NC INVASIVE PLANT COUNCIL
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Eno River Hydrilla Management Project

 Photo below shows Pleasant Green access site during the height of the Hydrilla infestation (2014)
Picture

The content on this page has been provided by the
Eno River Hydrilla Management Task Force


The purpose of this page is to serve as a centralized location for information specific to the Eno River Hydrilla Project.  The information ranges broadly from very general documents and updates to highly technical reports. 

Beginning in 2020 Eno River project information will transition to a new website.  Thank you to NC-IPC for providing a home for this project on their website for all of these years!  Going forward the NC Aquatic Weed Control Program website will become the primary site for the most up to date information. Click
here.
 
This webpage will not be deleted and serve primarily as an archive.

Managing Hydrilla with herbicide in the main stem of the Eno River 

2019 herbicide treatment summary:
An herbicide treatment (fluridone) started on June 17th and continued through August 15th.  The herbicide was metered into the river using an injector system, which was routinely readjusted to match the flow of the water.  The section of the Eno that was treated is defined by the Lake Ben Johnson dam in Hillsborough and downstream to Lawrence Road bridge in Hillsborough.  This is a shorter stretch of the river compared to previous treatment targets.
No Hydrilla was observed/reported within the treatment area in 2019.


2018 herbicide treatment summary:
An herbicide treatment started on May 24th and continued through August 15th.  This was essentially a repeat of the treatment that was done in 2017.  The section of the Eno that was treated is defined by the Lake Ben Johnson dam in Hillsborough and downstream to the Roxboro Street bridge in Durham.  The herbicide (fluridone) was applied by two injection systems.  Each system precisely metered the herbicide product and was routinely adjusted to match the flow of the river.  Monitoring efforts occurred throughout the season; no negative impacts to the environment were observed/reported.  Water samples pulled from the treatment area on August 28th were analyzed for herbicide levels and all samples were found to have <1 part per billion (ug/L) fluridone.  This is equivalent to 'no detect' levels. 
No Hydrilla was observed/reported within the treatment area in 2018. 

2017 herbicide treatment summary:
An herbicide treatment started on June 30th and continued through August 15th.  Since the first two years of managing Hydrilla with herbicide had been very successful the ERHM Task Force decided to expand the treatment area in 2017.  The area that was treated in 2015-2016 was included in the treatment.  The change in 2017 was that the treatment area was expanded upstream to just below the Lake Ben Johnson dam.  Similar to 2016, two injection systems were used to meter herbicide into the river. 

2016 herbicide treatment summary:
The treatment area and herbicide product remained consistent with the 2015 treatment. The herbicide product was metered into the river using two injector systems. The addition of a second injector system (located approximately midway through the treatment area) allowed for better control of the target concentration and allowed for a reduction in the total quantity of herbicide needed. The herbicide treatment did not prohibit, or impact in any way, recreational activities such as wading and swimming nor did it impact fishing or fish consumption. The treated water remained fit for consumption by animals (livestock, domestic pets, wildlife, etc.).

2015 herbicide treatment summary: 
An aquatic-use herbicide was used to treat a section of the Eno.  A liquid formulation of fluridone was metered into the water at a single location.  The treatment began in June and ended in August.  The treatment effectively controlled the growth of Hydrilla throughout the ~16 mile long stretch.  The treatment area defined as the Lawrence Road bridge (just downstream of Hillsborough) and down to N. Roxboro Street (north of Durham).


Brief description of the Eno River and 
history of Hydrilla within the watershed

The Eno River is a relatively shallow, swift flowing, Piedmont stream originating in northwest Orange County.  It forms at the confluence of the West Fork Eno River and the East Fork Eno River and flows eastward through Durham County where it joins the Flat River to form the headwaters of the Falls Lake Reservoir.  From its origin to Falls Lake the Eno flows approximately 28 miles and encompasses an approximately 150 square mile watershed area. 
Previous to 2005 the only known Hydrilla infestation within the Eno watershed was Lake Orange.  Lake Orange was confirmed as a Hydrilla site in 1992.  The lake was stocked with triploid grass carp in 1994 and also in 1998 for the purpose of removing the invasive plant.  Hydrilla was thought to be eradicated from Lake Orange by 2005. 
In 2005 Hydrilla was observed growing in a section of river within the Eno River State Park boundaries.  Since 2005 Hydrilla has been reported in several locations along the the Eno River Between Hillsborough and Roxboro Road in Durham.  Including many of it's impoundments; specifically, Corporation Lake, the West Fork Eno Reservoir, Lake Orange and Comptons Pond.


Eno River Hydrilla Management Task Force


The Eno River Hydrilla Management Task Force (ERHM TF) is a partnership of government agencies, academia and non-profit organizations (see list to right).  The partnership is composed of aquatic vegetation management experts, environmental managers, stakeholders and environmental stewards.  The ERHM TF serves as a project oversight group and is composed of four committees (Outreach, Research and Monitoring, Funding, and Public Health).  The idea of assembling a task force emerged in November of 2012 when several agency representatives met to discuss the continuing and worsening spread of the invasive weed Hydrilla within the Eno River.  The ERHM TF began to coalesce to include the many partners now represented and has met roughly twice per year since 2013. 

Please direct any questions or comments you have about the Eno River Hydrilla Management Task Force:

Rob Emens   
rob.emens@ncdenr.gov

  • City of Durham
  • City of Raleigh
  • Durham County
  • Eno River State Park
  • NC Dept. of Agriculture & Consumer Services
  • NC Dept. of Health and Human Services
  • NC Division of Parks & Recreation
  • NC Division of Water Resources
  • NC Natural Heritage Program
  • NC State University
  • NC Wildlife Resources Commission
  • Orange County
  • Town of Hillsborough
  • Triangle Fly Fishers
  • US Army Corps of Engineers
  • US Fish & Wildlife Service

What can be done to slow the spread of Hydrilla?

  • Educate yourself and others on Hydrilla 
  • Report sightings of Hydrilla to Eno River State Park staff
  • Don't be a vector....  Clean, Drain, Dry is a great managment practice, see below:
  1. Remove, brush and wash any visible mud, plants, other debris before transporting equipment/gear.
  2. Check your fishing pole, gear and bait bucket for plants, mud or debris. 
  3. Clean your canoe/kayak storage compartments, rigging, etc.
  4. Drain water from buckets, live wells, bilge, etc.
  5. Let equipment completely dry out prior to using at another site.

Picture

Picture

Hydrilla (Hydrilla verticillata )
Key Characteristics to look for:

• Leaflet Number: 3-10 leaves per whorl • Leaf Margin: Finely serrated
• Leaf/Leaflet Shape: Oblong
• Leaf Length: 1/3– 1/2 inch 

Hydrilla Facts

• A fragment of hydrilla (as small as 1" long) can grow into a new plant
• Hydrilla is an exotic species (native to Asia)
• Hydrilla is considered one of the worst aquatic weeds in the United States
• It is illegal to transport hydrilla; federal and state laws prohibit the culture, sale, distribution, etc. 
• Hydrilla grows as a submersed plant, only parts of the plant will reach the surface of the water

Effects of Hydrilla 

• It has the potential to negatively impact fish communities
• Interferes with recreation (boating, fishing and swimming)
• Harmful to native aquatic communities 
• Reduces water flow
• Loss of property values and tourism
• Harbors toxic cyanobacteria that leads to bird deaths 

Management Strategies

Herbicide applications in summer.
          Selected herbicides are:
                    • Approved by the EPA for aquatic sites
                   
• Pet safe / non-toxic to fish
                    • Do not restrict recreational activity at application rates

Citizens and wildlife/environmental managers play a critical role in preventing, detecting and reporting new infestations.  If you have found a plant you believe could be Hydrilla please contact Rob Emens (NC Division of Water Resources).
rob.emens@ncdenr.gov   919-707-9012


Point of Contact:

Eno River State Park 
919-383-1686 
eno.river@ncparks.gov 
Eno River Hydrilla Brochure
File Size: 817 kb
File Type: pdf
Download File


Document Links

ENO RIVER HYDRILLA
FACTSHEET (one page)

FACTSHEET (full version)

 A BRIEF OVERVIEW OF HYDRILLA WITHIN ENO RIVER STATE PARK
NC Dept. of Health factsheet on the Eno River hydrilla control project
PUBLIC HEALTH EVALUATIONS FOR POTENTIAL EXPOSURES TO HERBICIDE
ENVIRONMENTAL 
ASSESSMENT FOR CONTROLLING HYDRILLA IN THE 
ENO RIVER WATERSHED

Other Documents 

 (RESEARCH - NEWSPAPER ARTICLES - SURVEY REPORTS)

Using Herbicides to Save Endangered Snails; Scientific American, July 20, 2018
UGA researchers identify, name toxic cyanobacteria killing American bald eagles; UGA Today, February 18, 2015
Eno River Aquatic Vegetation Survey; City of Durham, January 2014

Other Web Resources

NCDEQ Aquatic Weed Control Program
NCSU - Crop Science - Aquatic Plant Management
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  • Home
  • About
    • Donate
    • Invasives 101
    • Membership
    • Board of Directors >
      • NC-IPC ByLaws
    • Contact
    • Listserve
  • News
    • Iverson Scholarship
    • Wildland Weeds Magazine
    • Calendar >
      • 2018 Workshop
  • NC Invasive Plants
    • Ailanthus Altissima (Tree-of-Heaven)
    • Elaeagnus umbellata (Autumn Olive)
    • Ficaria verna (Fig Buttercup)
    • Imperata cylindrica (Cogongrass)
    • Ligustrum sinense (Chinese Privet)
    • Ligustrum vulgare (Wild Privet)
    • Lonicera japonica (Japanese Honeysuckle)
    • Microstegium vimineum (Japanese Stilt Grass)
    • Nandina domestica
    • Nymphoides indica (water snowflake)
    • Paulownia tomentosa (Princess Tree)
    • Persicaria perfoliata (Mile-A-Minute Vine)
    • Pueraria montana (Kudzu)
    • Pyrus calleryana (Bradford Pear)
  • Annual Symposiums
    • 2022 Joint Symposium >
      • 2022 Speaker Presentations
    • 2021 Virtual Conference
    • 2019 Joint Symposium >
      • 2019 Presentations
    • 2018 Annual Symposium
    • 2017 Annual Symposium
    • 2016 Annual Symposium >
      • 2016 agenda
    • 2015 Annual Symposium >
      • 2015 Presentations
      • 2015 Agenda
  • Projects
    • Fig Buttercup Project
    • Eno River Hydrilla Project
    • Awareness Week
  • Awards
    • 2015 Student Competition Winners
    • 2015 EIA Award
    • 2014 EIA Award