Lake Pocotopaug Lake and Watershed Restoration Evaluation ...

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TABLE 21 continued. MANAGEMENT OPTIONS FOR CONTROL OF ALGAEOPTION MODE OF ACTION ADVANTAGES DISADVANTAGESChemical controls9.c) Forms of diquat(6,7-dihydropyrido [1,2-2’,1’-c]pyrazinediium dibromide)♦♦♦♦Contact algaecideAbsorbed directly by cellsStrong oxidant; disrupts mostcellular functionsApplied as a liquid,sometimes in conjunction withcopper10) Phosphorus inactivation ♦ Typically salts of aluminum,iron or calcium are added tothe lake, as liquid or powder♦ Phosphorus in the treatedwater column is complexedand settled to the bottom ofthe lake♦ Phosphorus in uppersediment layer is complexed,reducing release fromsediment♦ Permanence of binding variesby binder in relation to redoxpotential and pH♦ Potential for use on inletstreams as well♦♦♦♦♦♦♦Moderate control of thick algalmats, used where copperalone is ineffectiveLimited toxicity to fish atrecommended dosagesRapid actionCan provide rapid, majordecrease in phosphorusconcentration in water columnCan minimize release ofphosphorus from sedimentMay remove other nutrientsand contaminants as well asphosphorusFlexible with regard to depth ofapplication and speed ofimprovement♦♦♦♦♦♦♦♦♦Non-selective in treated areaToxic to zooplankton atrecommended dosageInactivated by suspendedparticles; ineffective in muddywatersTime delays on use for watersupply, agriculture andrecreationPossible toxicity to fish andinvertebrates, especially byaluminum at low pHPossible release of phosphorusunder anoxia or extreme pHMay cause fluctuations in waterchemistry, especially pH, duringtreatmentPossible resuspension of floc inshallow areas with extremeturbulenceAdds to bottom sediment, buttypically an insignificant amountLake Pocotopaug Restoration Evaluation 116May 2002
TABLE 21 continued. MANAGEMENT OPTIONS FOR CONTROL OF ALGAEOPTION MODE OF ACTION ADVANTAGES DISADVANTAGESChemical controls11) Sediment oxidation ♦ Addition of oxidants, bindersand pH adjustors oxidizessediment♦ Binding of phosphorus isenhanced♦ Denitrification is stimulated12) Settling agents ♦ Closely aligned withphosphorus inactivation, butcan be used to reduce algaedirectly too♦ Lime, alum or polymersapplied, usually as a liquid orslurry♦ Creates a floc with algae andother suspended particles♦ Floc settles to bottom of lake♦ Re-application typicallynecessary at least once/yr13) Selective nutrient addition ♦ Ratio of nutrients changed byadditions of selected nutrients♦ Addition of non-limitingnutrients can changecomposition of algalcommunity♦ Processes such as settlingand grazing can then reducealgal biomass (productivitycan actually increase, butstanding crop can decline)♦♦♦♦♦♦♦♦♦♦Can reduce phosphorussupply to algaeCan alter N:P ratios in watercolumnMay decrease sedimentoxygen demandRemoves algae and increaseswater clarity without lysingmost cellsReduces nutrient recycling iffloc sufficientRemoves non-algal particlesas well as algaeMay reduce dissolvedphosphorus levels at the sametimeCan reduce algal levels wherecontrol of limiting nutrient notfeasibleCan promote non-nuisanceforms of algaeCan improve productivity ofsystem without increasedstanding crop of algae♦♦♦♦♦♦♦♦♦♦Possible impacts on benthicbiotaLongevity of effects not wellknownPossible source of nitrogen forblue-green algaePossible impacts on aquaticfaunaPossible fluctuations in waterchemistry during treatmentResuspension of floc possible inshallow, well-mixed watersPromotes increased sedimentaccumulationMay result in greater algalabundance through uncertainbiological responseMay require frequent applicationto maintain desired ratiosPossible downstream effectsLake Pocotopaug Restoration Evaluation 117May 2002
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LAKE POCOTOPAUGLAKE AND WATERSHEDRE
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11.3 Prevent algal blooms from occu
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LAYPERSON’S SYNOPSISLake Pocotopa
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The stocking of walleye in Lake Poc
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Lake Pocotopaug Restoration Evaluat
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Period Covered 1988• Pollution fr
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Recommendations included• Algacid
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Major EventDecember 1999 - Fish kil
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Table 5. Land Use from the CT DEP G
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Figure 4. Lake Pocotopaug Bathymetr
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Table 6. QA/QC on Water Quality Dat
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Soils - USDA at MAGIC UCONN Geograp
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Table 8. Water Quality Variables Me
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Phytoplankton samples were collecte
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where many measurements would have
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Figure 7. 2001 Temperature and Diss
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Table 10 continued. 2001 Lake Pocot
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phytoplankton biomass (Wetzel 1983)
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Figure 9. Annual June, July and Aug
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elow 7:1 occurred on September 22,
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Table 12. 2001 Dry and Wet Weather
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Table 12 continued. 2001 Dry and We
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were identified to genus and enumer
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Table 13 continued. 2001 Phytoplank
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Figure 10. 2001 Phytoplankton Bioma
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The late summer bloom of blue-green
Page 72 and 73: Table 15. 2001 Zooplankton DensityZ
Page 74 and 75: Table 16. 2001 Zooplankton BiomassZ
Page 76 and 77: 7.0 RELATIONSHIPS AND TRENDS7.1 Pre
Page 78 and 79: Figure 13. 1991-2001 Surface Water
Page 80 and 81: Figure 15. 2001 Surface and Mid-dep
Page 82 and 83: Figure 16. 1991-2001 Chlorophyll a
Page 84 and 85: Figure 18. 2001 Chlorophyll a vs. S
Page 86 and 87: Figure 20. 1991-2001 July and Augus
Page 88 and 89: Table 17. Empirical Model Calculati
Page 90 and 91: Table 18. Total Phosphorus Loading
Page 92 and 93: Table 19. Wet Weather Loading Summa
Page 94 and 95: With the best possible treatment of
Page 96 and 97: water quality should focus on input
Page 98 and 99: 10.0 MANAGEMENT NEEDS AND OBJECTIVE
Page 100 and 101: 11.2 Reducing Total Phosphorus and
Page 102 and 103: undeveloped forest land, an opportu
Page 104 and 105: Figure 22. Buffer Strips for Pollut
Page 106 and 107: Figure 23. Catch Basin with Sump an
Page 108 and 109: early spring to capture what appear
Page 110 and 111: Figure 26. Infiltration Systems.Lak
Page 112 and 113: Figure 27. Constructed Treatment We
Page 114 and 115: Chemical TreatmentIn-stream chemica
Page 116 and 117: TABLE 21. MANAGEMENT OPTIONS FOR CO
Page 118 and 119: TABLE 21 continued. MANAGEMENT OPTI
Page 130 and 131: 12.0 ADDITIONAL DATA NEEDSManagemen
Page 132 and 133: 13.0 RECOMMENDED MANAGEMENT PROGRAM
Page 134 and 135: this point, but as a rough guide, a
Page 136 and 137: 14.0 REFERENCESAd Hoc Lake Advisory
Page 138 and 139: Scheuler T.R., P.A. Kumble, & M.A.
Page 140 and 141: Appendix B:Supplemental Tables and
Page 142: Appendix D:Educational MaterialsLak
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