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Treatment to manage invasive Hydrilla resumes in Eno River

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Roy Cooper, Governor
Susi H. Hamilton, Secretary
Release Note: 
Katie Hall
Release Date: 
Friday, June 2, 2017

Treatment to manage invasive Hydrilla resumes in Eno River

DURHAM, N.C. — Herbicide treatment for an infestation of Hydrilla in the Eno River is underway and will last through September. Hydrilla is a highly destructive, non-native aquatic plant from Asia that grows rapidly, creating thick mats on the surface of lakes, rivers and other waterways, impeding recreational activities and the health of fish and wildlife in the area. The herbicide treatment follows a two-year pilot that significantly reduced Hydrilla without impacts to the rest of the ecosystem or to human health.

The Eno River Hydrilla Management Task Force, in cooperation with the N.C. Division of Water Resources’ Aquatic Weed Program and the N.C. Division of Parks and Recreation, hired SePRO Corp. to apply the herbicide Sonar Genesis® in a 16-mile target zone of the river from the Town of Hillsborough to Roxboro Road (N.C. Highway 501) in Orange and Durham counties. The herbicide will be applied in a concentration well below limits set by the EPA and is safe for humans, fish and wildlife. Property owners adjacent to the treated section of the river will be cautioned regarding the use of river water for irrigation during Hydrilla treatment.

“Pesticides approved for aquatic sites have passed a rigorous testing process. Fluridone is one of the least toxic among those,” said Rob Emens, program manager for N.C.’s Aquatic Weed Control Program. “At the rate it will be applied in the Eno, no restrictions on water use will be triggered except for irrigating certain plants and seedlings.”

Hydrilla was first discovered in the Eno River watershed in the early 1990s in Lake Orange, which is located upstream of Hillsborough. In 2009, biologists confirmed Hydrilla in another upstream reservoir, West Fork Eno Reservoir. The N.C. Division of Water Resources is actively managing Hydrilla in both upstream reservoirs. Hydrilla growth crowds out native vegetation, reduces recreational opportunities, and ultimately can harm fish and bird species. The plant can also clog intakes where rivers and reservoirs are used for drinking water supplies and irrigation.

In fall of 2013, members of the task force conducted a survey that found Hydrilla present in 25 miles of the Eno River. The most infested area was a 15-mile section from the N.C. Highway 70 bridge east of Hillsborough to Guess Road in Durham. Task force members continue to survey the upper portions of the Eno River watershed and add sites to the management plan as needed.

Mark Fowlkes, piedmont aquatic habitat coordinator with the N.C. Wildlife Resources Commission’s Division of Inland Fisheries, is optimistic about the future of the management effort. “The two-year pilot project showed Hydrilla could be successfully treated in a riverine system,” he said. “Moving forward, the task force will continue monitoring the treated area and survey the upper watershed for potential sources, which will include working with private pond owners.”

The Eno River Hydrilla Management Task Force is a group of local, state and federal government representatives including the N.C. Wildlife Resources Commission, N.C. Division of Water Resources, N.C. State Parks, Orange and Durham counties, the town of Hillsborough, and the cities of Durham and Raleigh.  It has collaborated since 2007 to evaluate and address the Hydrilla threat in the Eno River. For more information on the pilot project, visit or contact Mark Fowlkes or 336-527-1547. 


About the North Carolina Department of Natural and Cultural Resources

The N.C. Department of Natural and Cultural Resources (NCDNCR) is the state agency with a vision to be the leader in using the state's natural and cultural resources to build the social, cultural, educational and economic future of North Carolina. NCDNCR's mission is to improve the quality of life in our state by creating opportunities to experience excellence in the arts, history, libraries and nature in North Carolina by stimulating learning, inspiring creativity, preserving the state's history, conserving the state's natural heritage, encouraging recreation and cultural tourism, and promoting economic development.

NCDNCR includes 27 historic sites, seven history museums, two art museums, two science museums, three aquariums and Jennette's Pier, 39 state parks and recreation areas, the N.C. Zoo, the nation's first state-supported Symphony Orchestra, the State Library, the State Archives, the N.C. Arts Council, State Preservation Office and the Office of State Archaeology, along with the Division of Land and Water Stewardship. For more information, please call (919) 807-7300 or visit



N.C. Department of Natural and Cultural Resources 

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