The once very polluted waters off Sabin Point Park in Riverside have become clean enough that the Rhode Island Department of Environmental Management and The Nature Conservancy decided to construct an artificial reef.

“We didn’t know what we were going to find, but one year into it and we’re pleasantly surprised,” The Nature Conservancy’s John Torgan said.

The project began last year when 64 cement blocks were lowered into the waters by a crane on a barge.

Torgan described the cement blocks as looking like half whiffle balls. Each reef ball is 4 feet across with 17-24 holes in each. The blocks each weigh approximately 1,300 pounds.