Rowers fear they are being squeezed off Sydney's waterways, which they say have become highways for ferries and awash with accident blackspots.

The state's peak body for the sport, Rowing NSW, says the concerns of rowers are being ignored as increasing congestion along the Parramatta River threatens to capsize their sport.

The organisation will launch a campaign on Saturday to lobby the state government to give them a greater voice in waterway decisions, with the key aim of stopping the construction of a new ferry wharf and interchange on the river at Rhodes.

The state government is finalising the design of the wharf, which will provide a public transport route to and from the city for a booming residential population on the ​peninsula.