The Msunduzi municipality's environmental health unit on Tuesday warned communities in and around Pietermaritzburg to stay away from rivers affected by last week's oil and caustic acid spill.

Despite earlier warnings, there were reports of communities retrieving dead fish from the contaminated Baynespruit and Duzi rivers to sell to unsuspecting customers.

"The message is still very clear that the river system is still a no-go area. The public is warned to refrain from utilising the water for various purposes, including drinking, washing of dishes and clothing, irrigation, retrieving dead fish, swimming, fishing and canoeing," said the unit.

"However, water from the municipality’s supply is absolutely safe for use, as it is purified at the Midmar and DV Harris water treatment works."

Vegetable oil and caustic acid from the Willowton Group's oil factory spilled into the Baynespruit stream following an accident at its facility on August 13, polluting the water.

The pollution reached the Umsunduzi River, into which the Baynespruit flows. The pollution also reportedly affected the Darvill wastewater treatment plant, the main treatment plant for Pietermaritzburg.

The Willowton Group has embarked on clean-up operations, said the unit.

"Most of the solids on the Baynespruit and Duzi rivers are now recovered and the pH levels have stabilised. Due to the fish kill, the clean-up crews are working from Pietermaritzburg to Inanda Dam to recover the fish. The colour of the water has also normalised.

"However, aquatic organisms have been severely impacted and environmental studies are being conducted regarding the extent of the damage. The visible foam, being a separation of the oil fats, has almost totally been contained and removed."

The municipality will be auditing Willowton's premises to determine if the company has been adhering to legislation.

"The department of water and sanitation had issued the directive in terms of the National Water Act to the Willowton Group on August 16. This instructs them to stop and contain the spillage, as well as implement clean-up and rehabilitation operations. Continuous reporting on progress must be submitted to the department.

"Legal action will be instituted for noncompliance of this directive."