Fighting the aquatic invasion at Mosquito Creek Lake will require careful planning

Pittsburgh District USACE
Published Oct. 20, 2021
water weeds

Col. Adam Czekanski, commander of the U.S. Army Corps of Engineers Pittsburgh District, listens to staff explain the threats caused by Hydrilla and other invasive aquatic plants at Mosquito Creek Lake in Cortland, Ohio, Sept. 28, 2021. The Mosquito staff is working with the Ohio Department of Natural Resources, the Ohio Environmental Protection Agency and Cleveland Metroparks to determine a solution to remove or treat invasive vegetation growing in the lake while maintaining the vegetation beneficial to the lake’s ecosystem and fishery. (U.S. Army Corps of Engineers Pittsburgh District photo by Michel Sauret)

water weeds

Col. Adam Czekanski, commander of the U.S. Army Corps of Engineers Pittsburgh District, listens to staff explain the threats caused by Hydrilla and other invasive aquatic plants at Mosquito Creek Lake in Cortland, Ohio, Sept. 28, 2021. The Mosquito staff is working with the Ohio Department of Natural Resources, the Ohio Environmental Protection Agency and Cleveland Metroparks to determine a solution to remove or treat the vegetation growing in the lake while maintaining the vegetation beneficial to the lake’s ecosystem and fishery. (U.S. Army Corps of Engineers Pittsburgh District photo by Michel Sauret)

water weeds

Jamison Conley, a park ranger and resource manager for the U.S. Army Corps of Engineers Pittsburgh District, holds a strand of Hydrilla, an invasive aquatic plant at Mosquito Creek Lake, in Cortland, Ohio, Sept. 28, 2021. The Mosquito staff is working with the Ohio Department of Natural Resources, the Ohio Environmental Protection Agency and Cleveland Metroparks to determine a solution to remove or treat invasive vegetation growing in the lake while maintaining the vegetation beneficial to the lake’s ecosystem and fishery. (U.S. Army Corps of Engineers Pittsburgh District photo by Michel Sauret)

water weeds

Jamison Conley, a park ranger and resource manager for the U.S. Army Corps of Engineers Pittsburgh District, uses a rake to scoop out Hydrilla, an invasive aquatic plant at Mosquito Creek Lake, in Cortland, Ohio, Sept. 28, 2021. The Mosquito staff is working with the Ohio Department of Natural Resources, the Ohio Environmental Protection Agency and Cleveland Metroparks to determine a solution to remove or treat invasive vegetation growing in the lake while maintaining the vegetation beneficial to the lake’s ecosystem and fishery. (U.S. Army Corps of Engineers Pittsburgh District photo by Michel Sauret)

water weeds

Col. Adam Czekanski, commander of the U.S. Army Corps of Engineers Pittsburgh District, looks out to a stretch of water lotus that is native to the region but overgrowing at Mosquito Creek Lake, in Cortland, Ohio, Sept. 28, 2021. The Mosquito staff is working with the Ohio Department of Natural Resources, the Ohio Environmental Protection Agency and Cleveland Metroparks to determine a solution to remove or treat invasive vegetation growing in the lake while maintaining the vegetation beneficial to the lake’s ecosystem and fishery. (U.S. Army Corps of Engineers Pittsburgh District photo by Michel Sauret)

water weeds

Water lotus is native to the region but overgrowing at Mosquito Creek Lake, in Cortland, Ohio, Sept. 28, 2021. The Mosquito staff is working with the Ohio Department of Natural Resources, the Ohio Environmental Protection Agency and Cleveland Metroparks to determine a solution to remove or treat invasive vegetation growing in the lake while maintaining the vegetation beneficial to the lake’s ecosystem and fishery. (U.S. Army Corps of Engineers Pittsburgh District photo by Michel Sauret)

water weeds

Jamison Conley, a park ranger and resource manager for the U.S. Army Corps of Engineers Pittsburgh District, holds a strand of Eurasian watermilfoil, an invasive aquatic plant at Mosquito Creek Lake, in Cortland, Ohio, Sept. 28, 2021. The Mosquito staff is working with the Ohio Department of Natural Resources, the Ohio Environmental Protection Agency and Cleveland Metroparks to determine a solution to remove or treat invasive vegetation growing in the lake while maintaining the vegetation beneficial to the lake’s ecosystem and fishery. (U.S. Army Corps of Engineers Pittsburgh District photo by Michel Sauret)

water weeds

Jamison Conley, a park ranger and resource manager for the U.S. Army Corps of Engineers Pittsburgh District, holds a strand of Eurasian Watermilfoil, an invasive aquatic plant at Mosquito Creek Lake, in Cortland, Ohio, Sept. 28, 2021. The Mosquito staff is working with the Ohio Department of Natural Resources, the Ohio Environmental Protection Agency and Cleveland Metroparks to determine a solution to remove or treat invasive vegetation growing in the lake while maintaining the vegetation beneficial to the lake’s ecosystem and fishery. (U.S. Army Corps of Engineers Pittsburgh District photo by Michel Sauret)

CORTLAND, Ohio – Mosquito Creek Lake is facing an aquatic invasion that is green, thick, and sometimes slimy. The invaders are responsible for damaging boat motors and slowly choking out fish and plant life by depriving them of oxygen.

Thankfully, the U.S. Army Corps of Engineers Pittsburgh District is planning to fight back.

water weeds
Mosquito Creek
Col. Adam Czekanski, commander of the U.S. Army Corps of Engineers Pittsburgh District, listens to staff explain the threats caused by Hydrilla and other invasive aquatic plants at Mosquito Creek Lake in Cortland, Ohio, Sept. 28, 2021. The Mosquito staff is working with the Ohio Department of Natural Resources, the Ohio Environmental Protection Agency and Cleveland Metroparks to determine a solution to remove or treat the vegetation growing in the lake while maintaining the vegetation beneficial to the lake’s ecosystem and fishery. (U.S. Army Corps of Engineers Pittsburgh District photo by Michel Sauret)
Photo By: Michel Sauret
VIRIN: 210928-A-TI382-0545


No, the lake is not facing lagoon monsters inhabiting the waters. Instead, the lake faces an infestation of water weeds growing out of control.

“The U.S. Army Corps of Engineers’ mission at Mosquito Creek Lake is to ensure your lake is safe and we improve the fishery threatened by these invasive plants,” said Timothy Hough, the resource manager at the lake, which is managed by the Pittsburgh District. “We are committed to preserving the lake’s natural resources and wildlife, both above and below the surface of the water.”

The lake has been known to have an aquatic plant problem for years. Although that does not sound as threatening as monstrous creature lurking in the waters, these weeds pose real threats to the lake’s ecosystem including its fishery.

The latest aquatic threat to the lake is called Hydrilla, named after Hydra, the 9-headed serpent of Greek mythology because it can grow an entire new plant from a tiny stem fragment.

water weeds
Mosquito Creek
Jamison Conley, a park ranger and resource manager for the U.S. Army Corps of Engineers Pittsburgh District, holds a strand of Hydrilla, an invasive aquatic plant at Mosquito Creek Lake, in Cortland, Ohio, Sept. 28, 2021. The Mosquito staff is working with the Ohio Department of Natural Resources, the Ohio Environmental Protection Agency and Cleveland Metroparks to determine a solution to remove or treat invasive vegetation growing in the lake while maintaining the vegetation beneficial to the lake’s ecosystem and fishery. (U.S. Army Corps of Engineers Pittsburgh District photo by Michel Sauret)
Photo By: Michel Sauret
VIRIN: 210928-A-TI382-0585


This invasive species prevents oxygen production in the water by blocking sunlight and chocking out native species, including other plants that help the lake’s ecosystem. Hydrilla blankets and traps fish, which impedes spawning. It is fast-growing and causes an increase in water temperatures and pH levels.

“Hydrilla is very concerning, invasive, and more destructive than any other plant in the lake,” said Jamison Conley, a park ranger at the lake.

Yet Hydrilla is not the only weed causing harm to the lake. Eurasian watermilfoil, also invasive, grows in heavy mats that entangle other wildlife. The American Lotus is native to Mosquito, but as it overgrows, it expels oxygen from the water and can produce toxins harmful to other plants. The lake also faces a growing nuisance of duckweed, watermeal, pondweed and coontail.

water weeds
Mosquito Creek
Jamison Conley, a park ranger and resource manager for the U.S. Army Corps of Engineers Pittsburgh District, holds a strand of Eurasian Watermilfoil, an invasive aquatic plant at Mosquito Creek Lake, in Cortland, Ohio, Sept. 28, 2021. The Mosquito staff is working with the Ohio Department of Natural Resources, the Ohio Environmental Protection Agency and Cleveland Metroparks to determine a solution to remove or treat invasive vegetation growing in the lake while maintaining the vegetation beneficial to the lake’s ecosystem and fishery. (U.S. Army Corps of Engineers Pittsburgh District photo by Michel Sauret)
Photo By: Michel Sauret
VIRIN: 210928-A-TI382-0667


“Many of these species start out providing great cover and structure for fish, but after time, they progressively start to reduce the diversity, oxygen, and ability to spawn,” Conley said.

According to Conley, in addition to harming aquatic life, these water vegetations can tangle around boat motors, irritating local fishermen and recreational boaters.

“We are already seeing entangled props, clogged motors, and the inability to fish from the shore or access areas with a boat,” he said.

Conley said they plan on removing only the weeds harming the lake, while keeping vegetation in the water that benefit fish population. Mosquito is especially vulnerable to harmful plants because of its shallow waters. Depths in the lake range between eight and 15 feet in most areas. Deeper lakes do not have the same problem because aquatic vegetations rooted in the soil cannot reach the water surface.

water weeds
Mosquito Creek
Col. Adam Czekanski, commander of the U.S. Army Corps of Engineers Pittsburgh District, looks out to a stretch of water lotus that is native to the region but overgrowing at Mosquito Creek Lake, in Cortland, Ohio, Sept. 28, 2021. The Mosquito staff is working with the Ohio Department of Natural Resources, the Ohio Environmental Protection Agency and Cleveland Metroparks to determine a solution to remove or treat invasive vegetation growing in the lake while maintaining the vegetation beneficial to the lake’s ecosystem and fishery. (U.S. Army Corps of Engineers Pittsburgh District photo by Michel Sauret)
Photo By: Michel Sauret
VIRIN: 210928-A-TI382-0767


“There are several methods that are commonly used to manage these species. Unfortunately, each one of these methods comes with some risks,” said Conley.

Those methods include harvesting, chemical treatment and dredging. Mosquito Creek Lake staff is investigating each option with the help of the Ohio Department of Natural Resources, the Ohio Environmental Protection Agency and Cleveland Metroparks.

Herbicides are effective at vegetation control, but since the city of Warren, Ohio, receives drinking water from the reservoir, options are limited. The Ohio EPA is narrowing it down to a few treatments to target specific vegetation without harming the rest.

Using an aquatic weed harvester is quick and effective on the water, but it also risks making the Hydrilla and Lotus problems worse.

“Hydrilla spreads by fragmentation, which means if you cut it, it will spread. Lotus has rhizomes that grow out when cut, which cause it to spread, also,” Conley said.

water weeds
Mosquito Creek
Jamison Conley, a park ranger and resource manager for the U.S. Army Corps of Engineers Pittsburgh District, uses a rake to scoop out Hydrilla, an invasive aquatic plant at Mosquito Creek Lake, in Cortland, Ohio, Sept. 28, 2021. The Mosquito staff is working with the Ohio Department of Natural Resources, the Ohio Environmental Protection Agency and Cleveland Metroparks to determine a solution to remove or treat invasive vegetation growing in the lake while maintaining the vegetation beneficial to the lake’s ecosystem and fishery. (U.S. Army Corps of Engineers Pittsburgh District photo by Michel Sauret)
Photo By: Michel Sauret
VIRIN: 210928-A-TI382-0532


Finally, dredging can make the water deeper to prevent certain species from growing, but it is expensive and can cause instant damage to aquatic wildlife and release pollutants in the sediment. It can also release fragments and seeds that start new plants.

“We will find the appropriate treatment for each area of the lake. Chances are each location requires a different solution,” Conley said.

Corps staff will work diligently with their Ohio environmental partners to address the problem without disrupting the lake’s ecosystem, he said.

The upcoming fall and winter months will help contain the growth of water vegetation. Then lake staff will decide on a plan by spring, and they will work with their partners to eradicate the problem by summer, when aquatic vegetation growth is the most aggressive. They will decide on solutions that remove harmful plants without damaging good vegetation beneficial to Mosquito’s fishery, Conley said.

water weeds
Mosquito Creek
Jamison Conley, a park ranger and resource manager for the U.S. Army Corps of Engineers Pittsburgh District, holds a strand of Eurasian watermilfoil, an invasive aquatic plant at Mosquito Creek Lake, in Cortland, Ohio, Sept. 28, 2021. The Mosquito staff is working with the Ohio Department of Natural Resources, the Ohio Environmental Protection Agency and Cleveland Metroparks to determine a solution to remove or treat invasive vegetation growing in the lake while maintaining the vegetation beneficial to the lake’s ecosystem and fishery. (U.S. Army Corps of Engineers Pittsburgh District photo by Michel Sauret)
Photo By: Michel Sauret
VIRIN: 210928-A-TI382-0689


In addition to working with state partners, the Mosquito Lake staff needs the public’s help.

“We ask the public to help us from spreading Hydrilla and other weeds to other water sources. This can be done by removing any water or mud off of you, your boat, pets, or other items that make contact with the water, before leaving,” Conley said.

He recommends people clean, drain and dry their vessels before transporting them from one body of water to another. Boat operators should clean live wells, ropes, trailers, and anchors thoroughly.

“We want you to know we value your lake as much as you do. With your help, we will continue to have a safe and healthy Mosquito Creek Lake for years to come,” Conley said.

Mosquito Creek Lake is one of 16 flood-control reservoirs operated by the Pittsburgh District. The project provides flood protection for the Mahoning River Valley as well as the Beaver and upper Ohio rivers.

water weeds
Mosquito Creek
Water lotus is native to the region but overgrowing at Mosquito Creek Lake, in Cortland, Ohio, Sept. 28, 2021. The Mosquito staff is working with the Ohio Department of Natural Resources, the Ohio Environmental Protection Agency and Cleveland Metroparks to determine a solution to remove or treat invasive vegetation growing in the lake while maintaining the vegetation beneficial to the lake’s ecosystem and fishery. (U.S. Army Corps of Engineers Pittsburgh District photo by Michel Sauret)
Photo By: Michel Sauret
VIRIN: 210928-A-TI382-0750