Around 100 people came together and a pipe ceremony and feast was held to bless the initiative.
Twenty-four people have now joined a group that plans to drag the Red River starting this week.
Sheenah Fontaine was at Sunday's ceremony. Her sister-in-law, Amber Guiboche, went missing in 2010.
“It's really hard thinking of where she is, how she is, if she's alive,” said Fontaine. “It really hurts the heart. It affects your brain, your thoughts.”
Sheenah said she supports the search.
“It's a step closer to answers," said Fontaine. "You never know what you could find in this Red River, if it's not Amber we find, it could be somebody else.”
The group wants to head out on boats and comb the river bed with chains and hooks to find other bodies or clues that might shed light on cases involving missing people.
The push to search the river came from Bernadette Smith after Fontaine’s body was found.
Smith has been searching for her sister, Claudette Osborne. since she went missing in 2008.
Some of those present Sunday said they have missing women in their lives and hoped the effort will bring closure.