The wellbeing of aquatic fauna in the Helena River, which originates on the Darling Scarp and flows into the upper Swan at Guildford, is being monitored by fish ecologists at The University of Western Australia's Albany-based Centre of Excellence in Natural Resource Management.
The fauna - which include iconic native WA freshwater species such as freshwater cobbler and a threatened species of freshwater mussel - live in permanent pools in the drying river which is part of a regulated catchment area that provides some of Kalgoorlie's drinking water via pipeline.
Assistant Professor Paul Close is working with the Swan River Trust to evaluate the effect of small-scale water releases on the health of animals in the pools. The pools, some of which are as big as an Olympic swimming pool, are becoming warmer and saltier as the summer wears on and there is also less oxygen available in the water for river fauna.
The summer water releases are managed by the Department of Water and Water Corporation, in conjunction with the Swan River Trust, and are aimed at keeping the pools topped up with fresh, cool water and maintaining adequate oxygen levels.
During winter months, water flows into the pools from small tributaries, but in summer there is no flow apart from the controlled releases.
"Summers are getting drier and the population is getting bigger, so there is a trade-off between the human demand for water and the need to maintain the river's ecology," Assistant Professor Close said.
"While WA native fish are quite resilient and used to dealing with highly variable conditions and extremes, there is a risk that even they will not be able to tolerate such low oxygen levels and increases in salinity and water temperatures.
"If we can learn more about the river's species and how the river functions, we will be in a better position to balance the needs of humans and that of the ecosystem."
A report on the outcomes of the investigation will be provided to the Swan River Trust later in the year and will provide guidance in managing future water releases.