Thurmond Lake hydrilla infestation expanding

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A tenacious aquatic weed first found in Thurmond Lake in 1995 has continued to expand and now infests about 60 percent of the reservoir’s 1,200-mile shoreline, according to a new study by the Army Corps of Engineers.

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Biologist Ken Boyd uses a special rake on a rope that he casts out into the water to get samples of hydrilla plants from Thurmond Lake.  MICHAEL HOLAHAN/STAFF
MICHAEL HOLAHAN/STAFF
Biologist Ken Boyd uses a special rake on a rope that he casts out into the water to get samples of hydrilla plants from Thurmond Lake.

“It started, we think, around Cherokee boat ramp,” said Scott Hyatt, the operations project manager at the lake.

The weed, hydrilla, likely arrived from some other infested body of water aboard a boat propeller.

“Now it’s along most of the shoreline, 60 percent or more, from the edges out to 15 or 20 feet,” he said.

Although efforts have been made to control the weed through spot herbicide treatments, the link between hydrilla and deaths of bald eagles and other birds has led some wildlife authorities to call for more drastic control measures.

In certain environments, including Thurmond Lake, hydrilla harbors an unusual algae that is believed to produce a neurotoxin ingested by small birds known as coots that are a favorite food of bald eagles.

The condition, known as avian vacuolar myelinopathy, or AVM, creates brain lesions that have killed at least 60 eagles at Thurmond Lake and many more elsewhere.

Controlling hydrilla could be one step to reducing AVM outbreaks, but any solution could be controversial, and also expensive.

One option under review is the introduction of sterile grass-eating carp. Such a plan, however, might be opposed by anglers who enjoy better fishing around the dense mats of hydrilla.

“These fish are basically goats with gills, and they can grow to 40 pounds or more,” Hyatt said.

The carp have been used successfully in other lakes, including Walter George in west Georgia.

Concerns about using carp include the cost. It would take about $500,000 spread over several years to place the needed number of fish into the lake.

Carp are voracious feeders that would also eat native vegetation, so their impact on other aquatic plant species is uncertain.

Now that a new shoreline assessment has defined the extent of hydrilla infestation, the next step will likely involve a public perception survey managed by University of Georgia researchers to gauge whether there is enough public support to undertake a carp stocking program.

That survey, which will target stakeholders such as anglers and lake-area property owners will be launched next year.

Later, a formal environmental assessment might be required, Hyatt said.

“We could just broaden the chemical treatments we do now, but that only works in certain areas,” he said. “Carp are the only means to completely control it in all the areas.”

The corps will continue to work with stakeholders and resource agencies in Georgia and South Carolina and hopes to devise a plan of action within 18 months.

“That is the goal,” he said. “But there are a lot of variables that could come into play in that 18 months – and from then on out, it would still be funding dependent.”

The shoreline assessment found hydrilla in all major portions of the lake except the western end of Little River and the extreme northern end of the reservoir closer to the Russell Dam tailrace.

ABOUT HYDRILLA

Hydrilla, an exotic weed used in the aquarium trade, was first found in Thurmond Lake in 1995, when it covered just a few acres.

A new survey found the weed has infested about 60 percent of the lake’s shoreline areas.

The weed harbors a previously unknown algae species that is believed to produce a neurotoxin that can be fatal to eagles and waterfowl.

The condition, known as avian vacuolar myelinopathy, or AVM, has killed at least 60 bald eagles at Thurmond and many more elsewhere.

AVM creates lesions, or open spaces, in the brains of infected birds, causing erratic behavior and eventually death.

Small birds called coots, which eat hydrilla, are a frequently affected species. Coots are eaten by eagles, which in turn become affected.

Scientists are considering the introduction of sterile grass carp that would eat hydrilla and could reduce eagle mortality.

Sources: University of Georgia; Army Corps of Engineers

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Riverman1
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Riverman1 11/17/11 - 06:45 pm
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It's in the Columbia County

It's in the Columbia County portion of the river known as Stevens Creek Lake also. Another reason to keep sufficient flows in the river.

Willow Bailey
20603
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Willow Bailey 11/17/11 - 10:02 pm
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It is truly a problem, maybe

It is truly a problem, maybe we could have a community "Carp Drive".

Crime Reports and Rewards TV
33
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Crime Reports and Rewards TV 11/18/11 - 01:09 am
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Carp works they're sterile so

Carp works they're sterile so they go away after they eat up all the Hydrilla, or we can use golf cart tires rolling against each other in a line that farmers use to yank out weeds over their crops. Works wonders. Right now the river is choking on hydrilla and building up sand bars all over. There we should use the yanking tires to pull that real fast so the current can deepen the river in time for the drag boat races. Otherwise if we are little shy on water there won’t be a drag boat race there unless they want to drag race across sand bars:o)

Jane18
12332
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Jane18 11/18/11 - 08:04 am
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I found no enjoyment fishing

I found no enjoyment fishing anywhere hydrilla was growing, and neither did my husband. Why is the Corp of Enigineers not out on the lake now, getting rid of the grass that is on the "new" shoreline, since the levels have gone down so drastically? I forgot for a moment, they are thinkers, not doers(probably below their pay scale............)

southern2
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southern2 11/18/11 - 10:10 am
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Agree Jane18, they will wait

Agree Jane18, they will wait until it reaches full pool then lower it for maintenance like they did on the present DAM work. The lake has only been at full pool (330') for 49 days in the last 6 years. Well done ACOE.

Vito45
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Vito45 11/18/11 - 10:22 am
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Who gives a rip if people

Who gives a rip if people want to fish around it? It isn't a native plant , so the fishermen just need to get over it. And Jane, yes, now is the perfect time to use the herbicides in the shallow coves.

Rob Pavey
552
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Rob Pavey 11/18/11 - 10:46 am
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low lake levels help control

low lake levels help control hydrilla but it bounces back when the reservoir refills. last winter - when the lake was full - there was more hydrilla and they picked up 11 dead eagles. I suspect (hope) there will be fewer dead eagles found this season, with lower water. the corps uses herbicide almost every year but the spot treatments are only done around selected boat ramps. carp might work, but they are expensive - $300,000 to $500,000 spread over several years. To put it in context, though, the herbicide program they use at Lake Seminole costs almost that much - each year. I also wonder, if they put all those carp in clarks hill, and they grow to their usual size, if the bow fishermen would be willing to let them do their job before they are removed. A 30-pound carp is a tempting target.

kip0366
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kip0366 11/18/11 - 02:16 pm
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Rob- Please state all the

Rob- Please state all the facts. Your article states the Algae is believed to produce the neurotoxin, but the link between the Algae and the deaths of Eagles is an assumption and has not been scientifically proven. The fact is that the coots are transferring the AVM to the Eagles, but scientists are not sure how the coots are being infected. The algae on the Hydrilla are just one theory.

The introduction of an exotic species to control an existing exotic species has had limited success, and has caused many negative impacts on the ecosystem. The Asian Carp that have been introduced are larger and more voracious eaters than native carp causing native species to decline drastically. Research Santee Cooper lake (and others the carp have been used on), the carp were introduced, consumed all the hydrilla as well as any native aquatic plants. These sterile carp also reproduced somehow, and now they are dealing with low fish reproductive rates, the carp have destroyed habitat that other fish use to spawn.

The St Johns River system in Florida had the hydrilla eradicated in the 1980's using herbicides. The amount of chemicals required to destroy the hydrilla almost destroyed the entire ecosystem.

As with any exotic species there are usually good impacts and bad impacts.
On the plus side:
The hydrilla does clean and add oxygen to the water. The Corps had been studying placing oxygen systems similar to the one at Russell. It provides a hiding place for smaller and yearling fish contributing to larger populations of fish. For a comparison, look at the lakes on the Tennessee River, these are some of the most productive fisheries in the nation and all have hydrilla and/or milfoil exotic grass.

On the negative side:
It is a non-native species. It will completely choke out smaller coves, especially those less than 10 feet deep, limiting access and recreation. It may have harmful algae.

There are alternatives, mechanical removal is possible. This method does not require chemicals or non-native species. This will also allow for selective harvest, so that some of the benefits can be retained. The TVA has been using this method for years, as well as the Florida DNR.

Let's not cause more problems by assuming or introducing more exotic species.

Little Lamb
46885
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Little Lamb 11/18/11 - 02:45 pm
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Excellent post, kip. I

Excellent post, kip. I particularly got a kick out of this:

There are alternatives, mechanical removal is possible. This method does not require chemicals or non-native species. This will also allow for selective harvest, so that some of the benefits can be retained. The TVA has been using this method for years, as well as the Florida DNR.

Corps of Engineers? Mechanical harvesting? Are you kidding? They can't even be bothered to turn a few switches to manage flow from the dam to balance the interests of competing user. They just want to set the flow on autopilot. To expect them to manage hydrilla is outside their perceived job scope.

yu nah ee tah
31
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yu nah ee tah 11/18/11 - 02:55 pm
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Anyone wanting to know the

Anyone wanting to know the latest and straightest need only put "Susan Wilde UGA hydrilla AVM" in their search engine and read. There is much misinformation out there and in these comments, for example, the hydrilla does provide structure for fishing but then when the hydrilla gets real thick, it actually LOWERS oxygen levels and we know what that does to all fish.

And please consider that Henri-Christophe Bouget got tangled up in hydrilla and drowned in Clayton County in October 2010. Go to the Atlanta Journal website and read for yourself. Lake Spivey had to be drained so the divers could find the body. Dr. Susan Wilde was called in to evaluate the problem. Clayton County immediately put in grass carp but that was little consolation to the Bougets.

catfish20
272
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catfish20 11/18/11 - 03:37 pm
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I own a home on the lake and

I own a home on the lake and have been screaming about the hydrilla issue for years. There have been extensive studies done by the Corps of Engineers and numerous universities using chemical treatments, sterile carp and manual removal. Manual harvesting is the least effective method of removal. You may temporarily remove the hydrilla from your waterfront but those little pieces of hydrilla that floated off during the process do not die. Instead, they float around until they find a new home. This new home may be your property or it may be your downstream neighbors property where it takes root and grows. We need to use a combination of chemicals and carp. The studies recommended chemicals that would not harm the environment or critters. Carp are an extremely effective method of removing hydrilla. In addition to the deceased eagles, we need to consider the damage hydrilla does to props and swimmers who become tangled in the plant. Fishermen used to fish around my dock every morning and evening. However, the area around my dock now has a heavy canopy of hydrilla and I no longer see the fishermen. It is way past time for the Corps of Engineers to act.

ganurse
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ganurse 11/18/11 - 03:47 pm
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I hear moose eat it... That

I hear moose eat it... That would be fun to watch!

Vito45
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Vito45 11/18/11 - 05:24 pm
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I have a friend on lives on a

I have a friend on lives on a lake in Fla that had a hydrilla issue. They put carp in it and they took care of it, just too well. They ate absolutely every piece of vegetation in the lake and essentially sterilized it. It was strange walking around the shoreline and seeing nothing but water and the bottom.

yu nah ee tah
31
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yu nah ee tah 11/18/11 - 06:32 pm
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The carp will indeed eat

The carp will indeed eat everything. The truth about Clark Hill is that there is, compared to other lakes, relatively little native aquatic vegetation. The three governments - US, Ga and SC need to budget enough money on top of the $500k to survey the lake to determine what does grow well here. Then take samples and propagate those plants elsewhere and then when the sterile carp die, about 12 years, replant the lake with good native plants. This is a long term solution to a problem that did not develop overnight. The Corps already has this type program in place and a few more grad students/interns working on it is all it would take.

If you have ever watched a coot die of the Avian Vacuolar Myelinopathy brain lesions - helpless, spastic movements, flopping around in the water and imagined our national symbol, the bald eagle, suffering a similar death, you have to agree on grass carp, which are, in bench tests, immune to the epiphytic cyanobacteria. Eagles ingest a larger number of AVM-positive waterfowl resulting in quicker and more prevalent deaths.

I have heard the eagles' spine tingling screams in a territorial fight with each other and completely understand why our forefathers picked this magnificent bird of prey as our national symbol. Now bureaucratic bungling will kill them all. Clark Hill is the Bald Eagle Death Capital of the World.

jenn5225
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jenn5225 11/18/11 - 09:21 pm
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The economic impact of

The economic impact of hydrilla extends far beyond the spending of public funds on control measures and the immediate effects on sport fisheries and other aquatic activities. In the TVA system in September 1989, heavy late-season rainfall and consequent flood discharges
caused large mats of hydrilla to break loose. These mats clogged intake screens and forced the shutdown of two hydroelectric turbines at Guntersville Dam. Hydrilla mats floated over the spillway and blocked water intakes downstream at Wheeler Dam. The result was $170,000 in lost power plant revenues. Similarly, in June 1991 the St. Stephens hydroelectric plant on Lake Marion in South Carolina was shut down because of a hydrilla accumulation on the water intake screens. A study of Orange Lake in north central Florida concluded that the economic benefits associated with the lake and surrounding properties and businesses was almost $11 million annually. During the years when hydrilla covered most of the lake, however, the benefits were
almost negligible.

Vito45
-2
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Vito45 11/19/11 - 01:39 am
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I don't know where Orange

I don't know where Orange Lake is in Fla, but the one my buddy lived on was more or less east/northeast of downtown Orlando a few miles. I will look it up on google.
Edit- looks like Lake Fairview.

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