Funded Solely by Property Owners of Santa Clara County

1. Lake Chemistry Management Using a Solar-Powered CirculatorRMP Annual Mercury MeetingFebruary 5th, 2009 Funded Solely by Property Owners of Santa Clara County Draft Data Do Not Cite

2. Lake Chemistry 101 • Oxygen Demand α stratification period and consumption from aerobic decomposition of settling and deposited particulate organic matter • Oxygen Demand α byproducts of anaerobic decomposition of settling and deposited particulate organic matter (S2-, HS-, H2S, N2, T-NH3, CH4) • Settling and deposited particulate organic matter α Current/Past Primary Productivity • Primary Productivity α P • 1/P α DO • CH3Hg+α mass of SO42- reduced Draft Data Do Not Cite

3. Epilimnion Metalimnion Hypolimnion Draft Data Do Not Cite

4. Lake Chemistry 101 • Oxygen Demand α stratification period and consumption from aerobic decomposition of settling and deposited particulate organic matter • Oxygen Demand α byproducts of anaerobic decomposition of settling and deposited particulate organic matter (S2-, HS-, H2S, N2, T-NH3, CH4) • Settling and deposited particulate organic matter α Current/Past Primary Productivity • Primary Productivity α P • 1/P α DO • CH3Hg+α mass of SO42- reduced Draft Data Do Not Cite

5. ΔG DO >> NO3- > Mn4+ Fe3+ > SO42- > CO2/Acetate Draft Data Do Not Cite

6. Lake Chemistry Management Tool Box • Decrease Primary Production • Reduce Nutrient Input/Cycling • Satisfy Historic Debt (past deposition of organic matter) • Extend Duration of Oxic Conditions in Hypolimnion • Influence Primary Production to favor green algae over Cyanobacteria • Exploit Competitive Differences Draft Data Do Not Cite

7. Biomagnification of Methyl Mercury in the Food Web Draft Data Do Not Cite

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10. Increasing Hypolimnetic Oxygen Availability Hypothesis: Inhibiting blue-green algae blooms reduces BOD loading to bottom waters, thereby reducing hypolimnetic oxygen depletion via decomposition. Hypolimnetic circulation extends the period of Oxic decomposition thereby reducing historic debt and nutrient cycling. Draft Data Do Not Cite

11. Red = Detrimental Blue = Beneficial N & P Input + Quiescent, warm surface waters Buoyant blue-green algae have a competitive advantage for nutrients & light Blue-green algae bloom Draft Data Do Not Cite

12. Red = Detrimental Blue = Beneficial N & P Input + Quiescent, warm surface waters Buoyant blue-green algae have a competitive advantage for nutrients & light Adds N to lake through N2 fixation Cyanotoxins Blue-green algae bloom Not edible Lethal effects decrease biodiversity Surface scum& odors Sinks to bottom at death Taste & odor (MIB & geosmin) Adds BOD to sediments Decomposition Promotes anoxia Promotes fish kills at turnover Degrades fish spawning habitat Promotes sediment release of soluble P, Mn, Fe, H2S Draft Data Do Not Cite

13. Major requirements for blue-green algae blooms Nutrients (e.g., N & P) Suitable temperatures (typically warm) Sufficient light for photosynthesis Quiescent, stagnant waters Draft Data Do Not Cite

14. How to Prevent Blue-green Algae Blooms? • Nutrient Reduction: Difficult and costly for non-point sources, and does not necessarily affect algal speciation • Chemical applications/ Short-term benefit, can create copper resistant Sonic Lysing: algae. If bloom is large, cell lysing can cause taste and odor event. • Habitat disturbance Effective; but has been through circulation: difficult to achieve in larger lakes until recent technological capabilities Draft Data Do Not Cite

15. Red = Detrimental Blue = Beneficial N & P Input + Horizontally & vertically circulating epilimnetic (surface) waters Disrupts blue-greens’ habitat (eliminates competitive advantage) Preventsblue-green blooms Draft Data Do Not Cite

16. Red = Detrimental Blue = Beneficial N & P Input + Horizontally & vertically circulating epilimnetic (surface) waters Disrupts blue-greens’ habitat (eliminates competitive advantage) Oxidizes littoral sediments Prevents blue-green blooms Inhibits release of soluble P, Fe, Mn, & H2S Improves fish habitat for spawning Allows diatoms, greens, etc. (“good algae”) to grow Edible Increases secondary production (e.g., zooplankton & fish) Reduces chlorophyll a, pH, & total P Increases water clarity, biodiversity Reduces N & BOD inputs to sediments Reduces risk of seasonal fish kills Draft Data Do Not Cite

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20. Water Quality Effects of Hypolimnetic Circulation Draft Data Do Not Cite

21. Site 2 Comparison of Dissolved Oxygen Profiles Draft Data Do Not Cite

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23. Before Circulator Installed After Circulator Installed Note how both Phosphorus (TP) and Sulfate (SO4) cycling is reduced by the effects of circulation. Draft Data Do Not Cite

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26. ΔG DO >> NO3- > Mn4+ Fe3+ > SO42- > CO2/Acetate Draft Data Do Not Cite

27. Applied Studies Underway Draft Data Do Not Cite

28. Hypolimnetic Circulator to be Installed 2009 Hypolimnetic Circulator Installed May 20, 2006 Site 5 Depth ~8 Meters Site 1 Depth ~13 Meters Site 2 Depth ~11 Meters D Site 3/4 Depth ~8 Meters Hypolimnetic Circulator Installed March 31, 2007 Epilimnetic Circulator to be Installed 2009 Draft Data Do Not Cite Draft Data Do Not Cite

29. Three Epilimnetic Circulators Installed July 2007 Pilot Hypolimnetic Oxygenation System to be Installed 2009 Draft Data Do Not Cite

30. Almaden Reservoir One Hypolimnetic and Two Epilimnetic Circulators Installed April 2007 Source Reduction Project To Be Constructed 2009 Draft Data Do Not Cite