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• 1. [Article] Oregon Lake Watch, 2014 Annual Report

  The Oregon Lake Watch (OLW) volunteer monitoring program is now in its second year of operation, continuing its focus on early detection of aquatic invasive species (AIS), with a secondary focus on lake ...

  Citation × Citation Citation Abstract Copy Title: Oregon Lake Watch, 2014 Annual Report Author: Jordan, Meredith, Miller, Rich, Strecker, Angela L. Year: 2015 The Oregon Lake Watch (OLW) volunteer monitoring program is now in its second year of operation, continuing its focus on early detection of aquatic invasive species (AIS), with a secondary focus on lake water quality. The aquatic invasive species chosen as Watch List priorities for the OLW are based on the Oregon Department of Agriculture’s Noxious Weed List (Oregon Department of Agriculture Noxious Weed Control Program 2014) as well as professional judgement (more information can be found in Oregon Lake Watch Final Report 2014). This report summarizes the data collected by 15 of 24 OLW volunteers over 2014, across 110 sampling events and 20 Oregon lakes. Data collected by trained volunteers includes sightings of both native and aquatic invasive plants and animals, as well as recordings of lake temperature profiles, and Secchi depth, a measure of clarity. Of the 16 original water bodies surveyed in OLW’s first year (2013), 12 were surveyed again in 2014, and 8 are new waterbodies. Long-term monitoring of these lakes provides valuable information over time, and expanding the number of lakes monitored, especially in the case of monitoring for invasive species, means that more potentially harmful invasions can be stopped sooner. Ideally, the OLW will continue to monitor these current lakes, and expand their volunteer network to cover more waterbodies across Oregon as this program continues to grow. Title: Oregon Lake Watch, 2014 Annual Report Author: Jordan, Meredith, Miller, Rich, Strecker, Angela L. Year: 2015 The Oregon Lake Watch (OLW) volunteer monitoring program is now in its second year of operation, continuing its focus on early detection of aquatic invasive species (AIS), with a secondary focus on lake water quality. The aquatic invasive species chosen as Watch List priorities for the OLW are based on the Oregon Department of Agriculture’s Noxious Weed List (Oregon Department of Agriculture Noxious Weed Control Program 2014) as well as professional judgement (more information can be found in Oregon Lake Watch Final Report 2014). This report summarizes the data collected by 15 of 24 OLW volunteers over 2014, across 110 sampling events and 20 Oregon lakes. Data collected by trained volunteers includes sightings of both native and aquatic invasive plants and animals, as well as recordings of lake temperature profiles, and Secchi depth, a measure of clarity. Of the 16 original water bodies surveyed in OLW’s first year (2013), 12 were surveyed again in 2014, and 8 are new waterbodies. Long-term monitoring of these lakes provides valuable information over time, and expanding the number of lakes monitored, especially in the case of monitoring for invasive species, means that more potentially harmful invasions can be stopped sooner. Ideally, the OLW will continue to monitor these current lakes, and expand their volunteer network to cover more waterbodies across Oregon as this program continues to grow. Close

• 2. [Article] Oregon Lake Watch, 2015 Annual Report

  The Oregon Lake Watch (OLW) volunteer monitoring program completed its third year of operation during 2015 with a focus on early detection of aquatic invasive species (AIS) and water quality status and ...

  Citation × Citation Citation Abstract Copy Title: Oregon Lake Watch, 2015 Annual Report Author: Cimino, Samuel, Miller, Rich, Strecker, Angela L. Year: 2015 The Oregon Lake Watch (OLW) volunteer monitoring program completed its third year of operation during 2015 with a focus on early detection of aquatic invasive species (AIS) and water quality status and trend assessments for the better management of Oregon’s lakes and reservoirs. AIS surveys emphasized the detection of Watch List aquatic plant and species that can have a negative impacts on the beneficial uses of our waterbodies. Water transparency and temperature measurements were used to track the condition of volunteers' lakes. Thirty-one Oregon lakes have been surveyed during the OLW’s three years, 16 of which were surveyed during 2015. Seven lakes have been surveyed all three years and seven more have been surveyed two of the three years. Four Watch List plant and one animal species were found during 2015. Eurasian watermilfoil (Myriophyllum spicatum) was found in three lakes, Brazilian elodea (Egeria densa) and curly leaf pondweed (Potamogeton crispus) were each found in two lakes, and yellow flag iris (Iris pseudacorus) was found in one lake. Asian clams (Corbicula fluminea) were found in one lake. A diverse array of native plants were found along with native signal crayfish (Pacifasticus leniusculus). Water quality ranged from eutrophic to oligotrophic conditions based on water transparency and water temperatures ranged as high as 28°C (82°F). More years of data collection are necessary to track water quality trends. Title: Oregon Lake Watch, 2015 Annual Report Author: Cimino, Samuel, Miller, Rich, Strecker, Angela L. Year: 2015 The Oregon Lake Watch (OLW) volunteer monitoring program completed its third year of operation during 2015 with a focus on early detection of aquatic invasive species (AIS) and water quality status and trend assessments for the better management of Oregon’s lakes and reservoirs. AIS surveys emphasized the detection of Watch List aquatic plant and species that can have a negative impacts on the beneficial uses of our waterbodies. Water transparency and temperature measurements were used to track the condition of volunteers' lakes. Thirty-one Oregon lakes have been surveyed during the OLW’s three years, 16 of which were surveyed during 2015. Seven lakes have been surveyed all three years and seven more have been surveyed two of the three years. Four Watch List plant and one animal species were found during 2015. Eurasian watermilfoil (Myriophyllum spicatum) was found in three lakes, Brazilian elodea (Egeria densa) and curly leaf pondweed (Potamogeton crispus) were each found in two lakes, and yellow flag iris (Iris pseudacorus) was found in one lake. Asian clams (Corbicula fluminea) were found in one lake. A diverse array of native plants were found along with native signal crayfish (Pacifasticus leniusculus). Water quality ranged from eutrophic to oligotrophic conditions based on water transparency and water temperatures ranged as high as 28°C (82°F). More years of data collection are necessary to track water quality trends. Close

• 3. [Article] OSMB Final Report, Task 7: Online Atlas of Oregon Lakes - Aquatic Invasive Species Interface

  In order to educate a broad cross section of the public about Aquatic Invasive Species (AIS) distributions and survey efforts in Oregon’s lakes and reservoirs, database connections were created to display ...

  Citation × Citation Citation Abstract Copy Title: OSMB Final Report, Task 7: Online Atlas of Oregon Lakes - Aquatic Invasive Species Interface Author: Miller, Rich, Sytsma, Mark D. Year: 2014 In order to educate a broad cross section of the public about Aquatic Invasive Species (AIS) distributions and survey efforts in Oregon’s lakes and reservoirs, database connections were created to display AIS information on the Online Atlas of Oregon Lakes (aol.research.pdx.edu/). The connections allowed for the dynamic display of AIS survey records stored in three separate databases: the Center for Lakes and Reservoir’s Oregon Aquatic Plant and Mussel Databases and the iMapInvasives database. AIS survey records collected by the Center for Lakes and Reservoirs were also reported to the iMapInvasives database. Title: OSMB Final Report, Task 7: Online Atlas of Oregon Lakes - Aquatic Invasive Species Interface Author: Miller, Rich, Sytsma, Mark D. Year: 2014 In order to educate a broad cross section of the public about Aquatic Invasive Species (AIS) distributions and survey efforts in Oregon’s lakes and reservoirs, database connections were created to display AIS information on the Online Atlas of Oregon Lakes (aol.research.pdx.edu/). The connections allowed for the dynamic display of AIS survey records stored in three separate databases: the Center for Lakes and Reservoir’s Oregon Aquatic Plant and Mussel Databases and the iMapInvasives database. AIS survey records collected by the Center for Lakes and Reservoirs were also reported to the iMapInvasives database. Close

• 4. [Article] Middle Columbia River Aquatic Nuisance Species Survey

  Aquatic nonindigenous species (ANS) in the middle Columbia and lower Snake rivers were surveyed during the summer of 2006. The project area included eight reservoirs and the free-flowing, Hanford Reach ...

  Citation × Citation Citation Abstract Copy Title: Middle Columbia River Aquatic Nuisance Species Survey Author: Draheim, Robyn, Sytsma, Mark D., Miller, Rich, Cordell, Jeffery Year: 2007 Aquatic nonindigenous species (ANS) in the middle Columbia and lower Snake rivers were surveyed during the summer of 2006. The project area included eight reservoirs and the free-flowing, Hanford Reach on the Columbia River. We also conducted a literature review to create a complete list of ANS for the study area. Title: Middle Columbia River Aquatic Nuisance Species Survey Author: Draheim, Robyn, Sytsma, Mark D., Miller, Rich, Cordell, Jeffery Year: 2007 Aquatic nonindigenous species (ANS) in the middle Columbia and lower Snake rivers were surveyed during the summer of 2006. The project area included eight reservoirs and the free-flowing, Hanford Reach on the Columbia River. We also conducted a literature review to create a complete list of ANS for the study area. Close

• 5. [Article] Waldo Lake Research in 2003

  This report summarizes the first year of an effort to develop a more complete understanding of the physical, chemical, and biological characteristics that drive the ecological processes of Waldo Lake. ...

  Citation × Citation Citation Abstract Copy Title: Waldo Lake Research in 2003 Author: Sytsma, Mark D., Rueter, John, Petersen, Richard, Koch, Roy, Wells, Scott A., Miller, Rich, Johnson, Laura, Annear, Robert Leslie Year: 2004 This report summarizes the first year of an effort to develop a more complete understanding of the physical, chemical, and biological characteristics that drive the ecological processes of Waldo Lake. Modern limnology recognizes the importance of watershed processes as well as in- lake processes in lake ecosystem functioning. Therefore, the approach included consideration of watershed hydrology and forcing functions that determine hydrodynamics of the system as well physical and chemical factors that may be important in regulating primary production in the lake. Data collected since 1998 was summarized and bathymetry of the basin was mapped using state-of-the-art digital depth sounding and GPS technology. A hypothesis that UV light may play an important role in regulating phytoplankton efficiency was examined in an effort to move toward more hypothesis-driven investigations to elucidate the factors controlling productivity. A Quality Assurance/Quality Control Plan was developed to guide data collection for long-term monitoring of the lake. Lastly, initial steps were made in the development of a model of lake hydrodynamics and primary production to aid in integration of the physical, chemical, and biological data that has been collected on the lake. Title: Waldo Lake Research in 2003 Author: Sytsma, Mark D., Rueter, John, Petersen, Richard, Koch, Roy, Wells, Scott A., Miller, Rich, Johnson, Laura, Annear, Robert Leslie Year: 2004 This report summarizes the first year of an effort to develop a more complete understanding of the physical, chemical, and biological characteristics that drive the ecological processes of Waldo Lake. Modern limnology recognizes the importance of watershed processes as well as in- lake processes in lake ecosystem functioning. Therefore, the approach included consideration of watershed hydrology and forcing functions that determine hydrodynamics of the system as well physical and chemical factors that may be important in regulating primary production in the lake. Data collected since 1998 was summarized and bathymetry of the basin was mapped using state-of-the-art digital depth sounding and GPS technology. A hypothesis that UV light may play an important role in regulating phytoplankton efficiency was examined in an effort to move toward more hypothesis-driven investigations to elucidate the factors controlling productivity. A Quality Assurance/Quality Control Plan was developed to guide data collection for long-term monitoring of the lake. Lastly, initial steps were made in the development of a model of lake hydrodynamics and primary production to aid in integration of the physical, chemical, and biological data that has been collected on the lake. Close

• 6. [Article] 2014 Aquatic Weed Surveys in Timothy Lake, Lake Harriet, North Fork Reservoir, Faraday Lake, and Estacada Lake

  The Clackamas River Hydroelectric Project No. 2195 (Project) is located on the Oak Grove Fork of the Clackamas River and the mainstem of the Clackamas River in Clackamas County, Oregon. Reservoirs included ...

  Citation × Citation Citation Abstract Copy Title: 2014 Aquatic Weed Surveys in Timothy Lake, Lake Harriet, North Fork Reservoir, Faraday Lake, and Estacada Lake Author: Miller, Rich, Sytsma, Mark D., Brittain, Jeffrey Thomas Year: 2014 The Clackamas River Hydroelectric Project No. 2195 (Project) is located on the Oak Grove Fork of the Clackamas River and the mainstem of the Clackamas River in Clackamas County, Oregon. Reservoirs included in the Project include Timothy Lake, Lake Harriet, North Fork Reservoir, Faraday Lake, and Estacada Lake. The operator of the Project, Portland General Electric (PGE), was issued a license on December 21, 2010 by the Federal Energy Regulatory Commission (FERC) for continued operations and maintenance. The Final Environmental Impact Statement (FEIS) for the license noted that regular surveys for invasive aquatic weed species would be conducted as part of the Project’s Vegetation Management Plan. The term “aquatic weed” is used here to refer to any non-native aquatic plant species. Information from repeated aquatic surveys will help determine native species distributions and the need for treatment of problematic aquatic weed species, particularly hydrilla (Hydrilla verticillata), Brazilian elodea (Egeria densa), and Eurasian watermilfoil (Myriophyllum spicatum). Surveys conducted for PGE by Portland State University (PSU) in Timothy Lake, Lake Harriet, and North Fork Reservoir in 2011 did not locate any problematic submerged or floating leaved aquatic weed species. Earlier surveys of Timothy Lake, and Timothy Lake and Lake Harriet, also indicated the reservoirs were free of aquatic weeds. Heaton et al. (1996) noted that the native species Bidens beckii was present and had the potential to become weedy, however, this species was not found during the 2004 or 2011 surveys. This report covers the results of follow up aquatic vegetation surveys conducted in Lake Harriet, Timothy Lake, and North Fork Reservoir between August 14 and August 21, 2014, as well as new surveys of Faraday Lake and Estacada Lake. Shoreline surveys for emergent invasive species such as yellow flag iris (Iris pseudacorus) and purple loosestrife (Lythrum salicaria) were included in surveys for the first time. Title: 2014 Aquatic Weed Surveys in Timothy Lake, Lake Harriet, North Fork Reservoir, Faraday Lake, and Estacada Lake Author: Miller, Rich, Sytsma, Mark D., Brittain, Jeffrey Thomas Year: 2014 The Clackamas River Hydroelectric Project No. 2195 (Project) is located on the Oak Grove Fork of the Clackamas River and the mainstem of the Clackamas River in Clackamas County, Oregon. Reservoirs included in the Project include Timothy Lake, Lake Harriet, North Fork Reservoir, Faraday Lake, and Estacada Lake. The operator of the Project, Portland General Electric (PGE), was issued a license on December 21, 2010 by the Federal Energy Regulatory Commission (FERC) for continued operations and maintenance. The Final Environmental Impact Statement (FEIS) for the license noted that regular surveys for invasive aquatic weed species would be conducted as part of the Project’s Vegetation Management Plan. The term “aquatic weed” is used here to refer to any non-native aquatic plant species. Information from repeated aquatic surveys will help determine native species distributions and the need for treatment of problematic aquatic weed species, particularly hydrilla (Hydrilla verticillata), Brazilian elodea (Egeria densa), and Eurasian watermilfoil (Myriophyllum spicatum). Surveys conducted for PGE by Portland State University (PSU) in Timothy Lake, Lake Harriet, and North Fork Reservoir in 2011 did not locate any problematic submerged or floating leaved aquatic weed species. Earlier surveys of Timothy Lake, and Timothy Lake and Lake Harriet, also indicated the reservoirs were free of aquatic weeds. Heaton et al. (1996) noted that the native species Bidens beckii was present and had the potential to become weedy, however, this species was not found during the 2004 or 2011 surveys. This report covers the results of follow up aquatic vegetation surveys conducted in Lake Harriet, Timothy Lake, and North Fork Reservoir between August 14 and August 21, 2014, as well as new surveys of Faraday Lake and Estacada Lake. Shoreline surveys for emergent invasive species such as yellow flag iris (Iris pseudacorus) and purple loosestrife (Lythrum salicaria) were included in surveys for the first time. Close

• 7. [Article] Aquatic Plant Surveys in the Bureau of Land Management, Medford District, 2010-2011

  The introduction of invasive aquatic plant species (IAPS) can cause significant ecological and economic harm. IAPS can displace native aquatic plant species, impair recreation, and degrade water quality. ...

  Citation × Citation Citation Abstract Copy Title: Aquatic Plant Surveys in the Bureau of Land Management, Medford District, 2010-2011 Author: Sytsma, Mark D., Miller, Rich, Morgan, Vanessa Year: 2011 The introduction of invasive aquatic plant species (IAPS) can cause significant ecological and economic harm. IAPS can displace native aquatic plant species, impair recreation, and degrade water quality. Early detection of new invasions can improve chances for successful eradication or containment to reduce the risk of IAPS spread. The Oregon Department of Agriculture (ODA) lists the most egregious offenders as “Noxious Weeds” which are defined as plants classified by the Oregon State Weed Board that are injurious to public health, agriculture, recreation, wildlife, or any public or private property (ODA 2011). Several IAPS classified as noxious have been detected within the Medford District of the Bureau of Land Management (BLM) in Southern Oregon including yellow floating heart (Nymphoides peltata) and yellow flag iris (Iris pseudacorus). During the summers of 2010 and 2011, IAPS surveys were conducted at selected reservoirs, lakes, and river boat launches within the Medford District to determine the extent of IAPS infestations as well as the distributions of native aquatic plant species. This report summarizes results of the surveys and provides recommendations for management of IAPS within the Medford District. Observations of any invasive aquatic animal species such as New Zealand mudsnails (Potamopyrgus antipodarum) are also reported. Title: Aquatic Plant Surveys in the Bureau of Land Management, Medford District, 2010-2011 Author: Sytsma, Mark D., Miller, Rich, Morgan, Vanessa Year: 2011 The introduction of invasive aquatic plant species (IAPS) can cause significant ecological and economic harm. IAPS can displace native aquatic plant species, impair recreation, and degrade water quality. Early detection of new invasions can improve chances for successful eradication or containment to reduce the risk of IAPS spread. The Oregon Department of Agriculture (ODA) lists the most egregious offenders as “Noxious Weeds” which are defined as plants classified by the Oregon State Weed Board that are injurious to public health, agriculture, recreation, wildlife, or any public or private property (ODA 2011). Several IAPS classified as noxious have been detected within the Medford District of the Bureau of Land Management (BLM) in Southern Oregon including yellow floating heart (Nymphoides peltata) and yellow flag iris (Iris pseudacorus). During the summers of 2010 and 2011, IAPS surveys were conducted at selected reservoirs, lakes, and river boat launches within the Medford District to determine the extent of IAPS infestations as well as the distributions of native aquatic plant species. This report summarizes results of the surveys and provides recommendations for management of IAPS within the Medford District. Observations of any invasive aquatic animal species such as New Zealand mudsnails (Potamopyrgus antipodarum) are also reported. Close

• 8. [Article] Aquatic Invasive Species Surveys of Upper Klamath Lake, Fourmile Lake, and Lake of the Woods, OR During 2012

  Three lakes located within the Klamath River Basin in Oregon (Upper Klamath Lake, Fourmile Lake, and Lake of the Woods) were surveyed for aquatic invasive species during the summer of 2012. Specimens were ...

  Citation × Citation Citation Abstract Copy Title: Aquatic Invasive Species Surveys of Upper Klamath Lake, Fourmile Lake, and Lake of the Woods, OR During 2012 Author: Miller, Rich, Sytsma, Mark D. Year: 2013 Three lakes located within the Klamath River Basin in Oregon (Upper Klamath Lake, Fourmile Lake, and Lake of the Woods) were surveyed for aquatic invasive species during the summer of 2012. Specimens were collected using plant rakes, benthic dredges, plankton nets, and crayfish traps. No invasive aquatic plants, gastropods, snails, bivalves or crayfish were detected in the lakes. Title: Aquatic Invasive Species Surveys of Upper Klamath Lake, Fourmile Lake, and Lake of the Woods, OR During 2012 Author: Miller, Rich, Sytsma, Mark D. Year: 2013 Three lakes located within the Klamath River Basin in Oregon (Upper Klamath Lake, Fourmile Lake, and Lake of the Woods) were surveyed for aquatic invasive species during the summer of 2012. Specimens were collected using plant rakes, benthic dredges, plankton nets, and crayfish traps. No invasive aquatic plants, gastropods, snails, bivalves or crayfish were detected in the lakes. Close

• 9. [Article] Aquatic Invasive Plant Surveys in the BLM Medford District During 2012

  Aquatic plant surveys were conducted at 22 waterbodies located within the Bureau of Land Management’s Medford District during the summer of 2012. Sites included eleven lakes, ponds or reservoirs and six ...

  Citation × Citation Citation Abstract Copy Title: Aquatic Invasive Plant Surveys in the BLM Medford District During 2012 Author: Miller, Rich, Morgan, Vanessa, Sytsma, Mark D. Year: 2013 Aquatic plant surveys were conducted at 22 waterbodies located within the Bureau of Land Management’s Medford District during the summer of 2012. Sites included eleven lakes, ponds or reservoirs and six reaches along the Rogue and Applegate Rivers. Five sampling areas surveyed during 2010 and 2011 were revisited to determine the extent of known non-native species infestations, positively identify rare species, or verify the absence of an expected non-native species. Plant specimens were collected at up to 50 sites at each waterbody using plant rakes or by observation. The non-native submersed species curly leaf pondweed (Potamogeton crispus) and Eurasian x northern watermilfoil (Myriophyllum sibiricum x spicatum) were widespread throughout the District. Eurasian watermilfoil (Myriophyllum spicatum) was present at two sites. Emergent non-native aquatic species included parrotsfeather (Myriophyllum aquaticum), yellow flag iris (Iris pseudacorus), purple loosestrife (Lythrum salicaria), reed canary grass (Phalaris arundinaceae), floating primrose-willow (Ludwigia peploides) and slender waternymph (Najas gracillima). Title: Aquatic Invasive Plant Surveys in the BLM Medford District During 2012 Author: Miller, Rich, Morgan, Vanessa, Sytsma, Mark D. Year: 2013 Aquatic plant surveys were conducted at 22 waterbodies located within the Bureau of Land Management’s Medford District during the summer of 2012. Sites included eleven lakes, ponds or reservoirs and six reaches along the Rogue and Applegate Rivers. Five sampling areas surveyed during 2010 and 2011 were revisited to determine the extent of known non-native species infestations, positively identify rare species, or verify the absence of an expected non-native species. Plant specimens were collected at up to 50 sites at each waterbody using plant rakes or by observation. The non-native submersed species curly leaf pondweed (Potamogeton crispus) and Eurasian x northern watermilfoil (Myriophyllum sibiricum x spicatum) were widespread throughout the District. Eurasian watermilfoil (Myriophyllum spicatum) was present at two sites. Emergent non-native aquatic species included parrotsfeather (Myriophyllum aquaticum), yellow flag iris (Iris pseudacorus), purple loosestrife (Lythrum salicaria), reed canary grass (Phalaris arundinaceae), floating primrose-willow (Ludwigia peploides) and slender waternymph (Najas gracillima). Close

• 10. [Article] Hydroacoustic Survey and Point Sampling of Macrophytes In Diamond Lake 2009

  MaxDepth Aquatics, Inc. was contracted to conduct a hydroacoustic survey of macrophyte distribution in Diamond Lake in 2009. The survey essentially repeated surveys conducted in 2002 and 2007, allowing ...

  Citation × Citation Citation Abstract Copy Title: Hydroacoustic Survey and Point Sampling of Macrophytes In Diamond Lake 2009 Author: Eilers, Joseph, Eilers, Benn, Sytsma, Mark D., Miller, Rich Year: 2010 MaxDepth Aquatics, Inc. was contracted to conduct a hydroacoustic survey of macrophyte distribution in Diamond Lake in 2009. The survey essentially repeated surveys conducted in 2002 and 2007, allowing for a detailed assessment of conditions in 2009 and comparisons among previous years. In addition, Portland State University was contracted to conduct a depth stratified random point sample survey of macrophyte species presence and absence. The point sample survey was similar to surveys conducted in 2005 and 2007. The results of the 2009 hydroacoustic survey showed that macrophytes were widely distributed throughout the lake at depths less than 8 meters, although some shorter aggregations of macrophytes were found at depths down to 14 meters. Average canopy height corresponded closely to macrophyte density in 2009. The recent survey showed that macrophytes had extended deeper throughout the lake compared to 2002 and 2007 and that canopy height had increased substantially in some locations. The 2009 distribution showed that recolonization of the near shore areas was proceeding, albeit at a relatively slow pace since the lake drawdown completed in 2006. The maximum density of macrophytes in 2009 was found between 4 to 6 meters. Five macrophyte species, one macroalgal species, and filamentous algae were present in the 2009 random point survey. The occurrence rates of the macrophytes Elodea canadensis, Ceratophyllum demersum, and Potamogeton praelongus in 2009 were similar to 2005 and 2007 while Potamogeton pusillus occurrence increased and Myriophyllum verticillatum decreased. Macrophytes were present in a few samples greater than 9 meters; however, biomass, as measured by the fullness of a sampling rake, was highest between 2 and 6 meters. The comparison of the grab sampling conducted in August with the hydroacoustic survey in early September showed poor correspondence in macrophyte density obtained by the two methods. This is likely due to differences in spatial scales of collected samples (10 m2 grid for hydroacoustics compared to < 1 m2 grab samples), comparison of a continuous analytic tool (hydroacoustic) versus an ordinal ranking of density (rake), and possibly some changes in the macrophytes community between the two sampling dates. Title: Hydroacoustic Survey and Point Sampling of Macrophytes In Diamond Lake 2009 Author: Eilers, Joseph, Eilers, Benn, Sytsma, Mark D., Miller, Rich Year: 2010 MaxDepth Aquatics, Inc. was contracted to conduct a hydroacoustic survey of macrophyte distribution in Diamond Lake in 2009. The survey essentially repeated surveys conducted in 2002 and 2007, allowing for a detailed assessment of conditions in 2009 and comparisons among previous years. In addition, Portland State University was contracted to conduct a depth stratified random point sample survey of macrophyte species presence and absence. The point sample survey was similar to surveys conducted in 2005 and 2007. The results of the 2009 hydroacoustic survey showed that macrophytes were widely distributed throughout the lake at depths less than 8 meters, although some shorter aggregations of macrophytes were found at depths down to 14 meters. Average canopy height corresponded closely to macrophyte density in 2009. The recent survey showed that macrophytes had extended deeper throughout the lake compared to 2002 and 2007 and that canopy height had increased substantially in some locations. The 2009 distribution showed that recolonization of the near shore areas was proceeding, albeit at a relatively slow pace since the lake drawdown completed in 2006. The maximum density of macrophytes in 2009 was found between 4 to 6 meters. Five macrophyte species, one macroalgal species, and filamentous algae were present in the 2009 random point survey. The occurrence rates of the macrophytes Elodea canadensis, Ceratophyllum demersum, and Potamogeton praelongus in 2009 were similar to 2005 and 2007 while Potamogeton pusillus occurrence increased and Myriophyllum verticillatum decreased. Macrophytes were present in a few samples greater than 9 meters; however, biomass, as measured by the fullness of a sampling rake, was highest between 2 and 6 meters. The comparison of the grab sampling conducted in August with the hydroacoustic survey in early September showed poor correspondence in macrophyte density obtained by the two methods. This is likely due to differences in spatial scales of collected samples (10 m2 grid for hydroacoustics compared to < 1 m2 grab samples), comparison of a continuous analytic tool (hydroacoustic) versus an ordinal ranking of density (rake), and possibly some changes in the macrophytes community between the two sampling dates. Close