Tag Archives: lake norman

750 Grass Carp Released in Lake Norman

Charlotte Water, in partnership with NC Department of Environmental Quality, Lake Norman Marine Commission, and Duke Energy released another 750 Grass Carp into Lake Norman. The Grass Carp are part of a broader aquatic weed management program to address the ongoing Hydrilla infestation in the lake. More information regarding the Hydrilla infestation and it’s affect on drinking water intakes can be found here.

Approximately 22,000 Grass Carp have been released into Lake Norman since 2018. The fish have been very effective in managing the Hydrilla infestation such that recreational activities in the lake are fully restored.

To learn first hand what a fish release is like, read our 2019 article about the release of 4,000 Grass Carp at Ramsey Creek Park.

More information about the Lake Norman Hydrilla Management Project.

Stocking Lake Norman with Sterile Grass Carp to Combat the Invasion of Non-Native Hydrilla

On April 16th, approximately 4,000 sterile grass carp were released from Ramsey Creek Park to control the growth of hydrilla on Lake Norman. The total number of the grass carp will be about 12,330. A recent comprehensive survey performed by NC State found active hydrilla growth in 640 acres on Lake Norman. The addition of 12,330 grass carp along with the previous 10,200 that were stocked May 2018 will help largely eliminate active hydrilla growth in the next 2-3 years.

Charlotte Water owns and operates two drinking water intakes as the water supply for our community; one at Lake Norman and another at Mountain Island Lake. Aquatic weeds can pose a nuisance to water suppliers at their drinking water intakes by clogging pumps or as a biological contaminant that must be treated. There are a variety of ways to manage aquatic weeds. Complete eradication is often impossible but suppression is achievable.

DCIM100MEDIADJI_0126.JPG
Mr. Fish truck that transported grass carp to Ramsey Creek Park

The Lake Norman Marine Commission releases these fish because hydrilla is an aggressive invasive non-native aquatic weed that the grass carp like to eat. Left unchecked, hydrilla can devastate the balance of the lake’s ecosystem. It forms nearly impenetrable mats of stems and leaves at the surface of the water, crowding out other vegetation with its rapid growth. Hydrilla was originally introduced in the U.S. as an aquarium plant decades ago and can now be found in many water reservoirs nationally due to accidental releases.

The problem with many invasive species is that they have no natural predators in the regions where they are accidentally introduced. This leads to explosive population growth which puts a heavy strain on the resources available. Native species are then having to compete for those limited resources and are often out competed, leading to fewer and fewer of those native species.

The carp are transported to Ramsey Creek Park by a large truck with multiple water tanks containing the grass carp. Next a large hose is attached to one of the 10 holes on the bottom of the water tanks located on the side of the truck. After hooking up the hose securely to the water tank, the opposite end is lain out into the lake far enough so that when the carp come out they will be in water deep enough for them to swim in. It is important that the hose is set straight so the carp do not get stuck halfway through their journey from tank to lake. The carp are then released from the tank and rapidly slide down the hose all the way into the lake where they begin to cluster up as a seemingly endless number of carp exit the hose. It takes them a few minutes to orientate themselves and recover after their long car ride and short slide to freedom. They slowly but surely disperse into their new home, Lake Norman. This process is repeated for all the tanks situated on the back of the truck. While more carp take the slide from captivity to open waters, some of the grass carp that have already recovered can be seen a little further out jumping out of the water and splashing about enjoying their new-found freedom.

DCIM100MEDIADJI_0132.JPG
Hose that carp use to get from truck to lake at Ramsey Creek Park

Wouldn’t adding the grass carp do the exact same thing to the ecosystem as the hydrilla? The carp are sterile which means that they cannot breed. The grass carp help combat the hyrdilla which in turn helps native species return to the area. The stocking of sterile grass carp on Lake Norman is a cooperative effort with the NC Department of Environmental Quality (NC Aquatic Weed Program), NC Wildlife Resource Commission, Duke Energy, Charlotte Water and the Lake Norman Marine Commission.

 

 

 

Lake Management for Aquatic Weeds – Hydrilla

Charlotte Water owns and operates two drinking water intakes as the water supply for our community; one at Lake Norman and another at Mountain Island Lake. Aquatic weeds can pose a nuisance to water suppliers at their drinking water intakes by clogging pumps or as a biological contaminant that must be treated. There are a variety of ways to manage aquatic weeds. Complete eradication is often impossible but suppression is achievable.

HYDRILLA

Hydrilla is a non-native aquatic plant that forms nearly impenetrable mats of stems and leaves at the surface of the water. Like many non-native species, Hydrilla crowds out other vegetation and grows rapidly. It was introduced in the U.S. decades ago as an aquarium plant but has taken over many water reservoirs nationally through accidental release. Its growing season is spring and summer; it is dormant mid-fall through the winter.

 LAKE NORMAN & MOUNTAIN ISLAND INFESTATION STATUS

Though Hydrilla in local waterways has been managed for many years, annual biological controls have not been adequate to keep up with this season’s growth of the aquatic weed. Particular coves on Lake Norman are overwhelmed with the aquatic weed.

SUPPRESSION METHODS

Biological – Grass Carp

The typical method of managing Hydrilla in Lake Norman and Mountain Island Lake has been to stock coves with the Grass Carp fish. Periodically, tens of thousands of Grass Carp are released so that they may digest Hydrilla and keep the aquatic weed suppressed. The last batch of carp was released into Lake Norman in May 2018 in partnership with the Lake Norman Marine Commission, Duke Energy, Charlotte Water, and the NC Department of Environmental Quality (DEQ) in consultation with the NC Wildlife Resources Commission.

Chemical – Aquatic Herbicide

Specially formulated herbicides designed for application in water may also reduce the Hydrilla infestation. For herbicide application to be most effective, it must occur during the growing season (spring, summer) and by a licensed pesticide applicator.

Physical – Machinery Dredging

Machine dredging of the lake bottom is possible, but Hydrilla grows to depths of approximately 10 feet. Due to the cost and likely subsequent erosion, the use of heavy equipment to dredge or rake Hydrilla is not suggested. Also, mechanical control of Hydrilla only provides temporary relief and likely spreads the weeds to other areas of the lake through the release of plant fragments.

UPCOMING MANAGEMENT ACTIVITIES

At this time, Charlotte Water, Duke Energy, the Lake Norman Marine Commission, Charlotte-Mecklenburg Storm Water Services, and NC Department of Environmental Quality are relying on increased biological methods to suppress the weed. The group plans on releasing additional Grass Carp fish in the spring.

This method takes time but can be effective. In addition, the growing season for Hydrilla ends in the early fall, and the weed will go dormant.

We are encouraging residents to give the Grass Carp fish the time they need to ingest the weed.

In order to determine the number of Grass Carp fish that will be released in the spring, researchers at NC State will be surveying Lake Norman in the next couple of months to get an accurate acreage of Hydrilla.

FAQs

Can I apply an herbicide in waters adjacent to my property? 

If residents plan on applying an herbicide please contact a qualified, licensed aquatic applicator to apply an herbicide approved by the EPA for use in aquatic settings. Please note that stakeholders from Charlotte Water, Duke Energy, the Lake Norman Marine Commission, Charlotte-Mecklenburg Storm Water Services, and NC Department of Environmental Quality do not advise property owners use this method.

What steps will be taken to protect the community from any negative impacts of applying the herbicide?

If property owners use herbicides, Charlotte Water is requiring all applications of herbicide be applied at least one quarter mile away from drinking water supply intakes. The herbicide used should be approved for use in aquatic situations to protect aquatic life in the area.

ONLINE RESOURCES