PETER Weatherly of the Avon Valley Environmental Society tested the water quality of the Avon River last Wednesday morning.
He said the water is currently healthy.
"It is nearly always healthy after good rain after a week or so has passed," he said.
"When the water first comes down it is usually a bit dirty because it picks up all the debris from the farms and the bottom of the river, but after a week it settles down nicely – especially with the good rains we have had."
Compared to the same time last year, Mr Weatherly said the river is noticeably better.
"It wasn't even running this time last year," he said.
"We have had a really good rain year and it shows in the health of the river."
He does not think future test results will change much.
"I think it will stay roughly at the level it is now with good levels of oxygen and pH," he said.
"The oxygen levels depend on lots of other things but it will cycle through the year.
"In summer it will go down, and in winter it will go up – but it's never gone so bad that it is toxic to everything."
When asked for his opinion on what could be done to improve the river, Mr Weatherly said it was a difficult question to answer.
"But number one would be to try and re-vegetate all of the sides of the river right out into the Wheatbelt," he said.
"It would be very expensive, but if it was doable it would make a big difference."
On the topic of Northam's remaining eight white swans, Mr Weatherly said he thinks there is too much inbreeding.
"I don't really know why those three cygnets died," he said.
"I can't think there's anything wrong with the river water or the health of the environment because all the other birds are thriving.
"There is something else, and it could well be the genetic base they are working from is simply not diverse enough.”