Tahoe Divers Tahoe Divers ConservancyConservancy

Lake Tahoe Lake Tahoe Aquatic Invasive Aquatic Invasive

Weeds ReportWeeds Report

Invasive Aquatic Weed Invasive Aquatic Weed Survey and Removal ProjectSurvey and Removal Project

• Most boaters and recreationists have by now heard of Most boaters and recreationists have by now heard of Eurasian Eurasian watermilfoilwatermilfoil, an aggressive and invasive aquatic weed that is , an aggressive and invasive aquatic weed that is spreading around Lake Tahoe’s shoreline and now into the Truckee spreading around Lake Tahoe’s shoreline and now into the Truckee River. River.

• This invasive weed grows very quickly, forming dense mats of This invasive weed grows very quickly, forming dense mats of vegetation that restrict boating, swimming, fishing, and water skiing. vegetation that restrict boating, swimming, fishing, and water skiing. It also competes aggressively with native aquatic plants and degrades It also competes aggressively with native aquatic plants and degrades water quality and aquatic habitats.water quality and aquatic habitats.

• To compound the problem, this aquatic weed is difficult to control. To compound the problem, this aquatic weed is difficult to control. While there are a variety of methods available, including mechanical While there are a variety of methods available, including mechanical harvesting, insect bio-controls, drying and/or freezing the water body, harvesting, insect bio-controls, drying and/or freezing the water body, and chemical control, no single method will do the job in Lake Tahoe. and chemical control, no single method will do the job in Lake Tahoe. Mechanical harvesting, most commonly used by local marinas, Mechanical harvesting, most commonly used by local marinas, actually helps spread the weed by releasing plant fragments that float actually helps spread the weed by releasing plant fragments that float away and establish new populations in nearby marinas and beaches. away and establish new populations in nearby marinas and beaches.

• In an effort to remove Eurasian watermilfoil from Lake Tahoe and the In an effort to remove Eurasian watermilfoil from Lake Tahoe and the Truckee River watershed, the Truckee River watershed, the Tahoe Divers ConservancyTahoe Divers Conservancy will train will train divers to identify, survey, and hand-remove the aquatic weed. Hand–divers to identify, survey, and hand-remove the aquatic weed. Hand–removal is somewhat labor intensive, but is very effective at removing removal is somewhat labor intensive, but is very effective at removing the plant by the roots, reducing the spread by plant fragments, and the plant by the roots, reducing the spread by plant fragments, and minimizing disturbance to the lakebed. Project start date was set for minimizing disturbance to the lakebed. Project start date was set for Fall 2006.Fall 2006.

• Until 1994, no surveys for rooted Until 1994, no surveys for rooted aquatic macrophytes had been aquatic macrophytes had been conducted, particularly with a goal conducted, particularly with a goal of documenting the presence of of documenting the presence of non-native species. Early reports non-native species. Early reports (1975) of Watermilfoil species near (1975) of Watermilfoil species near Taylor Creek did not identify the Taylor Creek did not identify the species of Myriophyllum, nor were species of Myriophyllum, nor were vouchers or photographic records vouchers or photographic records made. made.

• However, severe impacts from However, severe impacts from aquatic plants were observed in the aquatic plants were observed in the Tahoe Keys by the end of the Tahoe Keys by the end of the 1970’s and early 1980’s, during 1970’s and early 1980’s, during which time mechanical harvesting which time mechanical harvesting was begun. The US Department of was begun. The US Department of Agriculture/ Agricultural Research Agriculture/ Agricultural Research Service conducted surveys Service conducted surveys periodically from 1995 to 2006 periodically from 1995 to 2006 (Anderson and Spencer 1995; (Anderson and Spencer 1995; Anderson and Spencer 1996; Anderson and Spencer 1996; Anderson 1997). The most recent Anderson 1997). The most recent USDA-ARS survey of the entire 72 USDA-ARS survey of the entire 72 mile lake shoreline was completed mile lake shoreline was completed in the fall, 2006. Specimen in the fall, 2006. Specimen vouchers were made and all vouchers were made and all locations are geo-referenced. locations are geo-referenced.

Near the Tahoe City DamNear the Tahoe City Dam

Area around outletArea around outlet

Taylor Creek MarshTaylor Creek Marsh

East Shore – Marla BayEast Shore – Marla Bay

2006-2007 Work 2006-2007 Work ProgramProgram• The Tahoe Divers Conservancy members recognize that invasive weed infestations occur The Tahoe Divers Conservancy members recognize that invasive weed infestations occur

within the Lake Tahoe basin that reduce the biological, recreational and economical value of within the Lake Tahoe basin that reduce the biological, recreational and economical value of the land and have a negative impact upon the environment by suppressing native plant the land and have a negative impact upon the environment by suppressing native plant species. A coordinated approach to identifying sites, developing responses and educating the species. A coordinated approach to identifying sites, developing responses and educating the public will result in a more effective effort to reduce or eliminate invasive weed infestations. public will result in a more effective effort to reduce or eliminate invasive weed infestations. Responses to invasive weed infestations may include mechanical, biological, chemical and/or Responses to invasive weed infestations may include mechanical, biological, chemical and/or cultural control methods that could minimize further invasive weed infestations in the Lake cultural control methods that could minimize further invasive weed infestations in the Lake Tahoe basin. Tahoe basin.

• Accomplishing the above goals will require the following:Accomplishing the above goals will require the following:• 1.1. EDUCATIONEDUCATION: Increase public and staff awareness of invasive weeds.: Increase public and staff awareness of invasive weeds.• 2.2. EXCLUSIONEXCLUSION: Exclude invasive weeds from the Lake Tahoe basin.: Exclude invasive weeds from the Lake Tahoe basin.• 3.3. PREVENTIONPREVENTION: Prevent the establishment of new invasive weed infestations and : Prevent the establishment of new invasive weed infestations and

spread of existing invasive weed infestations.spread of existing invasive weed infestations.• 4.4. CONTROLCONTROL: Promote the effective management or eradication of designated : Promote the effective management or eradication of designated

weeds.weeds.• 5.5. INFORMATION EXCHANGEINFORMATION EXCHANGE: Share technical information regarding control : Share technical information regarding control

methods, locations, new infestations, project success amongst parties and with other regional methods, locations, new infestations, project success amongst parties and with other regional and local weed management areas.and local weed management areas.

• 6.6. COOPERATIONCOOPERATION: Facilitate development of cooperative agreements for local : Facilitate development of cooperative agreements for local weed management areas which include opportunities for shared funding sources, resources, weed management areas which include opportunities for shared funding sources, resources, materials, personnel including volunteers, expertise, equipment, etc.materials, personnel including volunteers, expertise, equipment, etc.

DESCRIPTION OF DESCRIPTION OF METHODMETHOD

• Diver hand-pulled removal assisted by vacuum suction Diver hand-pulled removal assisted by vacuum suction removal involves an underwater diver pulling the plant out removal involves an underwater diver pulling the plant out by the roots, then ‘feeding’ it into a 3-6” intake suction by the roots, then ‘feeding’ it into a 3-6” intake suction hose that transfers the entire plant and associated water up hose that transfers the entire plant and associated water up to the water surface to a screen or collection box attached to the water surface to a screen or collection box attached to the side of the workboat. The dredge engine is usually a to the side of the workboat. The dredge engine is usually a 5 to 8 horsepower Honda or Briggs & Stratton. Sediment 5 to 8 horsepower Honda or Briggs & Stratton. Sediment type, visibility, and thoroughness in removal of the entire type, visibility, and thoroughness in removal of the entire plant, particularly the roots, affect the speed at which plant, particularly the roots, affect the speed at which plants are uprooted. The screen/basket separates the plants are uprooted. The screen/basket separates the pulled plant material from the associated water, which then pulled plant material from the associated water, which then passes back into the water column. The plant material is passes back into the water column. The plant material is retained on the screen and, after a threshold amount builds retained on the screen and, after a threshold amount builds up, is conveyed onto an approved on-shore dry disposal up, is conveyed onto an approved on-shore dry disposal area.area.

Underwater Visual Underwater Visual IdentificationIdentification

FLOW CHART AND RATING

Proximity of other milfoil infestations (within 50

miles)

Bottom is mud or silt

Draw down <10’

Plant life on the bottom?

Go through Lower Priority Rating

Process

No

No

No

No

Yes

Yes

Yes

Yes

Go to Top Priority Rating Process

Waterway is navigable, or used by boats, or has homes, or open to the

public

Work Program Specifics Work Program Specifics I. I. Site Preparation: Survey, Water Site Preparation: Survey, Water

Quality Measurement, Disposal Site Quality Measurement, Disposal Site SelectionSelection

• All divers shall ensure their equipment is thoroughly All divers shall ensure their equipment is thoroughly clean before entering the Lake, and that all equipment clean before entering the Lake, and that all equipment under their responsibility is cleaned after the end of the under their responsibility is cleaned after the end of the fieldwork before moving it from the project or Lake fieldwork before moving it from the project or Lake area.area.

• Before removing any EWM, divers will conduct an Before removing any EWM, divers will conduct an underwater survey of Emerald Bay to:underwater survey of Emerald Bay to:

• Determine the aerial extent, density and volume of Determine the aerial extent, density and volume of EWM targeted for removal, noting locations of EWM EWM targeted for removal, noting locations of EWM plants that are flowering or seeding;plants that are flowering or seeding;

• Identify other aquatic plants present and their locations;Identify other aquatic plants present and their locations;

Curlyleaf PondweedCurlyleaf Pondweed

• The Curlyleaf pondweed (The Curlyleaf pondweed (Potamogeton crispusPotamogeton crispus) is an aquatic plant ) is an aquatic plant with blue-green leaves that attach to spaghetti-like stems which with blue-green leaves that attach to spaghetti-like stems which produce small flowers that rise a few inches above the surface of the produce small flowers that rise a few inches above the surface of the waterwater. . Considered a deep water plant (up to 30 feet), it often Considered a deep water plant (up to 30 feet), it often colonizes in shallows. The plant can tolerate extreme low-light colonizes in shallows. The plant can tolerate extreme low-light conditions and cold water temperatures.conditions and cold water temperatures. It grows actively in winter It grows actively in winter months, reaches maximum density in late spring, and dies back in months, reaches maximum density in late spring, and dies back in mid-summer. It can reproduce by seed, but primary reproductive mid-summer. It can reproduce by seed, but primary reproductive means is through turionsmeans is through turions[i[i]], which are produced in late spring, and , which are produced in late spring, and by rhizomesby rhizomes[ii[ii]]. Turions remain dormant in the sediment through . Turions remain dormant in the sediment through summer until cooling water temperatures trigger germination in the summer until cooling water temperatures trigger germination in the fall.fall.

• [1][1] Turion- a swollen bud of many water plants that contains Turion- a swollen bud of many water plants that contains stored food. It becomes detached from the parent plant, enabling to stored food. It becomes detached from the parent plant, enabling to survive the winter.survive the winter.

• 2 Rhizome- a horizontal underground stem, with leaves and 2 Rhizome- a horizontal underground stem, with leaves and buds, that serves as a storage organ buds, that serves as a storage organ

Eurasian Watermilfoil Eurasian Watermilfoil (Myriophyllum(Myriophyllum spicatum spicatum))

• The Eurasian watermilfoil (The Eurasian watermilfoil (Myriophyllum spicatumMyriophyllum spicatum)) is an is an aquatic plant species that forms in ponds and lakes in both aquatic plant species that forms in ponds and lakes in both shallow and deep water environments up to about 30 feet. shallow and deep water environments up to about 30 feet.

• It requires stagnant to slow moving water to thrive but can also It requires stagnant to slow moving water to thrive but can also tolerate brackish water. The plant is rooted in bottom tolerate brackish water. The plant is rooted in bottom sediments and grows to the surface, usually 3-10 feet and up to sediments and grows to the surface, usually 3-10 feet and up to 30 feet. 30 feet.

• It forms dense mats of bright green, feathery leaves at the It forms dense mats of bright green, feathery leaves at the water surface which restrict light to the below water water surface which restrict light to the below water environment and restrict waterways. It thrives in areas that environment and restrict waterways. It thrives in areas that have been subjected to various natural and manmade have been subjected to various natural and manmade disturbances that have threatened native species and therefore disturbances that have threatened native species and therefore allow space for the plant to colonize. It does not spread rapidly allow space for the plant to colonize. It does not spread rapidly to areas where natives plants are well established. The plant to areas where natives plants are well established. The plant reproduces primarily by rhizomes and fragments.reproduces primarily by rhizomes and fragments.

Pathways of Plant Pathways of Plant IntroductionIntroduction

• The Eurasian watermilfoil (The Eurasian watermilfoil (Myriophyllum Myriophyllum spicatumspicatum) and Curlyleaf Pondweed ) and Curlyleaf Pondweed ((Potamogeton crispus)Potamogeton crispus) is likely introduced to is likely introduced to the Lake Tahoe Basin by boats, trailers, the Lake Tahoe Basin by boats, trailers, personal watercraft, contaminated personal watercraft, contaminated construction equipment and to a lesser extent construction equipment and to a lesser extent improper disposal of personal fish/plant improper disposal of personal fish/plant aquariums.aquariums.

• From: WORKPLAN SPECIFICATIONS FOR PROPOSALS TO CONDUCT A FEASIBILITY STUDY FOR VARIOUS From: WORKPLAN SPECIFICATIONS FOR PROPOSALS TO CONDUCT A FEASIBILITY STUDY FOR VARIOUS MANAGEMENT OPTIONS OF INVASIVE AQUATIC WEEDS, LAKE TAHOE, CALIFORNIA & NEVADA - Prepared MANAGEMENT OPTIONS OF INVASIVE AQUATIC WEEDS, LAKE TAHOE, CALIFORNIA & NEVADA - Prepared For: Department of the Army, United States Army Corps of Engineers, Sacramento DistrictFor: Department of the Army, United States Army Corps of Engineers, Sacramento District

Effectiveness and Effectiveness and DurationDuration• Diver hand-pulling, assisted by vacuum suction removal, can Diver hand-pulling, assisted by vacuum suction removal, can

be highly effective under appropriate conditions. Removal be highly effective under appropriate conditions. Removal efficiency depends on sediment condition, density of aquatic efficiency depends on sediment condition, density of aquatic plants, and underwater visibility. This technique works well to plants, and underwater visibility. This technique works well to control early low-level infestations of EWM or other aquatic control early low-level infestations of EWM or other aquatic weed species.weed species.

• This technique immediately clears the water column of This technique immediately clears the water column of nuisance plants and is site and species specific. A high degree nuisance plants and is site and species specific. A high degree of control, lasting more than one season, is possible when of control, lasting more than one season, is possible when complete removal has been achieved. It is most useful in complete removal has been achieved. It is most useful in hard-to-reach places and in sensitive areas where disruption hard-to-reach places and in sensitive areas where disruption of sediments must be minimized. Plant parts are collected for of sediments must be minimized. Plant parts are collected for later disposal, minimizing the spread of fragments, important later disposal, minimizing the spread of fragments, important for milfoil control. The vacuum assistance helps a diver cover for milfoil control. The vacuum assistance helps a diver cover a much larger area than ‘unassisted’ hand-pulling, and works a much larger area than ‘unassisted’ hand-pulling, and works well in soft sediments. Potential turbidity increases and well in soft sediments. Potential turbidity increases and bottom disruption depend on hydrosoil structure, and are bottom disruption depend on hydrosoil structure, and are usually confined and short-term.usually confined and short-term.

Regional Transport Regional Transport PerspectivePerspective

Physical ControlPhysical Control• Hand-harvesting with divers and rake-harvesting are viable Hand-harvesting with divers and rake-harvesting are viable

options for eliminating smaller populations of invasive aquatic options for eliminating smaller populations of invasive aquatic weeds. The use of water level alterations, shade barriers, bottom weeds. The use of water level alterations, shade barriers, bottom barriers and suspended blocking have been used to some extent barriers and suspended blocking have been used to some extent at Lake Tahoe and in other areas to control invasive aquatic weed at Lake Tahoe and in other areas to control invasive aquatic weed populations. populations.

• From the diver’s perspective in working on both sites in 2006, we From the diver’s perspective in working on both sites in 2006, we have found that we can be very effective with hand removal. It have found that we can be very effective with hand removal. It doesn’t disturb the bottom substrate as much as we thought it doesn’t disturb the bottom substrate as much as we thought it would. The turbidity that we create by pulling the roots is very would. The turbidity that we create by pulling the roots is very little compared to the turbidity we create just with our fin motion little compared to the turbidity we create just with our fin motion on the bottom.on the bottom.

• The effectiveness of hand-harvesting physical control has shown The effectiveness of hand-harvesting physical control has shown to have little if no potential effects on other Lake species or the to have little if no potential effects on other Lake species or the lake bottom. Diver’s are most effective at the hand-harvesting lake bottom. Diver’s are most effective at the hand-harvesting when we can place approximately 10 pounds of debris in each when we can place approximately 10 pounds of debris in each goodie bag. Without constant surfacing, divers can pile the bags goodie bag. Without constant surfacing, divers can pile the bags into one or several areas on the lake bottom and then retrieve into one or several areas on the lake bottom and then retrieve them with a float bag at one time to haul them onto a vesselthem with a float bag at one time to haul them onto a vessel

II. II. Diver-Assisted Hand RemovalDiver-Assisted Hand Removal

• Divers will remove as much EWM biomass as Divers will remove as much EWM biomass as possible within the designated time in a manner possible within the designated time in a manner that will minimize escape of fragments during that will minimize escape of fragments during initial collection, and dedicate time to gather the initial collection, and dedicate time to gather the majority of floating fragments, as reasonably majority of floating fragments, as reasonably practicable before the close of each day’s removal practicable before the close of each day’s removal operation. operation.

• Divers will assist in tracking effort, including Divers will assist in tracking effort, including recording the estimated volume of haul-out. recording the estimated volume of haul-out. Disposal refuse site will weigh each load taken Disposal refuse site will weigh each load taken from the transfer site, and relay weights to from the transfer site, and relay weights to contracting agency within one day after disposal.contracting agency within one day after disposal.

• Turbidity will be monitored by designated staff Turbidity will be monitored by designated staff pre-, during, and post-project removal activity.pre-, during, and post-project removal activity.

Hand HarvestingHand Harvesting

Mechanical ControlMechanical Control

• Mechanical control methods include Mechanical control methods include mechanical harvesting, wind-powered mechanical harvesting, wind-powered circulators (windmills), cutting, rotovation, circulators (windmills), cutting, rotovation, and rototilling. As early as the 1980's, and rototilling. As early as the 1980's, Tahoe boat marinas have employed the Tahoe boat marinas have employed the use of large-scale mechanical harvesters use of large-scale mechanical harvesters in weed infested areas. The use of such in weed infested areas. The use of such equipment may temporarily reduce plant equipment may temporarily reduce plant biomass in localized areas, but has the biomass in localized areas, but has the potential to exacerbate the spreading of potential to exacerbate the spreading of invasive aquatic weed species. Divers invasive aquatic weed species. Divers have looked into the use and effectiveness have looked into the use and effectiveness of large scale harvesting equipment and of large scale harvesting equipment and decided that for this project they would decided that for this project they would not be cost effective or efficient for any not be cost effective or efficient for any use in either Emerald Bay or Ski Run use in either Emerald Bay or Ski Run Marina.Marina.

Mechanical HarvestingMechanical Harvesting

Certification ProgramCertification Program• The Tahoe Divers Conservancy has instituted a Invasive The Tahoe Divers Conservancy has instituted a Invasive

Aquatic Plant Diver Certification program for this project.Aquatic Plant Diver Certification program for this project.• Invasive Aquatic Plant Diver Certification - PADIInvasive Aquatic Plant Diver Certification - PADI• Certification OutlineCertification Outline - Distinctive Specialty Course- Distinctive Specialty Course• ChapterTitleAuthorChapterTitleAuthor• I.Course Overview Phil/DougI.Course Overview Phil/Doug• II.Course Requirements Phil/Sharon/DougII.Course Requirements Phil/Sharon/Doug• III.Student and Instructor Equipment Requirements III.Student and Instructor Equipment Requirements

Phil/Sharon/DougPhil/Sharon/Doug• IV.Academics* Phil/Karl/DougIV.Academics* Phil/Karl/Doug• V.General Open-Water Considerations Phil/James/DougV.General Open-Water Considerations Phil/James/Doug• VI.Open-Water Sessions Phil/Sharon/DougVI.Open-Water Sessions Phil/Sharon/Doug• AppendixGeneral Phil/DougAppendixGeneral Phil/Doug• *referencing the PADI Instructors manual on Section II.*referencing the PADI Instructors manual on Section II.

Underwater SlatesUnderwater Slates

Help Stop the Alien Help Stop the Alien Invasion Invasion Extermination Techniques:Extermination Techniques:

Are you providing free rides to aliens? Don't be an alien helper, Are you providing free rides to aliens? Don't be an alien helper, watch out for hitchhikers. Zebra mussels have already invaded the watch out for hitchhikers. Zebra mussels have already invaded the Great Lakes and the Mississippi River. Other lakes and streams in Great Lakes and the Mississippi River. Other lakes and streams in Wisconsin are at risk. Check the ways you think zebra mussels can Wisconsin are at risk. Check the ways you think zebra mussels can get from one body of water to another. get from one body of water to another.

• Boaters use their boats in several places without cleaning them Boaters use their boats in several places without cleaning them with hot water. with hot water.

• Kids, mucking in a lake, slosh over to a different lake and empty Kids, mucking in a lake, slosh over to a different lake and empty out their boots. out their boots.

• Anglers take their bait buckets from lakes to rivers and empty Anglers take their bait buckets from lakes to rivers and empty them into the waters. them into the waters.

• Someone gets bored with a pet zebra mussel and releases it in a Someone gets bored with a pet zebra mussel and releases it in a new home. new home.

• Ducks, with muddy feet, fly off to new watery homes. Ducks, with muddy feet, fly off to new watery homes. • Water plants get stuck on boats or other equipment and are Water plants get stuck on boats or other equipment and are

carried to different bodies of water. carried to different bodies of water.

REFERENCESREFERENCES • Anderson, LWJ and DF Spencer. 1995. Survey of Lake Tahoe for presence ofAnderson, LWJ and DF Spencer. 1995. Survey of Lake Tahoe for presence of• Eurasianwatermilfoil. Eurasianwatermilfoil. InIn. USDA/ARS Annual Report, Aquatic Weed Control Investigations. p. 27-32.. USDA/ARS Annual Report, Aquatic Weed Control Investigations. p. 27-32.• Anderson, Lars W.J. The Invasion of Eurasian watermilfoil (Anderson, Lars W.J. The Invasion of Eurasian watermilfoil (Myriophyllum spicatumMyriophyllum spicatum) and Curlyleaf pondweed ) and Curlyleaf pondweed

((Potamogeton crispusPotamogeton crispus))• in Lake Tahoe: The Risks of Benign Neglect.in Lake Tahoe: The Risks of Benign Neglect.• Anderson, LWJ and DF Spencer. 1996. Survey of Lake Tahoe for presence ofAnderson, LWJ and DF Spencer. 1996. Survey of Lake Tahoe for presence of• Eurasianwatermilfoil. Eurasianwatermilfoil. InIn. USDA/ARS Annual Report, Aquatic Weed Control Investigations. p. 52-56.. USDA/ARS Annual Report, Aquatic Weed Control Investigations. p. 52-56.• Anderson, LWJ 1997. Myriophyllum spicatum at Lake Tahoe: Spirng and late summerpopulations outside the Tahoe Keys Anderson, LWJ 1997. Myriophyllum spicatum at Lake Tahoe: Spirng and late summerpopulations outside the Tahoe Keys

Marina. Marina. InIn. USDA/ARS Annual Report, Aquatic Weed Control Investigations. p. 59.. USDA/ARS Annual Report, Aquatic Weed Control Investigations. p. 59.• Anderson, Lars W.J. Clarification on Corps & Proposed Milfoil Study. E-mail. 10-01-06.Anderson, Lars W.J. Clarification on Corps & Proposed Milfoil Study. E-mail. 10-01-06.• Aquatic Invasive Species: Curlyleaf Pondweed. The State of Indiana Department of Natural Resources.Aquatic Invasive Species: Curlyleaf Pondweed. The State of Indiana Department of Natural Resources.• http://http://www.in.gov/dnr/invasivespecies/CURLYLEAFPONDWEED.pdfwww.in.gov/dnr/invasivespecies/CURLYLEAFPONDWEED.pdf• California Invasive Plant Council: California Invasive Plant Council: Myriophyllum spicatumMyriophyllum spicatum. The University of California at Davis. . The University of California at Davis. Http://Http://

ucce.ucdavis.edu/datastore/detailreport.cfmucce.ucdavis.edu/datastore/detailreport.cfm• Chandra, S. 2003. The impact of nonnative species and cultural eutrophication on the Lake Tahoe food web over time. Chandra, S. 2003. The impact of nonnative species and cultural eutrophication on the Lake Tahoe food web over time.

PhD thesis. University of California, Davis.PhD thesis. University of California, Davis.• Invasive Plant Species: Eurasian Water Milfoil (Myriophyllum spicatum). Wisconsin Department of Natural Resources. Invasive Plant Species: Eurasian Water Milfoil (Myriophyllum spicatum). Wisconsin Department of Natural Resources.

http://www.dnr.state.wi.us/invasives/fact/milfoil.htmhttp://www.dnr.state.wi.us/invasives/fact/milfoil.htm• Land and Resource Management Plan, Comprehensive Evaluation Report: Lake Tahoe Management Unit. United States Land and Resource Management Plan, Comprehensive Evaluation Report: Lake Tahoe Management Unit. United States

Department of Agriculture: Forest Service.Department of Agriculture: Forest Service.• Non-Native Freshwater Plants: Eurasian Milfoil. Washington State Department of Ecology. Non-Native Freshwater Plants: Eurasian Milfoil. Washington State Department of Ecology. http://http://

www.ecy.wa.gov/programs/wq/plants/weeds/milfoil.htmlwww.ecy.wa.gov/programs/wq/plants/weeds/milfoil.html• Plant Conservation Alliance: Eurasian Watermilfoil. National Park Service. Plant Conservation Alliance: Eurasian Watermilfoil. National Park Service.

http://www.nps.gov/plants/alien/fact/msp1.htmlhttp://www.nps.gov/plants/alien/fact/msp1.html• Policy and Planning Guidance for Conducting Civil Works Planning Studies. U.S. Army Corps of Engineers. December 28, Policy and Planning Guidance for Conducting Civil Works Planning Studies. U.S. Army Corps of Engineers. December 28,

1990.1990.• Progress Report: Federal Actions At Lake Tahoe; FY 2003-2005. Lake Tahoe Intragency Partnership. May 2006.Progress Report: Federal Actions At Lake Tahoe; FY 2003-2005. Lake Tahoe Intragency Partnership. May 2006.• San Francisco Estuary Institute, April 2004. Aquatic Pesticide Monitoring Program, Review of Aquatic Pest Control San Francisco Estuary Institute, April 2004. Aquatic Pesticide Monitoring Program, Review of Aquatic Pest Control

Monitoring Methods For California Waters.Monitoring Methods For California Waters.• Spencer, DF and J Madsen. 1996. Eurasian watermilfoil in Lake Tahoe and the Truckee River. In USDA/ARS Annual Spencer, DF and J Madsen. 1996. Eurasian watermilfoil in Lake Tahoe and the Truckee River. In USDA/ARS Annual

Report Aquatic Report Aquatic • Weed Investigations. P. 57-59.Weed Investigations. P. 57-59.• Vander Zanden, S Chandra, BC Allen, JE Reuter, & CR Goldman. 2003. Historical food web structure and restoration of Vander Zanden, S Chandra, BC Allen, JE Reuter, & CR Goldman. 2003. Historical food web structure and restoration of

native fish communities in Lake Tahoe (CA-NV) basin. Ecosystemsnative fish communities in Lake Tahoe (CA-NV) basin. Ecosystems 3: 274-288.3: 274-288.• Vanni, MJ, KK Arend, MT Bremigan, DB Bunnell, JE Garvey, MJ González, WH Renwick, PA Soranno, and RA Stein. 2005. Vanni, MJ, KK Arend, MT Bremigan, DB Bunnell, JE Garvey, MJ González, WH Renwick, PA Soranno, and RA Stein. 2005.

Linking landscapes and food webs: effects of omnivorous fish and watersheds on reservoir ecosystems. BioScience 55: Linking landscapes and food webs: effects of omnivorous fish and watersheds on reservoir ecosystems. BioScience 55: 155–167.155–167.

• Washington State Department of Ecology. Aquatic Vegetation Survey Methods. Washington State Department of Ecology. Aquatic Vegetation Survey Methods. www.ecy.wa.gov/programs/wq/plants/management/survey.htmlwww.ecy.wa.gov/programs/wq/plants/management/survey.html..

Other InvasivesOther Invasives

Zebra MusselZebra Mussel

• • Alias (scientific name in Latin):Alias (scientific name in Latin): Dreissena polymorpha Dreissena polymorpha • Home Land (Origination):Home Land (Origination): Ponto-Caspian region of western Ponto-Caspian region of western

Russia Russia • Arrival Date:Arrival Date: They were first found in the Great Lakes on June 1, They were first found in the Great Lakes on June 1,

1988. They were accidentally introduced to North America in 1988. They were accidentally introduced to North America in ballast water from a boat that traveled across the ocean.ballast water from a boat that traveled across the ocean.

• • How to Identify:How to Identify:

Polymorpha, means "many forms." Zebra mussels come in many Polymorpha, means "many forms." Zebra mussels come in many colors. Most are white or cream-colored with jagged brown or black colors. Most are white or cream-colored with jagged brown or black stripes. However, some individual mussels have been found that stripes. However, some individual mussels have been found that are all-white, all-black, or have stripes going the other direction. are all-white, all-black, or have stripes going the other direction. Zebra mussels are members of the phylum Mollusca (mol-US-ka), Zebra mussels are members of the phylum Mollusca (mol-US-ka), or mollusks. Mollusca comes from the Latin word, mollis, meaning or mollusks. Mollusca comes from the Latin word, mollis, meaning soft. Slugs, snails, octopuses, clams, and oysters are all mollusks. soft. Slugs, snails, octopuses, clams, and oysters are all mollusks. Mussels are bivalve mollusks. Bivalves have two shells that are Mussels are bivalve mollusks. Bivalves have two shells that are held together by a strong ligament. held together by a strong ligament.

Dynamic MappingDynamic Mapping http://nationalatlas.gov/dynamic/dyn_zm.html#http://nationalatlas.gov/dynamic/dyn_zm.html#

Rapid Spread of Zebra Rapid Spread of Zebra MusselsMussels

Attack on Native EcosystemAttack on Native Ecosystem

Truckee River WatershedTruckee River Watershed

Zebra Mussel vs. 2 Inch PipeZebra Mussel vs. 2 Inch Pipe

Life CycleLife Cycle

Zebra Mussel TrapZebra Mussel Trap

Mussel Monthly Check-upMussel Monthly Check-up

Web Based On Line Reporting Web Based On Line Reporting FormForm

Caspian Area of InvasivesCaspian Area of Invasives

New Zealand MudsnailNew Zealand Mudsnail

Spread of Mud Snail Spread of Mud Snail in Western States in Western States

Crayfish kill-offCrayfish kill-off

Spread in One Decade Spread in One Decade

Nevada CountiesNevada Counties

Spread in the Great BasinSpread in the Great Basin

Effected California AreasEffected California Areas

polymorhpa vs. bugensispolymorhpa vs. bugensis

Variations Variations

polymorhpa vs. bugensispolymorhpa vs. bugensis

Tahoe Divers Conservancy Tahoe Divers Conservancy Green Boat ProjectGreen Boat Project

• Design specification to log over 24,000 Design specification to log over 24,000 operational hours as the primary vessel serving operational hours as the primary vessel serving as the TDC research and work platform while as the TDC research and work platform while

monitoring the marine resources of Lake Tahoe.monitoring the marine resources of Lake Tahoe. • During the 20 year life of the vessel it is During the 20 year life of the vessel it is

estimated that we will use 185,000 gallons of estimated that we will use 185,000 gallons of diesel fuel. To reduce the environmental impact diesel fuel. To reduce the environmental impact of this operation several changes are proposed:of this operation several changes are proposed:

• Use of bio-diesel fuels only.Use of bio-diesel fuels only.

• Lubricating Oils- Only re-refined oil is utilized on Lubricating Oils- Only re-refined oil is utilized on the boat, this oil reduces the need to exploit new the boat, this oil reduces the need to exploit new oil resources.oil resources. Additionally the oil filter system on Additionally the oil filter system on the boat, a "Purafiner" system super cleans the the boat, a "Purafiner" system super cleans the engine oil while removing contaminants which engine oil while removing contaminants which reduced oil change cycles by 78%.reduced oil change cycles by 78%.

• Electrical Generation- Battery storage and a 110/220 Electrical Generation- Battery storage and a 110/220 volt inverter provide cabin electrical service which volt inverter provide cabin electrical service which has reduced generator run time by 65%.has reduced generator run time by 65%.

• Bulbous Bow- Hull modifications to the vessel are Bulbous Bow- Hull modifications to the vessel are proposed to be performed. The installation of a proposed to be performed. The installation of a "Bulbous Bow" reduces friction and wake resistance "Bulbous Bow" reduces friction and wake resistance on the displacement hull as it travels through the on the displacement hull as it travels through the water. This increased efficiency allows the vessel to water. This increased efficiency allows the vessel to travel farther while operating at the same engine travel farther while operating at the same engine RPM and fuel consumption. The predicted fuel RPM and fuel consumption. The predicted fuel savings will averaged 18%. This increase in savings will averaged 18%. This increase in efficiency will result in less fuel being consumed per efficiency will result in less fuel being consumed per trip and correspond in reduced exhaust emissions.trip and correspond in reduced exhaust emissions.

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