More than 15,000 people signed petitions in response to the first public consultation on Thames Water's controversial "super sewer".
The £3.6bn Thames Tunnel project will see a 32km sewer built from west to east London. It will capture 39 million tonnes of untreated sewage overflowing into the Thames each year from the now inadequate Victorian sewer system. Work is scheduled to start in 2013 with completion due in 2020.
But campaigners across the capital are fighting plans to use a number of greenfield riverside parks as access sites, creating shafts for giant boring machinery, and in some cases permanent buildings.
More than 5,000 people signed a petition against such work in King Edward Memorial Park in Tower Hamlets, to the east of the capital.
Chairman of the Save Kemp group Carl Dunsire said the three-year programme of work would block almost the entire riverfront and cut off the river walkway.
"We don't have other open spaces to choose from and in an area that is already significantly deprived and has high density housing this park is vital," he added.
Dunsire said the proposed permanent structures would degrade the park and potentially excrete sewage fumes. The group had suggested brownfield alternatives to Thames Water, he added.
Meanwhile following pressure from the Save Kings Stairs Gardens (SKSG) group in Southwark, Thames Water bought brownfield site Chambers Wharf as a possible alternative. Current proposals would see works in the park for seven years.
"It would be lost to a whole generation of kids," said SKSG spokesman Roger Bilder. "It is natural habitat for a diverse range of wildlife with more than 500 mature trees and is widely used by tourists and the local community."
Bilder described the first consultation as "a sham", and said it used technical jargon that most people could not understand.
London Tideway Tunnel head Phil Stride said Thames Water was refining options and identifying alternatives. A final decision would be made after the second consultation in September, he confirmed.
Barn Elms Playing Fields, Richmond 5,013
King Stairs Gardens, Southwark 5,274
King Edward Memorial Park, Tower Hamlets 5,140