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HomeMy WebLinkAboutAgenda - 06-19-2012 - 8aORANGE COUNTY BOARD OF COMMISSIONERS ACTION AGENDA ITEM ABSTRACT Meeting Date: June 19, 2012 SUBJECT: Hydrilla in the Eno River DEPARTMENT: Environment, Agriculture, Parks and Recreation ( DEAPR) ATTACHMENTS: 1. Hydrilla Memorandum 2. Hydrilla Identification (NRCS) 3. Hydrilla Information Sheet Action Agenda Item No. PUBLIC HEARING: (Y /N) INFORMATION CONTACTS: David Stancil, 245 -2510 Thomas Davis, 245 -2513 No PURPOSE: To update the Board concerning the extent of Hydrilla, an invasive aquatic plant, in the Eno River. BACKGROUND: Hydrilla ( Hydrilla verticcilata) is an invasive aquatic plant, originally found in Asia, that was first noted in the United States in the 1960s. Since that time, hydrilla has spread rapidly and has reached nuisance levels in many locations. Some individuals call hydrilla "the perfect aquatic plant" since it spreads rapidly, is able to reproduce in four different ways, grows in extremely low light, and is able to crowd out native aquatic vegetation. Staff has learned that hydrilla is likely present throughout the Eno River in Orange County. Eno River State Park staff indicated that hydrilla is the "number one resource management problem in the Eno: more so than water flow." Hydrilla causes negative water quality impacts, can be harmful to the river ecosystem, and adversely impacts the recreational experiences of people during the summer months, as explained in the attached memo. Hydrilla can be spread from one water body to another via watercraft or waterfowl that move from one water body to another. Finally, the plant has also been spread by people that discard materials from their home aquariums. Aquatic herbicides and sterile grass carp have been used with some success to manage hydrilla in lakes and reservoirs — including Lake Orange and West Fork of the Eno Reservoir — although grass carp can also remove native aquatic vegetation in addition to invasive species. Neither herbicides nor grass carp have been used successfully to control hydrilla in a riverine setting. Management of hydrilla in a flowing (lotic) system is very difficult. Further research is being conducted by the Department of Crop Science at North Carolina State University. Given the potentially harmful impacts of hydrilla infestation and the ease with which this invasive plant spreads, public outreach and education should be considered important components of any future efforts to manage the proliferation of this plant species. DEAPR staff will continue to monitor the situation, help with increasing public awareness of hydrilla, offer other technical 2 assistance to the County's partners as needed, and report back to the Board at some future date. FINANCIAL IMPACT: There is no financial impact at this time although management of hydrilla in the Eno River, and possibly elsewhere in Orange County, could ultimately require some financial commitment on the part of the County. RECOMMENDATION(S): The Manager recommends that the Board consider and discuss the information presented. 3 Department of Environment, Agriculture, Darks & Recreation MEMORANDUM TO: Frank Clifton, County Manager Michael Talbert, Assistant County Manager Dave Stancil, DEAPR Director FROM: Tom Davis, Water Resources Coordinator DATE: May 7, 2012 RE: Emerging Water Resource Issue: Hydrilla in the Eno River Recently I attended a meeting concerning the status of Hydrilla verticcilata in the Eno River. Hydrilla is a fast - growing, perennial, invasive non - native aquatic plant that was reportedly originally brought into the US in the 1950s as an aquarium plant. Since that time, this plant has spread rapidly in the southeastern US and is now on the US Federal Noxious Weed List and is listed as a Class A noxious weed in North Carolina, meaning it is illegal to import, culture, transport or sell it in the state. According to some experts, hydrilla is the #1 aquatic weed in the US. Hydrilla is a highly adaptable plant that can grow in extremely low light and can reproduce through any of four different methods; via fragmentation, tubers, turions (dormant buds) or seeds. This adaptability has led some to call hydrilla "the perfect aquatic plant ". In addition, waterfowl, boats and humans are also likely responsible for aiding the spread of this plant. Two publications providing more details concerning hydrilla are attached. Hydrilla in the Eno River Typically, hydrilla is present in lakes. It has been found in the recent past in the West Fork of the Eno River Reservoir as well as in Lake Orange. However, according to researchers from NC State University, NCDENR Division of Water Resources (DWR) personnel, and the staff of the Eno River State Park (ERSP), hydrilla is also present throughout the upper Eno River to a point at least 1.2 miles east (downstream) of US 15 -501 in Durham County. It is likely that hydrilla is now present throughout the Eno River in Orange County. The extent of hydrilla in Orange County Department of Environment, Agriculture, Parks & Recreation PO Box 8181, Hillsborough, NC 27278 Phone: (919) 245 -2510 Fax: (919) 644 -3351 4 tributaries of the Eno River is not known, although it has been reported to be present in Sevenmile Creek. It was the consensus of the meeting attendees that the presence of hydrilla in a flowing water (lotic) system is fairly unique. Hydrilla Impacts Given the propensity for this invasive plant to dominate native aquatic plants to the point that these other plants are effectively eliminated, it is safe to say that hydrilla has infested the upper Eno River and is likely to continue to spread. Some meeting attendees think that hydrilla has surpassed the nuisance level in the Eno and now represents a serious threat the ecosystem of the river. Hydrilla infestation is problematic for several reasons: a) public perception, b) water quality impacts, and c) ecosystem impacts. According to the Superintendent of the ERSP, Keith Nealson, "Hydrilla is the number one resource management problem in the Eno; more so than water flow." He reported that during the summer, when hydrilla is widely abundant in the river, he receives many questions and complaints about the presence of the plant. Hydrilla is very unsightly in the river since it spreads widely and is highly visible. The plant also interferes with fishing such that the Eno is virtually "unfishable" from July to October. In general, hydrilla has a very negative impact on the recreational experience of visitors to the state park. Water quality in the Eno can be negatively impacted by the presence of hydrilla. During the summer months, when hydrilla is abundant in the river, the concentration of dissolved oxygen (DO) in the river can be reduced. The naturally occurring DO cycle can also be impacted on a daily and seasonal basis, as much lower DO concentrations than normal can occur at night during the summer months, and when hydrilla plants die in the late summer months, the decomposition of the plants consumes a great deal of DO. These processes negatively impact water quality and can cause fish kills in the river. Hydrilla can also cause ecosystem impacts. The Roanoke Bass (ambloplites cavifrons) is naturally found in only the Tar and Neuse River basins in North Carolina. The extent of these sunfish has been greatly reduced such that it is now listed as Significantly Rare by the NC Natural Heritage Program. NC Wildlife Resources Commission staff report that hydrilla in the Eno seems to be reducing the number of larger sized Roanoke Bass in the river. The longer term impact of hydrilla on the Roanoke Bass in the Eno is not currently known, nor whether or not hydrilla is impacting any other significant or endangered species that exist in the Eno River. In addition, a relatively new disease has been linked to hydrilla. Avian vacuolar myelinopathy (AVM) is a disease that has been found to affect the brain tissue of waterfowl in the southeastern US. Plant- eating waterfowl, including Canada geese and mallard ducks, become sick with AVM and die as a result of ingesting Orange County Department of Environment, Agriculture, Parks & Recreation PO Box 8181, Hillsborough, NC 27278 Phone: (919) 245 -2510 Fax: (919) 644 -3351 5 cyanobacteria that is naturally present on invasive aquatic vegetation, including hydrilla. Predatory birds, including bald eagles and American coots, can be infected by AVM after consuming impacted waterfowl. Hundreds of bald eagles and thousands of other waterfowl have reportedly been killed by AVM since this disease was first discovered approximately ten years ago. At least one case of AVM has been confirmed in the Raleigh area. Hydrilla Control Efforts to control hydrilla in lakes typically include the use of sterile triploid grass carp or the application of aquatic herbicides. Manual removal of hydrilla is not effective. Four objectives for management of hydrilla were discussed at the meeting and in subsequent communications: 1. Reduce hydrilla infestation level. 2. Protect habitat in the ecosystem such that stable, sustainable populations of native aquatic plants are maintained. 3. Protect river fauna so that populations are maintained, especially for rare species. 4. Maintain a "natural' river system that retains its aesthetic and recreational value. A list of possible next steps emerged from the recent efforts. This list includes: 1. Experimental treatment of hydrilla in a small area of the Eno with endothall, an EPA registered aquatic herbicide. The lowest effective concentration and required contact time would be used. 2. Inventory native submerged aquatic vegetation in the Eno and conduct off -site research of sensitivity of these plant species to endothall and other aquatic herbicides. 3. Conduct low -level toxicity studies of invertebrate species present in the Eno to assess the risk of low -dose herbicide exposure. 4. Conduct an experimental release of triploid grass carp to determine behavior and effectiveness of these fish. 5. Investigate other possible management options and explore funding options. 6. Conduct outreach efforts to educate members of the public. Elimination of hydrilla from the Eno River does not appear to be a simple process. There are apparently few instances of hydrilla being present in a flowing aquatic (lotic) system such as the Eno. The NCDENR Division of Water Resources (DWR) includes an Aquatic Weed Control Program that can provide technical assistance to property owners who may be having problems with invasive aquatic plants. Cost share programs are available to local governments, public utilities and Soil and Water Conservation Districts for hydrilla assessment and management efforts. Urange County Department of Environment, Agriculture, Parks & Recreation PO Box 8181, Hillsborough, NC 27278 Phone: (919) 245 -2510 Fax: (919) 644 -3351 According to the 2012 DWR Aquatic Weed Control work plan for 2012 that is available online, DWR is planning to assist the Town of Hillsborough with the purchase and placement of 600 triploid grass carp in the West Fork Eno Reservoir, in addition to a limited herbicide application in the reservoir. DWR is also scheduled to assist the ERSP with monitoring of the hydrilla situation as well as a possible application of herbicide. DWR is also planning to assist the Orange Alamance Water System with the assessment and potential treatment of hydrilla, and possibly parrot feather, another invasive aquatic plant, in Corporation Lake. Recommendations DEAPR recommends that Orange County staff continue to monitor the situation, help with increasing public awareness of hydrilla, offer other technical assistance to our partners as needed, assist with research and management efforts where feasible, and report back to the Board at some future date. Increasing public awareness of the hydrilla infestation of the Eno River appears to be a logical, low - cost next step to pursue at this time. Future participation in management efforts to control the hydrilla infestation of the Eno should be encouraged and facilitated where possible. Attachments cc: Orange County Commission for the Environment Rich Shaw, DEAPR Land Conservation Manager Dan Derby, Parks Superintendent Kevin Lindley, Staff Engineer urange county Department of Environment, Agriculture, Parks & Recreation PO Box 8181, Hillsborough, NC 27278 Phone: (919) 245 -2510 Fax: (919) 644 -3351 7 NR C S U.S. Department of Agriculture Natural Resources Conservation Service 344 Merrow Road,Suite A * Tolland, Connecticut 06084-3917 * (860)871-4011 * www.ct.nres.usda.gov . . Hydrilla Hydrilla verticillata (L.f.) Royle Alternate Latin Names: Elodea verticillata(L.f.)F.Muell.;Serpicula verticillata L.£;Hydrilla lithuanica(Andrz. ex Besser)Dandy Alternate Common Name: Indian Star-vine;Waterthyme -perennial(occasionally annual)water plant with leaves whorled on underwater stems -middle and upper stem whorls have mostly 5 to 8 leaves(occasionally 3 - 12 leaves per whorl) -leaf edges are finely toothed; teeth visible to the naked eye(look closely!) -leaves less than 1" long(1/4"to a little over 3/4" long); narrow(about 1/8"wide) -has both subterranean turions("tubers")and stem turions(described below) -plants may be rooted(in as much as 30 feet of water)or may be floating fragments -flowers tiny,floating;petals translucent, less than 1/4" long; male flowers detach from plant With its narrow,whorled, leaves,Hydrilla may be confused with native Water-weeds (Elodea Michx.). Native Water-weeds typically have 3 leaves per whorl while Hydrilla typically has 5-8 leaves per whorl in its middle and upper stem. In contrast to Hydrilla's toothed leaves,the teeth on the native Water-weed leaf margins are not visible to the naked eye. Subterranean turions (also called"tubers")grow in the soil beneath the water at the tips of"roots"(underground rhizomes or rooted stolons spreading over the sand or mud). The "tubers"are less than 1/2" long and resemble miniature, whitish to brown-black Jerusalem artichokes; and remain viable underground for many years. Stem turions are 1/4" long,tough, green, deciduous,bud-like shoots found along the stem. Stem turions remain viable less than a year. The native Water-weeds have dark green, leafy turions at the stem tips, but no underground "tubers". photo by -_ r Dave Spencer, photo by Dave Spence USDA-ARS f ' 4J ry k r e' �s Text and photos by: Charlotte Pyle,October 2002 Helpful review provided by:Lillian Willis The U S Department of Agriculture(USDA)prohibits discrimination in all its programs and activities on the basis of race,color,national origin,sex,religion,age,disability,political beliefs,sexual orientation,or marital or family status(Not all prohibited bases apply to all programs)Persons with disabilities who require alternative means for communication of program information(Braille,large print,audiotape,etc)should contact USDA's TARGET Center at 202-720-2600(voice and TDD) To file a complaint of discrimination,write USDA,Director,Office of Civil Rights,Room 326-W,Whitten Building,1400 Independence Avenue,SW, Washington,DC 20250-9410 or call(202)720-5964(voice and TDD) USDA is an equal opportunity provider and employer. 11/2002 (waterthyme) Hydrilla verticillato (L.f.) Royle Invasive Federal Noxious Weed Noxious in 17 states A submersed, rooted, perennial aquatic plant with a very fast growth ,.. rate. The stems grow quickly to the surface of the water and spread lat- erally. Hydrilla is one of ._ the most invasive plants infesting waterways in TM the Carolinas. There are two biotypes: monoe- M cious and dioecious. The dioecious biotype is more robust. .t Leaves: Oblong, sessile, i. and whorled in groups of 4 to 8 around the stem. � � Leaf margins are serrated, and color can range from light to dark green and even reddish depending upon the environment. i 9 Flowers: Small, delicate, and inconspicuous. They appear fleet- ingly just at the surface of the wa- ter in late summer and early fall. Reproduction: One reason that hydrilla is so invasive is because it can reproduce by fragmentation as well as from stolons, tubers ill' (pictured right), and turions. Turi- ons are produced in the leaf axils, while tubers (about the size of a pea) are produced at the ends of the rhizomes. Habitat: An intro- 9 � duced noxious plant that has become established in freshwa- ter areas throughout much of the south- eastern U.S. Similar Species: Hydrilla is similar in appearance to Egeria, but hydrilla has ser- f �y�r�lla rations along the leaf ! lydrilla vertcijlata margin, forms underground tubers, and feels coarse to the touch. Egeria has very small serrations along the leaf, requiring a hand lens to see them, and feels soft and smooth when drawn through the hand. Submersed 1 f �I na► River H s Emerging-, ater ; F S �"- +.R Hydrilla in Eno River,Pleasant Green Access Area,Aug 2011,courtesy E.Nygard Eno River Hydrilla Hydrilla - The Perfect Aquatic Plant? i • Highly adaptable Grows in nearly all levels of light • Overwhelms native vegetation ti • Four methods of reproduction- Via fragment, tuber, stolon, turion Hydrilla in INC coastal waters Courtesy Rob Emens,DWR. Eno River H drib ��" y Problems: Aesthetics � . -Water Quality fmpacts � �, � Potentially to cyanobacterial colonies on Ecosystem Impacts hydrilla and other aquatic plants Aquatic plants and epiphytic algae are . Roanoke Bass primary food source for coots rfowl are by Bald Eagles Nuisance! Fishing impacts .-= CounesyUniversityofGeorgla. _- , "`" - Wamell School of Forestry and Natural Resources Eno River Hydrilla Management options? . Herbicide Endo#hall — used in lake infes#a#ions Effectiveness in flowing (fotic) system?? Need to study impact to native aquatic vegetation Triploid grass carp — used in lakes and reservoirs Effectiveness in flowing (lotic) systems?? Can also eliminate native vegetation - . Maybe ok in reservoirs, but not in the Eno Takes some time to be effective in lakes and then only effective for a few years — until fish mature. • Public outreach and educa#ion 12 Y • ` � ta:�`vater kr�si urceS' „ �T E� d Control Qfog, rn . F