FORT LAUDERDALE, Fla. – Nearly 70 feet below the ocean's surface, off the coast of Fort Lauderdale, is a reminder of a bad idea from the 1970s: hundreds of thousands of used tires sitting on the ocean floor.

They were supposed to form an artificial reef and attract fish. Instead, they left behind a wasteland that crews have tried to clean up for years.

The Industrial Divers Corporation of Fort Lauderdale was contracted by the state in 2015 to remove the tires, and has continued to work over the last four years. In that time, divers have removed nearly 250,000 tires.

"This is the first, that I know of, first full-time multiyear effort that to clean up the reef," said diving coordinator Alex Delgado.

Removing the old tires is a two-part process: Dive crews bundle and rig the tires underwater, then slowly hoist them up and onto their barge. Much of the work depends on current, weather, and marine conditions.

On a good week, Delgado said the crew can recover anywhere from 2,000 to 5,000 tires.

When bundles of tires were first dumped about a mile offshore in the early 1970s, the purpose was twofold: to have a place to dispose of used tires, and to create a reef to attract marine life.

"But then when the clips rusted through and the straps came loose, all the tires just kind of fell apart," said Dr. Pat Quinn, Broward County's marine biologist and project manager.

Some loose tires damaged coral, and it's estimated only 10% of the tires ever became marine habitat, according to Quinn.

Florida officials enlisted the help of the military in 2007.

"They removed about 72,000 tires. But then they got to the point where they had so many operations around the world they couldn't come back," Quinn said.

According to a report from Florida's Department of Environmental Protection, state lawmakers authorized $1.8 million for the project in 2016.

Another company, B & J Martin, Inc., was awarded money for a pilot project in 2017, but the contract expired in October after the contractor was unable to obtain the necessary state and federal level permits.

The Legislature in 2017, 2018 and 2019 appropriated an additional $4.5 million for reef protection which is currently being used to remove tires from the reef under the Industrial Divers contract and for other reef protection efforts.

The project currently underway might have an initial negative environmental impact. But Quinn said the project will benefit the health of the reef in the long run.

"The tire field out there is a cancer in the reef, and so this cancer needs to be removed. If you have a tumor, you're going to go to the doctor. The doctor is going to cut you open, do damage to healthy tissue, to remove that bad tissue," Quinn said.

An estimated two-thirds of the tires remain.

IDC Quality Assurance Coordinator Rocco Galletta said the company welcomes the challenge.

"It's just something we can do for sure. It's not necessarily hard. It takes a lot of persistence to stay with it," Galletta said.