Richmond MP Sarah Olney is demanding scrutiny of a controversial plan by Thames Water to take millions of litre of water from the Thames and replace it with treated sewage.

Nub News revealed the proposals this week and they have been met with horror by green organisations and the river clean-up campaigner Feargal Sharkey.

They have also provoked calls for the Environment Agency (EA) to step and block the plan.

Miss Olney said she had not been alerted to the proposal by Thames Water and she is urging residents to contribute to a public consultation exercise.

Thames Water is planning to hold an event at the Old Town Hall in Richmond on Monday afternoon to allow residents to ask about the proposals.

The plans would see up to 150 million litres of water a day abstracted from the Thames near Teddington, which would be transferred by pipeline and tunnel beneath the capital to east London.

The water removed from the Thames would be replaced by highly treated effluent from Mogden Sewage Works via a new 15km pipeline.

The water company claims the scheme is the cheapest and fastest way to boost water resources and combat the effects of future droughts.

However, documents released along with the proposals suggest there is a risk to river life and plants by changing the temperature, chemical make-up and salinity of the Thames.

Sarah Olney said: "I'm extremely concerned about these proposals, however, Thames Water have not notified me as to the true impact these plans will have on the river.

"These plans need to be available for proper scrutiny before they progress any further.

"The river is a part of all Londoners lives, and yet, every year we pump millions of litres of sewage into its waters.

"It's vital that we protect the Thames' fragile ecosystem and keep it clean for all Londoners. The scale of sewage dumping over the last few years clearly isn't doing this."

The Twickenham MP, Munira Wilson, has also challenged the proposals.

The main proposals affecting south west London involve:

* Thames Water will set up a new abstraction point between Teddington Weir and Hampton Court to take between 50 megalitres per day and 150 megalitres per day out of the river Thames. It is not clear what this would look like.

* This water will be transferred through a new pipeline to an existing tunnel that runs beneath London and then on to reservoirs in the Lee Valley to supply homes and businesses in the east of London and beyond.

* The water taken out of the river will be replaced by treated effluent which will pumped into the Thames further down the river towards Teddington Weir.

* This water will come from the Mogden Water Treatment Works in Isleworth, which is set to undergo a multi-million pound redevelopment and expansion.

* Getting the treated sewer water from Mogden to the Thames near the weir will involve building a new 15km pipeline.

Thames Water says these schemes, which could be completed by 2030, are the fastest and cheapest option to increase the amount of water needed to meet future demands.

Other proposals include efforts to cut down on leakage and the building of a new supersize reservoir south of Abingdon in Oxfordshire.

Thames Water justified the need for the schemes, saying: "Substantial water shortages face the whole of the South East of England. 

"The extreme heat and lack of water we experienced this summer is a clear indication of climate emergency first-hand. The predicted regional water demand is set to increase, with the number of people living and working in London and the Thames Valley forecast to grow significantly. 

"Every day, Thames Water currently supplies around 2.6 billion litres of water to customers across London and the Thames Valley. This is enough to fill 1,000 Olympic sized swimming pools. 

"The company forecasts that it will need an extra 1 billion litres of water every day for customers by 2075 to accommodate climate change and population growth."

The company's schemes involve spending up to £13 billion between 2025 and 2050, which will have to be recouped from customers through bills.

It argued they are necessary 'to build in future resilience for the benefit of customers, their children, grandchildren and the environment'.

However, small print in documents prepared by the company reveal the schemes carry a cost to the environment and river life.

No information has been provided on what the site to abstract water from the Thames and the second one to pump treated effluent back in to the river will look like. These are sensitive locations in conservation areas.

In terms of river life, company documents say the proposals have the 'potential to cause … minor to moderate water temperature change' along the river between Teddington Weir and Walton. There would also be a change in salinity – salt levels – along the river through to Battersea.

Significantly, they identify 'changes to freshwater and estuarine fish community structure and migration patterns', plus an alteration of the life-cycle of macroinvertebrates, which are insects in their nymph and larval stages, such as snails, worms, crayfish, and clams.

They also state the proposals could also harm numbers of angiosperms, which are flowering plants, and phytoplankton, which is a key part of the river ecosystem.

Residents will have the opportunity to ask for further details at the Richmond event on Monday. Details can be found here - https://thames-wrmp.co.uk/hearing-your-views/our-events/