Larry Gilpin Sr. doesn't mind the dense mats of aquatic weeds that erupt along Thurmond Lake's coves and sandy points in late summer.
"It's definitely made a difference in the fishing," the veteran angler said. "It keeps big fish out of the sun and makes cover for baitfish."
But the Army Corps of Engineers, which manages the 70,000-acre lake, isn't as enamored with the unwanted hydrilla -- a fast-growing African transplant rapidly spreading throughout the lake.
"There's no way to completely get rid of it," said Corps Chief Ranger Allen Dean, who has waged an ongoing battle since the hydrilla was first discovered near Cherokee boat ramp in 1995.
"You can spray it with herbicide, and it just comes right back," he said. "We started out trying to treat every patch we found. Now we're just trying to treat around parks and boat ramps."
The lush green weed can grow as tall as 18 feet beneath the water. Although it provides cover and attracts gamefish like largemouth bass, it can easily take over a reservoir and cause problems, Chief Ranger Dean said.
It's also expensive to control. By the time contractors finish $22,000 in herbicide applications this weekend, the Corps will have spent more than $230,000 fighting the unwanted weed.
The hydrilla, by the way, is still winning.
The first patch -- discovered in fall 1995 -- covered only 55 acres. "This year, even with the spraying, we estimate about 1,000 acres," Chief Ranger Dean said. "It'll be even more next year."
The hydrilla likely found its way into Thurmond Lake aboard a boat propeller that had been in lakes where hydrilla was already present.
Lake Murray near Columbia has fought infestation problems for 15 years. The weed is also a problem in South Carolina's Lake Wateree and Lake Keowee.
So far, the hydrilla has not been found in Lake Russell and Lake Hartwell, two other reservoirs upstream from Thurmond Lake, Chief Ranger Dean said.
Although hydrilla has completely taken over shallow reservoirs in Florida, Georgia and other states, Thurmond Lake's steep shorelines make it unlikely the hydrilla will ever control the reservoir.
"Because this lake is deep, it can only grow near shore," he said. "But it can be 18 feet deep under the water."
This year, herbicide treatment programs are under way in heavily used areas of Thurmond Lake, mainly Little River, Cherokee, Lake Springs, Clarks Hill Park and Tradewinds Marina.
"With the lake being lower because of dry weather, it's more visible, and we've gotten about a dozen calls about it -- just this week," he said.
For anglers, the hydrilla continues to offer prime fishing habitat. But even diehard fishermen like Mr. Gilpin don't want the weed to take over.
"If the corps can semicontrol it, and not let it get totally out of hand, it will greatly improve the fishing," he said.