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Hydrilla verticillata (hydrilla), an invasive
<br />species of aquatic weed native to Asia, clogged
<br />the Eno River in Orange and Durham. Hy-
<br />drilla is being treated by an aquatic herbicide
<br />in an effort to reclaim the river for recreation.
<br />"Treatment is going well. We're seeing the
<br />growth of hydrilla being suppressed by the
<br />herbicide. You won't see thick mats on. the
<br />river like you have in the past several years,"
<br />said Rob Emens, Eno River Hydrilla Manage-
<br />ment Task Force leader.
<br />These mats have negatively impacted fish-
<br />ing, wading and swimming in the river, he
<br />said, adding, "We're restoring recreation on
<br />the river this year.
<br />Hydrilla was transported to the U.S. as an
<br />aquarium plant around 1960 and has now spread
<br />into all the Gulf Coast and South Atlantic states
<br />as far north as Delaware. It grows quickly, re-
<br />produces easily and creates nearly impenetra-
<br />ble mats of stems and leaves on the surface of
<br />lakes, rivers and other waterways. It is a high-
<br />ly destructive plant that reduces water flow
<br />and quality, crowds out native aquatic Vege-
<br />tation, enhances mosquito breeding and har-
<br />bors toxic cyanobacteria that harm waterfowl
<br />and predatory birds.
<br />Hydrilla clogs water intakes in rivers and
<br />reservoirs that are used for drinking water sup-
<br />plies and irrigation and can make boating, swim-
<br />ming and fishing difficult, if not impossible.
<br />It is regulated by the federal and state govern-
<br />ments; it is illegal to transport, grow or sell.
<br />Hydrilla was first discovered in the wild
<br />in North Carolina in 1980 at Umstead Lake
<br />in Wake County, as well a few other Wake
<br />County lakes: Lake Lynn Park, Fred G. Bond
<br />Metro Park in Cary and Lake Wheeler Park,
<br />Raleigh. In 1983, a herbicide was first applied
<br />to Umstead Lake. In 1984, the first applica-
<br />tion of herbicide was used at Fred G. Bond
<br />Metro Park.
<br />One year later, sterile grass carp were intro-
<br />duced into Lake Wheeler. These carp selec-
<br />tively eat hydrilla. That introduction went well
<br />—the carp removed the hydrilla quickly and
<br />then the carp population died off.
<br />In the 1992, hydrilla was first found in the
<br />Eno River basin in Lake Orange, just north of
<br />Hillsborough. Grass carp were introduced into
<br />Lake Orange in 1994 and again in 1998. For
<br />several years, there were no carp and there
<br />was no hydrilla. Unfortunately, there was some
<br />hydrilla in the shallow water where the carp
<br />couldn't get to.
<br />In recent years, hydrilla has been showing
<br />up in the head waters of Lake Orange. In 2009,
<br />researchers confirmed hydrilla in another up-
<br />stream reservoir, West Fork Eno Reservoir. The
<br />NC Division of Water Resources is actively
<br />managing hydrilla in both upstream reser-
<br />voirs.
<br />Surveys conducted in 2013 and 2014 found
<br />hydrilla throughout the Eno River basin: in
<br />-25 miles of the Eno River, the West Fork Eno
<br />Reservoir, Arrowhead Lake (near Lake Orange),
<br />Rob Emens and Drew Gay of NC DENR Divi-
<br />sion of Water Resources Aquatic Weed Control
<br />Program doing maintenance on herbicide in
<br />jection station on the Eno. Treatments contin
<br />ue into September.
<br />PHOTO BY CAROLINE GILMORE
<br />and Corporation Lake (on west side of Hills-
<br />borough), spreading as far downstream as NC
<br />Highway 501 (Roxboro Road, Durham).
<br />Research by NC State University and the
<br />state park system suggests the hydrilla infes-
<br />tation of the Eno River is spreading downriv
<br />er at a rate of up to one mile per year, and if
<br />left alone, would reach Falls Lake, the largest
<br />source for Wake County's drinking water,
<br />within 12 years.
<br />The Eno Hydrilla Management Task Force
<br />was formed in 2007, two years after the re-
<br />emergence of hydrilla in the Eno River basin,
<br />to evaluate and address the infestation. The
<br />task force has 16 members with federal, state
<br />and local government representatives. It is
<br />chaired by Rob Emens of the Division of Water
<br />Resources, NCDENR, Aquatic Weed Control
<br />Program.
<br />Eradication of hydrilla is difficult because
<br />the plants can reproduce by tubers (subterranean
<br />root sections), turions (floating root sections),
<br />and plant fragmentation (leafy plant sections);
<br />can overwinter; and can survive dormant for
<br />six years or more.
<br />The Task Force evaluated the options avail-
<br />able for addressing the hydrilla infestation of
<br />the Eno River and decided on using aquatic
<br />herbicides. Since the Eno is a flowing water
<br />system instead of a contained water system,
<br />using aquatic herbicides was considered the
<br />best option.
<br />Two herbicides were evaluated: AQUA -
<br />THOL@ K (endothall) manufactured by United
<br />Phosphorus, Inc. and SONAR@ GENESIS (flur-
<br />idone) manufactured by SePRO Corporation.
<br />Both were approved by EPA for aquatic sites,
<br />are non -toxic to humans, pets and wildlife and
<br />do not require any restrictions on recreation-
<br />al activity when used at the approved applica-
<br />tion rates.
<br />}
<br />8 C' " 4
<br />After extensive research, the task farce
<br />decided fluridone was the safest herbicide.
<br />ERHMTF has been working with experts from
<br />SePRO to develop a two -year pilot program
<br />for the management of hydrilla in the Eno.
<br />A public information open house was held
<br />in April in Hillsborough for the public to learn
<br />more about the proposed pilot program. Pre -
<br />senters described the threat hydrilla poses and
<br />experts on hydrilla were available to answer
<br />questions.
<br />In May, the Task Force began using fluri-
<br />done upstream from Eno River State Park.
<br />Emens told "CSN, "This is the first time the
<br />state has treated hydrilla in flowing, system." z
<br />But it has been used for many years to effec-
<br />tively combat hydrilla in the contained' water
<br />systems of Lake Gaston, Lake Tillery, Lake
<br />Waccamaw and Tar River Reservoir.
<br />Herbicide treatments will continue to mid-
<br />September 2015. They are being done on 16.4°
<br />miles' of the Eno River, from Lawrence Road
<br />to NC Highway 501. Fluridone is continuous
<br />ly pumped into the river at one location via a
<br />computer - controlled pump that delivers her-
<br />bicide at a rate that is based on water flow'
<br />and results in a constant herbicide concentra-
<br />tion of 4 -5 parts per billion.
<br />"We're monitoring herbicide levels at four
<br />sampling points along the river," said Emens.
<br />Water samples are taken on a weekly basis.
<br />A cost of $75,000 per year was budgeted
<br />for the two -year pilot program being conduct-
<br />ed this summer and next.
<br />Flow 1 Stop
<br />Hydrilla spreads from one body of water
<br />to another primarily when plant fragments get
<br />caught on boats and trailers. How can we do
<br />to stop the spread of hydrilla? Educate your-
<br />self and others on hydrilla. beep your boat
<br />and gear clean.
<br />Don't transport aquatic nuisance species:
<br />Remove, brush and wash any visible mud,
<br />plants and other debris before transporting
<br />boats and equipment. Drain water from boat
<br />before going into another water body. Let boat/
<br />trailer /equipment completely dry prior to using
<br />at another site. Check your canoe or kayak stor-
<br />age areas; paddles and carry straps. Check your
<br />fishing pole gear and bait bucket for plants,
<br />mud or debris.
<br />Community Sports News
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