It’s not a surprise that the wetlands in the Olympic Park were struck by pollution but it is disappointing. The way the drainage and sewer system was designed could have been more environmental. Road run-off goes directly to water bodies with no treatment. It appears Combined Sewer Overflows discharge to them as well. In addition there are increasing amounts of high density developments around the Park which puts pressure on sewers. London Waterkeeper is investigating the systemic reasons. 
We need –
1) To know if sewers overflow to these water bodies
2) To know if Thames Water is maintaining sewers adequately
3) Waste pipes from nearby developments investigated
4) Drainage from nearby construction sites checked
5) Any polluters prosecuted by the Environment Agency

A big reason why pollution keeps damaging parks across London is the lack of environmental information in public. When it comes to rivers, the authorities are letting us down. We need to be told when sewers overflow. With that information we can hold power to account and people can make informed choices. The need for our approach is borne out by events in the Olympic Park.

Sometimes it is hard to challenge the pollution because responsibilities are confused. In the Olympic Park one wetland pond is the responsibility of property development East Village. The larger pond that was contaminated comes under London Legacy with the Chobham Manor run-off going to it. Thames Water has responsibility for some of the sewers. The Environment Agency is the environmental law enforcer. Chair of London Waterkeeper, Dee O’Connell, reported the problem to the Environment Agency and Thames Water. A clean-up team was sent to the site. London Waterkeeper amplified the call to action. Dee’s experience of seeing the River Lea affected by different problems meant she was well prepared. Our tips for reporting pollution are here.

Our Drain Shame campaign highlights the under-investment in preventing pollution. In 2018, when Thames Water was developing its Business Plan for 20-25, it proposed only cleaning up 500 dirty drains. In London Alone there are more than 1,000. We asked people to put pressure on them and in April 2019 the Business Plan said it would tackle 750 polluting outfalls. Still not enough. We asked the regulators Ofwat and the Environment Agency to tell Thames Water to do more, but that didn’t happen. So we will see how well the authorities cope in the next 5 years.
The Zoological Society for London published this report that called for a 5x increase in efforts to tackle polluting drains. We will be watching. The under-investment also means that even when a problem drain is sorted, pollution re-occurs.
We won’t pretend the recent incident at the Olympic Park Wetlands is an isolated problem, the truth is that it has been happening for years. London Waterkeeper will protect this and other precious places across London.