Barnett Reservoir board takes serious action to combat invasive giant salvinia Invasive aquatic plant threatens popular lake

Brian Broom | Mississippi Clarion Ledger

Show Caption Hide Caption Boat-damaging rebar removed at Rez Anglers have been marking stumps with rebar for decades at Barnett Reservoir, but the metal rods have become more of a problem than the submerged trees and stumps themselves. So, Rez personnel are removing the rebar from the lake.

It was something no one wanted to hear, but giant salvinia was recently found in Pelahatchie Bay at Barnett Reservoir and the Pearl River Water Supply District has declared the situation an emergency.

“We’ve been advised that we have an opportunity to eliminate giant salvinia in Barnett Reservoir, but only if we take actions now to contain the plant to the Pelahatchie Bay area,” said Barnett Reservoir general manager John Sigman. “To do that, we have developed an action plan that we know will not be popular with all our users and residents, but we feel is necessary to control and possibly eradicate giant salvinia.”

The plant is aquatic and it is both highly invasive and non-native. It is feared that if left unchecked it could take over parts or all of the popular lake. In an effort to eradicate it, the reservoir board of directors approved three measures — a temporary ban of all boating on Pelahatchie Bay, continued extensive herbicide treatment and lowering the lake level during the winter months to expose the plant to its environmental weakness, cold weather.

Effective October 19, all boat ramps in the Pelahatchie Bay area will be closed to prevent the spread of the plant by boat. Giant salvinia has been shown to be viable for a week out of the water and even longer in a moist environment such as a boat’s bilge or on a carpeted bunk board on a trailer.

The boating ban includes all types of watercraft including fishing boats, pleasure craft, canoes, kayaks, personal watercraft, and sailboats. Only vessels owned by governmental agencies and PRVWSD-approved contractors will be allowed on Pelahatchie Bay during the closure.

Passage between the main lake and Pelahatchie Bay under the bridge of Northshore Parkway will be blocked with temporary booms. The booms are designed to block the plant from riding wind or current from the Bay to the main lake, as well as on boats or their attachments.

Residents with waterfront leases who have docked boats will have until November 5 to remove their boats at Pelahatchie Shore Park if they choose to do so.

The winter draw-down is considered a critical part of the plan. According to reservoir officials, the plant has little tolerance of cold temperatures. So, it could be the best chance of eradicating it.

“A cold winter, combined with low water levels, intensive herbicide application, and containment gives us an opportunity to eradicate giant salvinia this winter,” Sigman said.

To some the actions may seem like overreactions, but reservoir consultant Bobby Cleveland said giant salvinia is a major threat.

"Once it takes over an area like a cove or a bay like Pelahatchie Bay it pushes out all the native vegetation," Cleveland said. "It's a thick mat so no sunlight hits the bottom."

Cleveland said it also reduces the level of dissolved oxygen and can make an area unsuitable for fish.

"Once it gets started and takes over an area you can't fish there, fish can't survive there and you can't kill it."

Cleveland said the the plan currently is to draw down the lake from its normal 297.5 feet to 295.5 feet, but that may not always be possible due to rain and potential impacts downstream.

"We're looking at being down by December 1 and remaining down in January and February," Cleveland said. "Those are the months we generally have the best chance of having consecutive days of subfreezing temperatures."

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