The Dighty Burn is at the centre of a pollution scare after oil was found in the popular Dundee waterway.
The Scottish Environment Protection Agency is investigating the leakage into the burn in the north-east of the city.
The oil is believed to have come from a surface water drain upsteam of the road bridge at Baldovie that discharges directly into the burn.
It has spread down to the mouth of the burn at the Milton Bridge in Monifieth, and is causing an environmental concern.
The Dighty has benefited from comprehensive upgrades in wastewater treatment along its course. It is now a habitat for wildlife with herons and fish often seen along its route.
Scottish Water has placed a boom on the water west of Baldovie to contain the pollution, but the oil has been seen on the surface as far as Panmurefield.
A SEPA spokesman said: “We are aware of an incident of oil pollution on the Dighty Water close to Dundee and an investigation is under way to assess the environmental impact of the oil on the watercourse.
“From initial investigations, the oil has originated from a surface water drain which discharges directly into the Dighty Water.
“Scottish Water has been alerted to the incident and SEPA have been working closely with their officers to identify the source of the oil and put in place measures to ensure the oil is contained and absorbed, to reduce the impact on the ecology of the watercourse.”
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