The call to help save Minnamurra River from a plan to increase sand mining was heard by hundreds on Sunday.
They turned out with placards and banners urging Boral to put aside its scheme to expand its Dunmore Lakes mine.
Both Kiama and Shellharbour councils have opposed the proposal, but Boral has taken it to the NSW Planning Department for approval.
The group - Friends of Minnamurra River - organised the weekend protest action, concerned if the plans go ahead threatened species and the health of the river would be jeopardised.
Photo source. Steve Gillespie