Mary catchment water quality going down hill
THE WATER quality of the Mary River and related creeks is deteriorating, says researchers.
Volunteers for the Mary River Catchment Coordinating Committee (MRCCC) have spent the last 18 months collecting samples of water from different sections of the Mary River and connected creeks such as Tanyalba Ck, Gutchy Ck and Goora Ck.
In some places, the MRCCC has been able to collect more than a decade of samples and in others this is the first season on record.
"Now we've got more than one season of data and we get an idea of what the normal quality of water is for that area," Researcher Steve Burgess said.
"We give these sites an A, B, C grading, a bit like healthy waterways report card but our own, based on the physical and chemical quality."
The Mary River as a whole received a B grade, but the results show the water quality has deteriorated in the past five years.
Mr Burgess said the recent floods were the main cause of the worsening quality, but there had also been an impact from agriculture, especially in the creek systems.
"Over the last three years there have been problems with sediment and soil being carried down the river from the floods," he said.
"That is natural but the fact that we've got river banks which aren't as vegetated as they used to be means there's more erosion than what it might have done if the river banks had been in their natural states."
Some parts of the water system were in pristine condition, whereas others received fails on their report cards, such as Gutchy Ck.
According to the water quality guidelines, the oxygen percentage of the Mary river catchment should be between 85-100%- Gutchy Ck's oxygen level sits between 25 and 47%.
"Gutchy Ck is the one where we've got the most trouble with water quality," Steve said.
"So we want to know more about it, it's a significant creek for the critters and people who use it."
The data collected will be presented to the State and Federal Governments to better understand the Mary River's water quality, and improve the current guidelines.