The campaign against the raising of the Warragamba Dam wall has stepped up a notch, with more than 20 events planned in coming months.

The Colong Foundation for Wilderness held a training day on Saturday at Faulconbridge, where 50 volunteers from the Blue Mountains and western Sydney brushed up their campaign skills.

“At the event we planned over 20 campaign actions including protests, market stalls, letter boxing and information sessions to make sure politicians listen to our message about this destructive dam proposal,” said Colong Foundation’s Give a Dam campaigner Harry Burkitt.

“There is no better way to counter the misinformation being spread by the NSW government than having passionate people on the ground talking to the community.”

Almost 21,000 people have signed an online Give a Dam petition urging the government to drop the plan and not inundate World Heritage listed national park.

Meanwhile, the state government has provided a leaflet to 70,000 Sydney households, including in last week’s Hawkesbury Gazette, updating the community on Warragamba Dam developments.

It focuses on how the plan will reduce the flood risk in the Hawkesbury-Nepean Valley, but includes little information about the environmental or Aboriginal heritage impacts.

“Spending tens of thousands on community updates and false advertising is a disgraceful act by the government, when it will have a disastrous impact on environmental values and Indigenous culture,” Mr Burkitt said.

He said 500 submissions were being sent to the government in response to the community update.

It’s proposed to raise the Warragamba Dam wall by 14 metres to reduce flood risk in the Hawkesbury-Nepean Valley. The plan was announced in June 2016 by then premier Mike Baird.

The government is preparing an Environmental Impact Statement for public exhibition, expected later this year.