Residents in west London have expressed alarm over raw sewage entering the local canal system, with dead animals reportedly found washed up.
Addressing local councillors during a meeting of the Brentford and Syon Area Forum on Monday, Paul Keane, general manager at Brentford Community Boat House, said that this summer's “epidemic of heat” had exacerbated the situation.
The dead animals, whose specific species were not detailed, were mostly seen around the Brentford Lock Basin, where the Grand Union Canal passes through Brentford prior to joining the River Thames.
His comments came after concerned resident Peter Hughes told the forum that sewage was flowing into areas used for water sports.
The problem is believed to stem partly from misconnected plumbing in housing developments, where waste pipes are mistakenly directed into surface water drains rather than sewers, discharging untreated sewage into waterways.
Mr Hughes said: “The big fly in the ointment is sewage coming into the canal. That gets worse in the summer when the water is moving slowly, and some of that is historic, but also a contemporary mis-directing of sewage into storm drains.”
The resident said that, whilst he did not believe the pollution was the fault of Hounslow Council, it was an issue that needed to be addressed if the local authority wanted to encourage the water to be used for activities.
He added: “The water has to be hygienic, and there are times when it simply isn’t. It’s a very difficult issue, but it needs an overall strategy.”
Councillor Katherine Dunne said in reply: “There is some cross-borough working, particularly on that issue. There’s a River Brent catchment area group, and we know that officers in Ealing and Brent are looking closely at the issue of misconnections. But you’re right, it originates in those boroughs and then comes down into ours.”
In August, nine miles away in Ruislip, a resident spotted dead fish washing up on the shore of the Lido. This was determined to be caused by algal bloom, which caused a drop in oxygen levels in the water.
It is understood that hot weather exacerbated the conditions in Ruislip Lido that led to the deaths of fish with low oxygen levels.
Mr Keane, a former elite rower, told the forum that dead animals were discovered in the canal this summer, with local campaigners having to clear up the site.
The deceased animals were reportedly found to have E. coli and botulism. Botulism in aquatic animals is caused by ingesting toxins which thrive in warm shallow water. He said that the main area dead wildlife was discovered was around the Brentford Lock Basin.
He argued that the second section of water within the locks around Boston Manor Park is the most stagnant.
Stagnant warm water acts as a biological incubator that rapidly accelerates the growth of E-coli whilst simultaneously creating the conditions required for botulism outbreaks.
Botulism can only grow in environments with very low oxygen, conditions that stagnant warm water helps to create.
As water temperatures rise, the physical capacity of water to hold dissolved oxygen drops dramatically. The lack of movement in the water prevents oxygen from mixing into the water from the air. Coupled with E-coli, animals eventually die from both diseases.
Mr Keane told councillors that before hosting water sports events, the Canal and River Trust — the charity responsible for looking after historic waterways across England and Wales — conducts water tests, and has found that the water is “generally quite clean”.
Committee chair, Cllr Dan Bowring, urged those living in the Brentford West ward to contact their local representatives if they had concerns about the state of the canal.
