampling encompasses the lake, major inflow sources including streams, runoff from urban and agricultural areas and outflow points from the lake comprising pumping and riparian releases.

The aim of the project is the establishment of a basis of information with which to determine future changes in lake water quality. This basis will include the estimation of a nutrient budget for Lake Jindabyne.

Changing practice and priorities in the catchment area provide the motivation for this study. Increasingly closer settlement patterns, pressure from tourist developments , ski resorts and agricultural pursuits need to be considered with regard to this study, the objective of which is to apportion total nutrient loading to the sources in line with a Total Catchment Management concept.