At first glance, a hideous creature appeared to be reaching out of the dark depths to pull Julie Spelletich out of her kayak.

At first glance, a hideous creature appeared to be reaching out of the dark depths to pull Julie Spelletich out of her kayak.

The murky water around her was boiling, a warning that other loathsome monsters might be thrashing about just under the surface. But a closer look revealed that Spelletich was pulling the swamp thing — a mass of yellow floating heart — onto her watercraft on Little Squaw Lake in the Rogue River-Siskiyou National Forest.

The boiling water was simply bubbles being emitted by U.S. Forest Service divers Bruce Hansen and Mel Culp, who were busy at the bottom of the lake cutting off the stems of the yellow floating heart, a noxious aquatic weed that is highly invasive.

"The scuba divers have been cutting the plants down near the bottom," explained Barbara Mumblo, botanist with the Siskiyou Mountains Ranger District, of the project completed late last week. "It all floats to the surface, so we've been bringing it back to land to put it on a tarp to dry it out and remove it."

That's where Spelletich of Ashland comes in. She and Shelley Tanquary, of Medford, both members of the Native Plant Society, were volunteering to help remove the invasive plant that is threatening to choke off parts of the picturesque 12-acre lake.

Discovered in 2008 in the remote lake about eight miles east of Applegate Dam in the Applegate River drainage, yellow floating heart, whose Latin alias is Nymphoides peltata, is on the Oregon Department of Agriculture's noxious weed list.

Originally from Asia and sold at aquatic plant stores in Oregon before it was banned, yellow floating heart also has been found in a shallow lake in the Umpqua National Forest, as well as in ponds and lakes in the Willamette Valley and near Portland.

"Up north, they've been spraying it with herbicides," Mumblo said. "But here we wanted to give it our best try with the manual method first. This lake gets a lot of recreational use."

The divers are using an erosion blanket commonly used in gardening and landscaping to cover what remains of the plant at the bottom of the lake. After wrestling with the material in a slow underwater dance, they laid rebar on it to keep it in place.

The idea is to stop the life-giving sunlight from filtering down through the water. Similar methods have been successful in other areas to snuff out the plant, Mumblo said. A test strip employing the erosion blanket was used last year, she said, and no plants grew up through the material, although some did emerge up around the side of it. "Last year, we spent the summer just getting the flowers and capsules off," Mumblo said. "We did not want it to seed. The seeds float and have these little furry edges that may get caught in the wings of ducks and geese."

In fact, experts believe waterfowl may be helping spread the plant when they fly to a pond or lake.

"We want people to know we have this invasive weed," said Leah Lentz, the forest's noxious weed coordinator, who was also working on the project. "When you get to a site where there are only a few plants, it is easy to eradicate. We've been out here for three years and we are still trying to eradicate it.

"But every year we come out here we've learned something new," she added. "We are hoping by covering it we will finally get rid of it."

They have built a boom about 140 feet long which is some 40 feet from shore at the widest point.

"I'm not sure how far the plant would grow out into the lake — this lake is 50 feet deep in the center," she said. "We've found it out to about 20 feet deep.

"It is rooted at the bottom and floats on the top of the water," she added. "There will be a few nodes along the plant. There are roots at every one of those nodes. So if it breaks off, that piece with the node can take root again. It's quite amazing."

She wasn't being complimentary.

Out in the lake, Hansen and Culp came up for a break. "It gets pretty silty — we can only see a little bit," observed Culp, whose main job is working as a forestry technician in the Wild Rivers Ranger District. She also is a veteran scuba diver and instructor.

"Two of us down there would just stir up the muck that much more," added Hansen, an ecologist for the U.S. Forest Service Pacific Northwest Research Station in Corvallis, who also serves as the agency's regional scuba and snorkel safety officer. "What I am doing is following her bubbles, then holding the rebar there for her so it is ready when she is ready to grab it."

She was wearing a wet suit; he was in a dry suit. "In about 45 minutes she might start feeling cold, but I'll be able to go for about another half-hour after that," he said.

A 1978 graduate of Illinois Valley High School in Cave Junction, Culp saw a smallmouth bass that was about 20 inches long while working on the project. "It lives underneath that log," she said of a nearby fallen tree trunk. "I've seen it twice. There are also some smaller guys. They were curious. They were swimming all around me."

Meanwhile, they won't know until next summer whether their attempts to eradicate the plant from the lake was successful. "It stays submerged all winter long under the surface," Mumblo said. "We will come back in July to see if it comes back."

Reach reporter Paul Fattig at 541-776-4496 or email him at pfattig@mailtribune.com.