There are plenty of rumors swirling about what’s floating in Tahoe’s 1,645-feet-deep water. But Colin West can tell you what’s actually down there.

West is the founder and executive director of Clean Up the Lake, a nonprofit that organizes scuba divers to pick up the garbage and trash that’s stuck at the bottom of Lake Tahoe. He can talk for a long time about the trove of trash he’s found — and picked up — in the lake. West said he’s found everything from the quotidian — plastic bottles, sunglasses, beer cans, towels, a couple of iPhones — to the more unusual: anchors, pieces of sunken boats that have likely broken up after sinking, even underwear. West has discovered those intimates just offshore of the nude beach.

Trash has become a lightning rod issue this summer in Tahoe, as waves of new visitors have left copious amounts of garbage and litter in their wake. But West said that trash is nothing new in Tahoe. He’s found decades-old evidence to prove it.

“We have a perfectly preserved 44-year-old bicentennial Diet Pepsi pull-tab can,” he said. “So this problem is easily 44-plus years old.”

On a perfect Tahoe day in late August — one of the only blue-sky days sandwiched between weeks of storms, lightning, wildfires and smoke — I boarded a motor boat early in the morning at the Zephyr Cove marina on Tahoe’s southeast shore. We sped along the shoreline to meet up with West’s crew.

Three boats, plus a couple of jet skis and inflatable zodiac rafts, were moored about a hundred yards off Nevada Beach. Twenty people were on board, most with neoprene wetsuits pulled up, getting ready for a day of scuba diving. It was the first of six days when Clean Up the Lake organized dives along the East Shore to collect and document sunken trash. The nonprofit received funding from the Lake Tahoe license plate grant issued by the Nevada Division of State Lands, as well as a grant from the Nevada Department of Environmental Protection and the United States Environmental Protection Agency.

Scientists found microplastics in Lake Tahoe in 2018, and research shows that these uber-small fragments of plastic wind up in the food chain, the environment, and drinking water. Clean Up the Lake is one of the only groups that’s organizing trash pick-ups below Tahoe’s surface.

Scuba divers pick up trash in Lake Tahoe near Nevada Beach on Thursday, August 27, 2020. Photo: Clean Up The Lake 501(c)3, Jason Smith

Photo: Clean Up The Lake 501(c)3, Jason Smith

Scuba divers pick up trash in Lake Tahoe near Nevada Beach on Thursday, August 27, 2020.

“It’s really disheartening to know that enough plastic has been in the lake long enough to be broken down into microplastics,” said Amelia Gotham, events and fundraising coordinator for Clean Up the Lake. “It’s fighting an uphill battle at the moment. But there are a lot of people that care, a lot of people taking action right now.”

West stood at the back of one of the boats to give a dive briefing to his team and explain how the clean-up would work underwater. The plan was to station one group of divers at the south end of the beach, and another a mile north. They used the app Strava to measure the distance. The two groups of four divers — each buddied up — would then swim toward each other.

Each diver had three tanks of air for the three dives they would conduct throughout the day. West planned for enough time underwater so they could do a thorough job. For the most part, the divers would stick to depths between 15 and 25 feet, a zone West said is the “sweet spot” for trash collection.

Small items would get stashed in a mesh bag that each diver swam with. Bigger items required a coordinated effort with the jet skis, zodiac rafts, and free divers swimming above the scuba divers.

West developed specific hand signals and a method for larger things that included a pulley system. “Which, at the moment, is a rock with duct tape around a rope,” West tells his team.

When a scuba diver encountered a larger item too big to put in their mesh bag — I saw them haul out big cables, a panel that must have come from a boat, even tires — then they signaled a free diver swimming above them. The free diver dropped the weighted rope and communicated with the people on the jet ski and the raft, who would pull the trash up. The raft was equipped with trash bags to store the day’s findings.

Scuba divers pick up trash in Lake Tahoe near Nevada Beach on Thursday, August 27, 2020. Photo: Clean Up The Lake 501(c)3, Jason Smith

Photo: Clean Up The Lake 501(c)3, Jason Smith

Scuba divers pick up trash in Lake Tahoe near Nevada Beach on Thursday, August 27, 2020.

Some things the divers have to leave inside the lake. If it’s too heavy, or there’s too much, the divers will mark the item with GPS so they can come back to it with larger equipment. Historical items older than 50 years stay put and are reported to the state.

This system works. Earlier in the summer, West dove along the north shore of Donner Lake and collected 3,700 pounds of trash.

“Alright guys, let’s get in the water,” West said.

With their BCs inflated, the divers slipped into the lake and floated on the surface. When everyone was in the water, they deflated their vest and submerged. The surface of the lake was glittering with morning sun.

West started Clean Up the Lake two years ago. He’s a former sommelier and he also runs a film company called Wineram that creates movies and shows for the wine industry. He travels quite a bit. On a trip to Belize, he saw how plastic had overwhelmed the beaches. When he returned home to Tahoe, he realized the problem was here, too.

“The reason why you can look under the surface [of the lake] is because it’s still at a point that we can really save it,” he said.

In 2021, West hopes to pick up even more trash in Lake Tahoe. He’s organizing an unprecedented campaign to scuba dive along the circumference of the lake and pick up trash. Teams will swim 72 miles total. West had originally planned the circumference dive for this summer, but the pandemic pushed back his plans. So for now, he’s focusing on this series of test dives along the East Shore.

About 10 minutes into their dive, the jet ski shouted something to the zodiac raft. They were about 50-feet away from the boat I was stationed in. I heard the words “concrete” and “bucket.” The divers had found remnants of old buoy anchors, stubborn pieces of history just offshore of Nevada Beach. Too heavy to pick up today, the divers marked the buckets full of concrete on GPS so they could coordinate a pick-up at a later date.

Scuba divers pick up trash in Lake Tahoe near Nevada Beach on Thursday, August 27, 2020. Photo: Clean Up The Lake 501(c)3, Jason Smith

Photo: Clean Up The Lake 501(c)3, Jason Smith

Scuba divers pick up trash in Lake Tahoe near Nevada Beach on Thursday, August 27, 2020.

On the other side of the beach, the second team of divers was already swimming in the water.

They too found some surprising items. Two tires pulled up from the lake were attached to the back of the jet ski. One was falling apart and deteriorating. I couldn’t help but wonder who would toss a set of tires into the lake.

In six days diving, Clean Up the Lake covered water off-shore of Nevada Beach, Zephyr Cove, Sand Harbor and Crystal Bay.

In Sand Harbor — a state park famous for its postcard-perfect, aqua marine-colored water and granite boulders — West and his team filled 12 contractor-sized garbage bags with mostly aluminum cans.

West inventories and weighs all the trash his crew picks up before the items go into the dumpster. After his dives, he texted me pictures of his finds organized neatly on tarps. Some things were recognizable — a dirty towel, cables, a lot of golf balls. There was a crinkled bag of chips, with the Doritos logo still legible. Ropes and cinder blocks. A bohemian-style women’s hat. One day, West pulled up a Sony CFS210 boom box that plays cassette tapes. He has also found entire engine blocks in the lake.

He weighed all the trash: 2,248 pounds collected in just six miles.

“I’ve always said you need to look under the surface to see the problem,” he said.

Editor’s note: In an earlier version of this story, West said that the bicentennial Pepsi tab found in the lake indicated that the issue of trash was at 46 years old. The Bicentennial took place 44 years ago, in 1976. This story has been updated to reflect that change.

Julie Brown is a contributing editor for SFGATE covering Lake Tahoe. Email: julie.brown@sfgate.com | Twitter: @imjuliebrown

We’re launching our very own newsletter all about Lake Tahoe. For weekly updates, interviews and profiles from a Tahoe insider, sign up here.