Environmental activists are fighting plans for massive tower blocks near Hackney Marshes, warning of flood risks and damage to local green spaces.
Waltham Forest Council has proposed 30-storey residential towers to house 9,000 people overlooking the marshes.
Campaign group Save Lea Marshes claims the development would scupper plans for East London Waterworks Park and threaten the area's ecology.
"Footfall on the marshes would massively increase," a spokesperson said.
The group warns building on the flood-prone New Spitalfields site in Leyton is "very, very risky".
"You can't just build multiple high rises on a floodplain next to a river in these times without putting future residents and current residents at serious risk," they said.
Hackney Wick residents faced flooding in January when the River Lea burst its banks.
Save Lea Marshes argues the proposals would "adversely impact the openness" of Hackney Marshes and increase flood risks.
The campaign page also highlights concerns about pets from new homes posing risks to "sensitive and easily disturbed species", a danger they claim is "not assessed" in the council's plan.
Waltham Forest says it will provide "ecological and biodiversity enhancements" to preserve the marshes' "verdant character".
While these plans fall under Waltham Forest Council's jurisdiction, some elements require approval from Hackney Council.
A Hackney Council spokesperson said no decisions have been made yet, adding: "As a consultee, we will carefully assess the plans and their impact on Hackney once they are submitted."
The Environment Agency will also be consulted on flood risks.
Objections to the plans must be submitted by October 9.
Hackney Marshes, one of London's largest areas of common land, covers 136 hectares along the western bank of the River Lea. The area has a rich history, having been drained since medieval times and later raised with rubble from World War II bomb damage.
