The "reef balls" were made at Dominion Diving in Dartmouth.
Each weighs about 1,000 kilograms.
J.D. Irving Ltd. is funding the project as a way to offset the fact they are filling in part of Halifax Harbour in an expansion of its shipyard.
"We agreed to do this. Now I will tell you Irving Shipbuilding is investing a significant amount of our own money and the owners' money in the facility," said Kevin McCoy, president of Irving Shipbuilding.
He said the cost of creating and dropping the reef balls into the harbour is $200,000.
Chris Morrisey, executive director for Clean Nova Scotia, said he expects other sponsors to fund other reef balls projects in Halifax Harbour next spring.
“We’d like to see thousands of these in the water, if possible -- and we won’t stop just at the Halifax Harbour, this is a program we envision going much broader throughout the province of Nova Scotia and throughout Atlantic Canada,” he said.