Lake Roosevelt Aquatic Plant Inventory and Treatment Testing

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Lake Roosevelt Aquatic Plant Inventory and
Treatment Testing

• Mark Sytsma
• and
• Rich Miller
• Center for Lakes and Reservoirs
• Portland State University

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Lake Roosevelt treatment sites
Columbia River Arm
E. Hanson Harbor
Spokane River Arm
Porcupine Bay
W. Hanson Harbor
Riverview Court
Moccasin Bay
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Treatments

• Control
• Solarization
• Black plastic
• Clear plastic
• Rototilling
• Heat
• Benthic barrier

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Columbia River Arm Treatments
East Hanson Harbor
West Hanson Harbor
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Spokane River Arm Treatments
Moccasin Bay
Riverview Court
Porcupine Bay
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Solarization - black plastic
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Heat
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Rototilled
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Methods

• Navigate to random point
• Collect sample with rake
• Transfer to (lab) for sorting and weighing

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Treatments
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Species Occurrence
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Biomass by site
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Biomass by site
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Biomass by site and treatment(Mean 95 C.I.)

• Biomass 95 C.I.

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Community composition by site and treatment
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Preliminary conclusions

• Significant difference in biomass of aquatic
  plants between Spokane Arm and Columbia River Arm
  
• The native species Potomogeton richardsonii,
  Najas flexilus, P. pusillus, and Stuckenia
  pectinata were most common
• Introduced Myriophyllum spicatum was rare
• No significant difference between any treatment
  and control at an site

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Preliminary recommendations

• Sediment amendment with organic material
• Sediment application of fluridone (2 lb a.i./acre
  or 2.25 kg/ha) with precipitation as treatment
  variable

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Questions?
Potamogeton epihydrus