The ancient sewer system beneath the city of London could not handle heavy rains on Tuesday and disgorged hundreds of thousands of tons of raw sewage into the Thames River, the Environment Agency said. Thousands of fish were killed as the river turned toxic overnight.
The spill followed violent storms in the capital, which saw 42 millimeters (1.65 inches) of rain fall in just one hour. The combined sewer system, which carries both sewage and storm overflow, was completely overwhelmed.
"We deeply regret the loss of fish in the Thames last night," said Robin Clarke, director of Waste Water Operations at Thames Water. "The scale of the fish loss last night was very rare - a very unfortunate side effect of the exceptionally heavy rainfall."
Thames Water helps fish to survive storm discharges to the Thames River by deploying two "Bubbler" vessels, which pump extra oxygen into the river.
The River Thames was polluted with sewage overflow after Tuesday's storm. (Photo courtesy FreeFoto)
Clarke said Thames Water is working with the Environment Agency to minimize the impact of the pollution that occurred following the storm. Within the historical constraints of system, the safety valve of letting the dilute sewage go to the river during storms, though regrettable, Clarke said, is preferable to the flooding backing up out of the sewers into London's streets.
"Despite events such as last night, the Thames remains one of the cleanest metropolitan rivers in the world, said Clarke.
"This is directly linked to Thames Water's £1 billion investment at sewage treatment works, which has paved the way for wildlife to return the river, which was biologically dead for many years," he said.
Climate change and population growth accentuate the need to focus investment on replacing Victorian water mains in London and reducing the risk of sewer flooding to customers properties, Clarke explained.
By 2016 London is expected to have 800,000 new residents, the equivalent of the current population of Leeds.
Thames Water has been in close contact with the Department of Environment, Food and Rural Affairs (DEFRA) on the issue of storm discharges to the Thames Tideway.
One option under consideration is a new £2 to 3 billion tunnel to accommodate the storm flows.
Any investment to tackle the problem would need to be funded through the Office of Water Services Price Review process.
Flooding rains Tuesday night mixed with sewage, overflowed into the river. (Photo courtesy FreeFoto)
Coincidentally, today the Office of Water Services (Ofwat) issued its long awaited determinations of price limits for the water and sewerage companies in England and Wales from April 2005 to March 2010.
Under the draft determination, released for public comment, the average household bill would increase by 13 percent over the five year period.
The agency recommends that price limits would rise by 3.1 percent a year for five years, before inflation, half the increase sought by water companies.
In addition, there would be higher average increase of 7.6 percent in 2005 to reflect the build-up of companies’ costs, tailing off to 1.2 percent in 2009. The companies sought 13.4 percent in 2005.
Director General Philip Fletcher said the price increases would provide for the safeguard of all essential services as well as a bigger program to maintain pipes, sewers and treatment works for the future.
Safe, reliable drinking water would be paid for, including more improvements in water quality and security of supply.
The increase would cover a "major investment" in protecting and improving rivers and coastal waters.
In addition, 8,200 more households would be safeguarded against the risk of regular sewer flooding in their homes. By 2010, the proportion of properties at risk would reduce to 0.02 percent of households.
Fletcher said, "We judge that an increase in price limits is essential to maintain the progress which has already been achieved and to make the further advances required."
At Thames Water, Clarke said the company's biggest priority for the price review is to tackle leakage and reduce sewer flooding to customers' properties. But, he said the company is "ready, willing and able to put in place any action plan, once its financing is signed off by Government and Ofwat."
