Thousands of fish were feared dead today after a suspected pollution leak into the canal network in Wolverhampton.
The alarm was raised after an orange-brown colour was spotted spreading through the water at Oxley Marina.
Soon after, dead fish were seen floating in the water, near the junction with the Shropshire Union and Staffordshire & Worcestershire canals. It is suspected that the pollution may have originated at the Severn Trent Water-owned Barnhurst Sewage Treatment Works.
An investigation into the source is ongoing.
In April 2009 about 50,000 fish were killed along a 30-mile stretch of the canal when ammonia leaked from the works into the water.
Severn Trent Water spokeswoman Sarah-Jayne O'Kane said: "We have informed the Environment Agency and have been investigating possible causes of this discharge."