FARMERS along the Williams River near Clarence Town are concerned the waterway's health is deteriorating, with a potentially toxic algae "red alert" warning issued for the Seaham Weir Pool.
Janelle Spearpoint, who operates beef cattle business Greswick Angus, said she was surprised to find evidence of blue-green algae in a stretch of the river by her farm on the weekend.
"It's absolutely horrific," Mrs Spearpoint said. "At this time of the year, we should not be having algal blooms. It's extraordinary."
The state government organisation WaterNSW has posted on its website a "red alert" warning for high algal levels. A sample along this reach of the Williams River was last taken on May 12.
According to the website, "red alert" levels represent bloom conditions. The blooms should be considered toxic to humans and animals, and the water should not be used for drinking without treatment, stock watering, or for recreation.
"It's going to affect livelihoods that rely on the Williams River, because we use it for stock watering," said Janelle Spearpoint.
The beef cattle producer said she had to continue drawing water from the river for her stock "because there's no other option".
"Are they [government authorities] going to truck water in for the cattle?," she asked.
Yet the water users' concerns are not just for their stock. They are also worried about the implications downstream, as the weir pool is a major link in Newcastle's drinking water supply.
Hunter Water has said about half of the water in Grahamstown Dam is pumped from the Williams River at the Seaham Weir Pool.
"I think Newcastle residents should be made aware of the condition of the weir pool," Mrs Spearpoint said. "It's getting worse and worse."
In a statement, Hunter Water said what it supplied "remains safe to drink".
"We want to reassure our customers and our community that safe drinking water is our top priority," it said.
Digby Rayward, the President of the Williams River Care Association, said blue-green algae was just one environmental problem. In recent months, sections of the river had been clogged with a weed called hornwort.
"The blue-green algae and the hornwort are signs of a sick river," Mr Rayward said.
The association has been lobbying local and state governments for years, seeking action to be taken to improve the river health. One main issue has been the erosion of the river's banks.
Association members said algal outbreaks were occurring more frequently.
"This is why action needs to happen now," Mrs Spearpoint said.
Mr Rayward said he believed one of the major reasons for the outbreaks was the high levels of nutrients ending up in the river.
"Phosphorus and nitrogen levels must be at an all time high," he said, adding that the nutrient issue has been accumulating each year.
"The nutrient load is now at a critically high level, and we want to know what the plan is to reduce it."
Hunter Water said in its statement it was concerned about the long-term deterioration in water quality as a result of erosion.
The organisation said it was "working with other agencies and stakeholders to put in place a solution".
"Hunter Water continues to hold concerns that a failure to adequately address erosion in the Seaham Weir Pool would significantly increase the long term cost of producing drinking water at Grahamstown Water Treatment Plant," the corporation's statement said.
A spokesman for WaterNSW said there were currently six "red alert" sites for high algal levels across the state.
While outbreaks were more unusual in cooler weather, he said, they had been more prevalent after the drought conditions and lower water flows.
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