Independent testing organised by residents has found high levels of metals and pesticides in a river thousands of people rely on for drinking water in western NSW.

The Dharriwaa Elders Group (DEG) in Walgett partnered with Charles Sturt University (CSU) to test for a number of different substances in the Namoi and Barwon Rivers.

DEG treasurer Rick Townsend said group members were concerned about the Namoi River's health after catching several fish with sores on their bodies recently.

"We believe that the water isn't safe to drink … and we are afraid [the fish] are not safe to eat," he said.

A preliminary summary of water quality findings, which is yet to be peer reviewed, indicated a number of metals and pesticides were found in the Namoi River.

The testing assessed the health of the river's ecosystem rather than the water's drinkability.

Council says drinking water is safe

Until last year, residents were exclusively drinking bore water due to the Namoi River running dry in 2018.

The river restarted supplying drinking water to about 7,000 people in the Walgett Shire last year, via a council-operated reverse osmosis plant.

However, the NSW Department of Climate Change, Energy, the Environment and Water have confirmed that due to workforce shortages, the plant is currently not in use, and the town is back on bore water. 

The Walgett Shire Council said the treated river water, and the bore water was safe to drink.

In a statement, council's general manager Megan Dixon said water utilities and infrastructure were within the local government's remit. 

"However, management of river water quality sits squarely with WaterNSW," she said.

"Councils have reason for concern about river water quality as they extract raw water from these rivers before it is treated for human consumption.

"Walgett Shire Council has established relationships with all government agencies and continuously advocate for support and improvements on behalf of the community."

Metal levels 'higher than expected'

CSU scientist Katie Doyle, from the team that analysed the lab results, said the river's water quality would need to be monitored into the future.

"The total [amounts of] phosphorus and nitrogen were reasonably high in the river system," Dr Doyle said.

"We also found a few metals in the water were higher than expected — aluminium and copper in particular."

The testing also found six different types of pesticides in the water.

The report noted three of the pesticides, atrazine, diuron, and a mixture of S and R-metolachlor, were banned in the European Union, but not Australia.

Dr Doyle said the fact the chemicals were found outside of spraying season was unusual.

Dr Doyle said she would not personally choose to drink water from the river but the results could not definitively indicate whether it was safe to drink.

Minister says WaterNSW not responsible

During Budget Estimates, Greens MLC Cate Faehrmann asked NSW Water Minister Rose Jackson about the water quality in Walgett.

Ms Jackson said she was not familiar with the research conducted by the DEG and CSU, but that river water testing was not the state government's responsibility. 

"It's not something that WaterNSW would do," she said.

"As the river operator, they are not really responsible for that.

Ms Jackson said the Walgett Shire Council was responsible for "the provision of drinking water, the testing of that drinking water [and] assurances that it is within drinking water guidelines".

DEG member Zoe Sands said the group felt it had to take matters into its own hands as it could not find any historical testing results.

"We are unhappy with the government's response to our requests about Walgett's water," she said.

"That is why we felt we had to do this water sampling work ourselves."