Provincial Containment Strategy Butomus umbellatus (Flowering Rush)

Transcription

1 Provincial Containment Strategy Butomus umbellatus (Flowering Rush) Prepared by: B.C. Ministry of Forests, Lands and Natural Resource Operations June 2015

2 Acknowledgements The Ministry of Forests, Lands and Natural Resource Operations would like to acknowledge the following individuals and organizations for their valuable contributions to this project: Anna and Martin Eastman, Baker Creek Enhancement Society, Bruce Edwards, Cariboo Regional District, Fraser Valley Invasive Plant Council, K.C. Log Booming, and private landowners who provided access to survey sites. The original draft was completed by Crystal Klym, P.Ag. (June 2015). Page i

3 Table of Contents Acknowledgements... i Background... 1 Extent... 1 Hatzic Lake Survey Results... 1 Bouchie Lake Survey Results... 2 Stakeholder Consultation and Extension... 2 Implementation Recommendations... 3 Physical Containment... 3 Public Education and Outreach... 4 Targeted Surveys... 4 Exploring Treatment Options... 5 Issues, Challenges and Opportunities... 5 Conclusion... 6 Appendix I: Flowering Rush Provincial Extent Map... 7 Appendix II: Flowering Rush Presence/Absence Survey Maps... 8 Appendix III: Proposed Physical Barrier Locations Appendix IV: Company Contact Information (Physical Barriers) Page ii

4 Background Butomus umbellatus is known to occur in British Columbia (BC) in two locations, the first in Hatzic Lake near Mission and the second in Bouchie Lake near Quesnel. Both waterbodies drain into the Fraser River. These sites were confirmed in 2014 through the design and implementation of Flowering Rush Extent Survey Plans that were developed by the Ministry of Forests, Lands and Natural Resource Operations (FLNR). Results of these surveys contributed to the development of the BC Flowering Rush Containment Strategy, which proposes activities to contain current B. umbellatus infestations and prevent spread to neighbouring water-bodies. B. umbellatus is grown as an ornamental plant. Since the main pathway of introduction is horticulture, this is likely how B. umbellatus was introduced to both Bouchie Lake and Hatzic Lake. Once introduced to a water-body, B. umbellatus seeds, root fragments and bulbils can be easily dispersed by wind and water currents to downstream locations. B. umbellatus may be more widespread in BC than currently known. When not in flower it can be easily overlooked or confused with Sparganium spp. (bur-reed), native sedges (Cyperaceae spp.), bulrushes, and true rushes (Juncaceae spp.). Extent B. umbellatus presence has been confirmed at both Hatzic Lake and Bouchie Lake through presence/absence surveys that were completed as per Flowering Rush Extent Survey Plans that were developed for both water-bodies and in accordance with the BC Invasive Aquatic Plant Survey and Sample Collection Protocol. Surveys were led by the FLNR Invasive Plant Program. Presence/absence maps for surveys completed in 2014 are provided in Appendix II. Hatzic Lake Survey Results Hatzic Lake surveys were completed August and September Sample points were taken at key points along the Hatzic Lake littoral zone and mid-lake as well as Lower Hatzic Slough, and portions of Upper Hatzic Slough and Chilqua Slough. Where flowering rush infestations were extensive, protocol was modified to record presence start and end points. Additional surveys were completed by boat along the north and south shores of the Fraser River (from the mouth of Lower Hatzic Slough westward for approximately 2km), as well as shoreline surveys at high use access points (public boat launches) at Stave Lake, Cultus Lake and Hayward Lake. A survey was not completed at Ruskin Dam Recreation Site as it was closed to the public due to construction. The Fraser River was surveyed at high tide to permit boat access in the shallows. Poor visibility (0m) prevented observation of submerged plant material suspended in the water column or rooted to the substrate. Both emergent and submergent B. umbellatus were found to be extensive throughout Hatzic Lake and the Lower Hatzic Slough, excluding depths greater than 2.3 m. Both growth forms were found at the mouth of Chilqua Slough with submergent B. umbellatus continuing approximately 1.1 km up the slough. A continuous infestation of Page 1

5 both submergent and emergent B. umbellatus was observed about 0.7 km along Upper Hatzic Slough (from the mouth of Hatzic Lake to Farms Road crossing), and sporadic infestations of submergent B. umbellatus were recorded from Farms Road crossing northward approximately 0.8 km. Extent survey results indicate that B. umbellatus has not yet been introduced to the Fraser River. However, the risk of introduction remains high due to the extensive infestation in Lower Hatzic Slough (see Implementation Recommendations). Based on survey results, the pump station 1 may be providing an obstacle to spread from Lower Hatzic Slough to the Fraser River. B. umbellatus was not observed to occur at Cultus Lake, Stave Lake or Hayward Lake. The risk of introduction of B. umbellatus and other invasive aquatic species to these lakes is high due to their close proximity to Hatzic Lake and extensive recreational use. Therefore, shoreline and boat surveys are recommended for these water-bodies in 2015 (see Implementation Recommendations). Harvester and floatplane activity was confirmed on Hatzic Lake. The harvester is hired by private residents and operates solely on Hatzic Lake. Floatplane activity requires further investigation (see Implementation Recommendations). Bouchie Lake Survey Results Bouchie Lake surveys were completed August 14, 15, 19, and 20. Sample points were taken along the Bouchie Lake littoral zone and mid-lake as well as Bouchie Creek (inflow and outflow), Purser Creek (inflow), and Milburn Lake (high risk sites). B. umbellatus was found to be concentrated along the southern and western shoreline of Bouchie Lake, including the Purser Creek inflow, with sporadic occurrences along the northern and eastern shoreline. B. umbellatus was not observed at either the Bouchie Creek inflow or outflow nor was it found to occur at mid-lake sample points, where water depths are greater than 3m. Surveys completed at Milburn Lake high-risk sites (public boat launches, public fishing/recreation access points, and private water frontages) found B. umbellatus to be absent at this time. Based on survey results, it appears that B. umbellatus is restricted to Bouchie Lake and has not yet spread to adjacent water-bodies. However, floatplane activity in the lake will require expansion of the targeted search area in future (see Implementation Recommendations). Due to the absence of B. umbellatus in the Bouchie Creek outflow, as well as the issue of inaccessibility and safety, surveys were not conducted along the Fraser River. Stakeholder Consultation and Extension B.umbellatus information bulletins were laminated and posted at high use areas around the communities of Mission and Hatzic Lake. In addition, flowering rush alerts and bulletins were provided to key stakeholders in Hatzic Lake and Bouchie Lake for local distribution. A public information session was held at the Hatzic Prairie Hall on November 26, and a public information package and questionnaire was circulated to Bouchie Lake residents in April In 2014, pump station water height was recorded at 2.5m in August and 0.68m in September. Page 2

6 The purpose of these consultation activities was to provide information on the biology, impacts and status of B.umbellatus; present 2014 extent survey findings; provide overview of the proposed provincial containment program; and gather stakeholder and public input, which helped identify priority actions for program implementation (see Implementation Recommendations). Stakeholders and the public were also invited to become involved in the containment program by various means, such as educating others, providing waterfront access for future surveys, reporting new sites, and maintaining and monitoring containment barriers. The different consultation approaches were based on advice from local stakeholders and considered to be the most effective way of engaging with the public in each region. However, based on feedback received from questionnaire respondents, a public information session will be held by FLNR in Bouchie Lake to support the public engagement to date. Implementation Recommendations Due to the extent of B. umbellatus in both Hatzic Lake and Bouchie Lake, in combination with the extreme mobility of plant propagules in water and the absence of effective eradication methods, physical containment of existing infestations is recommended as an immediate action in Additional recommended activities include delivering a targeted education and outreach program, expanding presence/absence surveys, and exploring new, effective treatment options as they become available. Physical Containment Based on 2014 survey results, containment boundaries were delineated around Hatzic Lake and Bouchie Lake (Appendix II) to identify priority locations for physical containment efforts. Installation of barrier curtain or floating debris boom technologies at inflows and outflows may be effective in preventing the non-human dispersal of B. umbellatus propagules (rhizomes, bulbils, and seeds) to uninfested inflows, outflows, and adjacent water-bodies, such as the Fraser River. To determine appropriate materials, supplies, and costs the following information is required for each installation point: Maximum and minimum water depth 2 Frequency of water fluctuation Water velocity as well as wind, wave and ice action Running width and depth Estimated debris volume and frequency of maintenance Bottom sediment/material (anchoring unit) Freshwater vs. salt water 2 Furling lines, which can be manually raised or lowered to accommodate fluctuating water levels, can be added to barrier curtains. Page 3

7 Development of detailed site plans for the proposed physical barrier installation locations (Appendix III), permitting and associated maintenance and monitoring plans are also recommended. Public Education and Outreach Human-assisted introductions, both intentional (plantings, improper disposal of garden waste) and unintentional (plant parts hitchhiking on boats or equipment) pose the biggest threat to the spread of B.umbellatus. Therefore, the goals of public education and outreach are to increase new reports of flowering rush (outside of impacted waterbodies); promote the sale, purchase, trading and planting of non-invasive alternatives; and encourage boaters and others to Clean-Drain-Dry boats, equipment and gear. These goals can be achieved through the public learning how to identify and report B.umbellatus; identification of high risk access points; design and installation of informational signage at priority access points; selection of non-invasive alternatives for yard and garden projects; and adoption of the provincial Clean-Drain-Dry program. Target audiences include full time and part time residents, adjacent agriculturists, anglers, boaters, local government, floatplane and harvester operators, stewardship groups, garden clubs, nurseries and garden centers. A public information session would be beneficial in Bouchie Lake to support the stakeholder engagement already completed in that area. Periodic communications to local stakeholders and residents on the containment program and flowering rush status will further increase awareness and information sharing. Local support and stewardship will be key to the success of containing flowering rush to impacted water-bodies in BC. Targeted Surveys Targeted presence/absence surveys are recommended for high-risk sites including adjacent upstream/downstream water-bodies, water-bodies in the vicinity of known infestations that share potential pathways of introduction (fishing, boating, milfoil harvesting, floatplanes, etc) and BC water-bodies adjacent to infested areas bordering the province (e.g. Pend Oreille, WA). Based on 2014 extent survey results, high-risk water-bodies in the Fraser Valley include, but are not limited to, Nicoman Slough, Stave Lake, Cultus Lake, Hayward Lake, Ruskin Dam, and the Fraser River. High-risk waterbodies in the Cariboo include, but are not limited to, Dragon Lake and Ten Mile Lake. Additional high-risk water-bodies will be identified through subsequent targeted surveys as well as further stakeholder and public consultation. Annual monitoring is recommended for Hatzic Lake and Bouchie Lake inflows and outflows, both upstream and downstream of installed barriers, and the Fraser River downstream of Hatzic Lake, to ensure B. umbellatus is not dispersing. Visibility in the lower Fraser River is extremely poor due to high sediment and turbidity. If possible, the Fraser River should be surveyed at low tide to increase visibility in the water column and along river margins. In addition, the Canadian portion of the Pend D Oreille River should be surveyed by boat due to Page 4

8 confirmed upstream infestations of B.umbellatus in Washington and Idaho. Although B.umbellatus has not been recorded in the Canadian portion of the Pend D Oreille to date, infestations are reported to be spreading northward (upstream) from the U.S. at an alarming rate. Exploring Treatment Options Established treatment options for B. umbellatus in North America are ineffective in achieving eradication. However, there are some approaches that may be effective in suppressing growth under specific circumstances including biological, chemical and mechanical controls. An international consortium that includes representation from FLNR is contributing towards research to develop biological control agents for B. umbellatus. Biological control is intended to regulate target invasive plant populations, not contain or eradicate them. B. umbellatus biological control availability in BC is anticipated in 5 to 10 years, thus not an immediate treatment option for existing infestations. In the US, several states have trialed the use of numerous products for the chemical control of B. umbellatus with poor efficacy. Anecdotal evidence suggests high control efficacy may be obtained for B. umbellatus using the herbicide active ingredient diquat. In 2015, B. umbellatus diquat trials will be undertaken in Idaho and Alberta to verify the efficacy of this treatment option. FLNR will be following the delivery and outcomes of these trials closely. Mechanical control is only effective in the removal of extremely small infestations (i.e., 1-2m 2 ) thus not a viable treatment option on a landscape scale for extensive infestations like those present in Hatzic Lake and Bouchie Lake. In fact, the disturbance caused by mechanical control of B. umbellatus can result in increased flowering rush distribution and density, given the reproductive biology of this species. Issues, Challenges and Opportunities One of the biggest challenges associated with containing B. umbellatus to its current extent is the human-assisted unintentional spread to currently uninfested water-bodies via contaminated boats, boat trailers, harvesters, gear, equipment, and floatplanes. Intentional introduction of B. umbellatus to new areas as an ornamental species is also of concern. This can, however, provide an opportunity to raise awareness around aquatic invasive species and garner community support to prevent their spread. In addition, increased public knowledge on how to identify and report B. umbellatus infestations will assist in determining if this species is spreading beyond established containment boundaries. Revisions to the BC Weed Control Regulation that create the authority to restrict the sale and transport of flowering rush will be a significant factor in preventing new introductions and spread in BC. Vectors of spread, such as floatplanes and milfoil harvesters, can provide additional challenges in determining where to target future extent surveys and monitoring programs. Better understanding of how these vectors can contribute to local and long- Page 5

9 distance dispersal will assist FLNR and other stakeholders in preventing new incursions of B. umbellatus and other aquatic invasive species. Monitoring the efficacy of physical containment barriers, such as barrier curtains and floating debris booms, will provide valuable information on their feasibility as a containment option and could be adopted to contain other aquatic invasive plant infestations around the province. However, the costs associated with these technologies may be prohibitive to some groups or not an available option for larger water-bodies. Conclusion Eradication of B. umbellatus in both Hatzic Lake and Bouchie Lake is highly unlikely. Dramatic water fluctuations in Hatzic Lake will create further management challenges by favouring B.umbellatus growth and inhibiting the natural regeneration of desirable species. Management of isolated occurrences of B. umbellatus within Hatizic Lake and Bouchie Lake is unlikely given its high reproductive success, various modes of dispersal, limited effective control options, and significant recreational use in both water-bodies. Therefore, containing existing infestations by restricting upstream and downstream dispersal and preventing new introductions to nearby water-bodies are of utmost importance. Page 6

10 Appendix I: Flowering Rush Provincial Extent Map Page 7

11 Appendix II: Flowering Rush Presence/Absence Survey Maps Flowering rush absent Flowering rush present (point) Flowering rush present (extent of infestation) Flowering rush present (extent of infestation) Proposed containment line Page 8

12 Flowering rush absent Flowering rush present (point) Flowering rush present (extent of infestation) Flowering rush present (extent of infestation) Proposed containment line Page 9

13 Bouchie Lake Milburn Lake Bouchie Creek Flowering rush absent Flowering rush present (point) Flowering rush present (extent of infestation) Flowering rush present (extent of infestation) Proposed containment line Page 10

14 Flowering rush absent Flowering rush present (point) Flowering rush present (extent of infestation) Flowering rush present (extent of infestation) Proposed containment line Page 11

15 Appendix III: Proposed Physical Barrier Locations Proposed Priority Installation Points Upper Hatzic Slough Chilqua Slough Lower Hatzic Slough (downstream from pump station) Lower Hatzic Slough (upstream from pump station) Bouchie Creek Inflow Purser Creek Inflow Bouchie Creek Outflow Location Details Hatzic Lake Hatzic Prairie, where the slough crosses Dale Road (south side of road), just west of Farms Road UTM: 10U E N Dewdney, where the slough crosses the private driveway (west side of driveway), accessed from Hawkins Pickle Road UTM: 10U E N West side of Dyke Road, outflow of Lower Hatzic approximately 100m west of the dyke UTM: 10U E N West side of Dyke Road, outflow of Lower Hatzic approximately 100m west of the dyke UTM: 10U E N Bouchie Lake 100m upstream from the mouth of Bouchie Creek as it enters Bouchie Lake UTM: 10U E N 100m upstream from the mouth of Purser Creek as it enters Bouchie Lake UTM: 10U E N 100m downstream from the mouth of Bouchie Creek as it leaves Bouchie Lake UTM: 10U E N Timing of Installation Spring 2015 Spring 2015 Spring 2015 Spring 2015 Spring 2015 Spring 2015 Spring 2015 Page 12

16 Appendix IV: Company Contact Information (Physical Barriers) The following companies were contacted in December Representatives listed below confirmed their availability and interest in working with FLNR on physical barrier cost estimates and installation: Elastec/American Marine Duane Bennish, Division Manager Phone: +1 (618) Web: Comments: ISO 9001:2008 Certified. Provided excellent guidance via . Granite Environmental Inc. John Papczynski, Division Manager Phone: +1 (888) Web: Comments: Provided excellent guidance over the phone and via . Variety of options available. Aquatechnex Terry McNabb, Aquatic Biologist/Certified Lake Manager Phone: +1 (855) Web: Comments: Aquatechnex has worked for the Regional District Kootenay Boundary (Christina Lake). They have used containment systems to keep herbicides in contact with target vegetation in high water exchange environments (Pend D Orielle and Spokane River systems). Costs depend entirely on water depth. Page 13