STOW – They may not menacingly jump out of water, devour fish or even feed on zooplankton.

But two invasive aquatic plants – the water chestnut and hydrilla – pose a threat to Chautauqua County’s ecology and economy as far as environmental and public officials here are concerned.

That is why the officials want boaters and other recreational users on and along the 42 miles of Chautauqua Lake’s shoreline to be on the alert this summer for the two species.

“This is the exact time when these plants are going to start popping up,” said Jeff Diers, Chautauqua County’s watershed coordinator.

Last summer, for the first time, the water chestnut plant was discovered in the lake by a consultant team performing unrelated work in the area. A “massive search party” of about 50 people was immediately assembled to traverse the lake, Diers said.

Seventeen water chestnuts in all, believed to have been deposited in the lake by geese, were found and removed. Each “nutlet” had the potential to spawn five plants. All were confined to the areas near Bemus Point and the mouth of the Chadakoin River near Jamestown, officials said.

Hydrilla plants, found in Tonawanda Creek last summer, have not yet been found in Chautauqua Lake, but officials are girding for their arrival. They fear the species could be introduced by those using their boats in both bodies of water.

“These are weeds that can cover the lake en masse,” said Linda Barber, president of the Chautauqua Watershed Conservancy. “You can’t use your boats. You can’t swim in the water. That’s why we want to be on top of this.”

Diers said an acre of the lake could have disappeared because of the water chestnut without last year’s intervention. The plant thrives in slow-moving water.

The invading plants would eventually explode over time.

“If left untouched year after year, that area of growth will keep extending toward the center of the lake,” said Diers.

“Once they start to take hold, they spread and quickly cause havoc on the ecosystem.”

County Executive Gregory J. Edwards added, “It basically eliminates all the oxygen for all the plant life and animal life in the system.”

Chautauqua County officials, mindful of the impact the species could have on the lake’s ecology, not to mention its vast recreation and tourism industry, have formulated the early battle plan to “get ahead” of any visits by the species this summer.

“With any invasive species, it’s always important to quickly identify a new introduction and remove it immediately,” Diers said.

Anyone who spots one of the plants is asked to call Diers at (716) 661-8915 or Edwards’ office at (716) 753-4211.

“We’ll get the experts out there and make an absolute determination of what the plant is and then professionally remove it,” Edwards said. “That’s the key. We have to stay ahead of this. We’re playing offense here. “That’s the only way we’re going to have a realistic chance,” he said.