Adopt-A-Carp :: Lake Norman Hydrilla Control Project

Hydrilla growing under a dock.
(Photo courtesy of Lake Norman Cove Keepers.)

What is Hydrilla? Why is it harmful?

Crowds out beneficial native vegetation
Blocks irrigation and drainage canals
Increases sedimentation in flood control reservoirs
Interferes with public water supplies
Harbors the vectors of human and animal diseases
Impedes commercial fishing and navigation
Blocks docks, marinas, and boat launching sites
Makes recreational activities such as swimming, boating, skiing, and sport fishing difficult and dangerous if not impossible

Hydrilla came to Lake Norman in one of several ways. It is possible that someone could have planted hydrilla in an effort to create bedding for fish. It is also possible that someone could have picked up hydrilla from one of the other lakes via their boat prop only to have it be released into Lake Norman.

Hydrilla is spread by having the weed picked up by water vessels and deposited in other parts of the lake. It is strongly recommended that you inspect your boat each time to you use it and remove hydrilla, or any other weed, found. Do not throw any weeds back into the water.

Hydrilla can infest an entire lake making it unsuitable for other forms of life to exist in the lake.
(Photo courtesy of Duke Power.)

Why should the Lake Norman Community be concerned?

Extensive hydrilla growth will eliminate or seriously reduce traditional shallow water (down to 10 or more feet) recreational activities such as boating, swimming, and fishing. The aggressive growth of the plant could potentially result in fish kills if portions of the beds die-off. Plant decomposition following die-off lowers dissolved oxygen of the lake water below the level needed by fish and other aquatic life. Plant decomposition may also produce taste and odor problems for water suppliers.

Cowan's Ford Dam and Marshall Steam Plant supply power to Duke Power Company. The lake also provides a large portion of this area's drinking water. Potential blockage to water intake pipes for both potable water use and power production is a major concern to the water departments of the five counties surrounding Lake Norman, as well as Duke Power Company. The plant is not yet causing problems to these operations.

Hydrilla can become entangled in boat propellers and destroy the motor and drive shaft.
(Photo courtesy of Duke Power.)

Is it being taken seriously?

As a result of the impact on our power and water source, the issue is being given a very high priority. Various agencies in both North and South Carolina are coming together to formulate a long-term management plan for the plant throughout the Catawba River Basin. Developing and implementing such a plan could take a few years. Everyone should be made aware of the plant, itís adverse impact on our environment and take appropriate steps to help control the growth.

Chemicals are not being considered at this point for use against hydrilla in Lake Norman. Sterile Grass Carp are being stocked in the lake. The Grass Carp feed specifically on submerged aquatic plants and especially enjoy hydrilla. As of summer 2004, there are 6,000 grass carp stocked in the lake and another 1,500 will be needed each year to keep up with the growth of hydrilla and to replace fish that have died off over the previous season. The North Carolina Wildlife Resources Commission-Fisheries suggests as many as 20 grass carp per vegetated acre could be stocked. The Commission ultimately makes the decision on how many carp will be stocked. It is estimated that there is approximately 1200 acres of potential hydrilla habitat in the lake. One caution: the fish eat most species of submerged aquatic plants; however, there is no native vegetation under Lake Norman as the area was landscaped clean before the lake was filled.

It may take several years before the grass carp begin reducing the hydrilla population.

Should you catch a grass carp, it should be released immediately.
(Photo courtesy of the Marine Commission.)

What should I do if I catch a grass carp?

You should immediately release the fish back into the water. The Lake Norman Marine Commission passed an ordinance in September 2004 making possession of the Sterile Asian Grass Carp illegal. This ordinance is enforceable by all state, county and city authorities that patrol Lake Norman. The ordinance was passed because each Sterile Grass Carp costs between $ 5.00 to $ 12.00 each. For each fish caught is another fish that we must replace.

Yes. The entire Catawba River Basin is in jeopardy. Lake James is having significant problems (see http://www.ljea.org/hydrilla.html#sum). Mountain Island Lake is also infected. State natural resource agencies in both NC and SC are discussing various hydrilla management options with area reservoir managers such as Duke Power. These discussions are directed toward developing a Catawba River basin wide Hydrilla management strategy.

Unfortunately, no. The plant has little nutritional value as 98% of it is water. There have been no research showing successful use of the plant for anything (beyond feeding aquatic plant eating fish like Carp).

If you are a lake lot owner and have beds of Hydrilla either starting or well underway, it would not hurt to go ahead and use a rake to pull it up and out of the water. Only clear areas that are critical to your use. Clearing large areas is extremely tiring and difficult due to weight of the wet material. Try to rake as close to the root as possible. It will be difficult to pull the tubers out of the lake bottom so anticipate the plant growing back. To dispose of the plants you remove, scatter the plant on land and simply allow the plant to dry. As it is 98% water, you will be left with straw to rake up. It is not recommended to bag the weed as that will only keep in moisture. Get comfortable with the fact that the plant is here to stay. We just need to ensure we implement appropriate management techniques. Everyone should contact the Lake Norman Marine Commission to express your concern over this problem.