Lake Pocotopaug Lake and Watershed Restoration Evaluation ...

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Table 10 continued. 2001 Lake Pocotopaug In-lake Data Summary.Station StatisticTurb(NTU)pH(SU)Alka(mg/L)SpecificCond.(us/cm)TotalPhos(mg/L)Diss.Phos(mg/L)Secchi(ft)Phyto(ug/L)Chloroa (ug/L)Al(mg/L)Diss.Al(mg/L)As(mg/L)Cd(mg/L)Cr(mg/L)Cu Diss.Fe(mg/L) (mg/L)LP-2B MEAN 13.7 6.6 20.0 122 0.052 0.003 --- --- --- 0.794 0.010 0.000 0.000 0.001 0.006 0.010 0.002 0.014 0.027MAX 46.0 7.2 40.0 174 0.216 0.008 --- --- --- 0.794 0.010 0.000 0.000 0.001 0.006 0.010 0.002 0.014 0.027MIN 2.2 6.1 4.0 91 0.015 0.001 --- --- --- 0.794 0.010 0.000 0.000 0.001 0.006 0.010 0.002 0.014 0.027n 7 6 6 6 7 6 --- --- --- 1 1 1 1 1 1 1 1 1 1Ni(mg/L)Pb(mg/L)Zn(mg/L)LP-2 MEAN --- --- --- --- --- --- --- 6606 5.5 --- --- --- --- --- --- --- --- --- ---Inter. MAX --- --- --- --- --- --- --- 16584 11.7 --- --- --- --- --- --- --- --- --- ---MIN --- --- --- --- --- --- --- 2923 1.6 --- --- --- --- --- --- --- --- --- ---n --- --- --- --- --- --- --- 6 6 --- --- --- --- --- --- --- --- --- ---Total MEAN 5.1 6.9 11.0 109 0.023 0.003 6.6 5508 5.8 0.246 0.020 0.000 0.000 0.001 0.004 0.010 0.001 0.006 0.013MAX 46.0 8.5 40.0 174 0.216 0.008 9.8 16584 14.8 0.794 0.020 0.000 0.000 0.002 0.006 0.010 0.002 0.014 0.027MIN 1.1 6.1 4.0 90 0.005 0.001 3.3 890 1.5 0.036 0.020 0.000 0.000 0.000 0.003 0.010 0.000 0.003 0.004n 38 32 32 32 50 44 20 18 12 4 4 4 4 4 4 6 4 4 4.Lake Pocotopaug Restoration Evaluation 32May 2002
Alkalinity remained at constant low values (range 4-12 mg/l) at surface and mid-depths in LakePocotopaug in 2001 (Table 10). Bottom values were higher but averages did not exceed 20mg/L. Alkalinity values in 2001 were comparable to previous years. Alkalinity is a measure ofthe buffering capacity of water, its ability to absorb H + ions without major oscillations in pH thatmay impact the biota. Alkalinity values lower than 2 mg/l indicate no buffering capacity; valuesbetween 2 and 20 mg/l suggest limited buffering capacity. High buffering capacity exists foralkalinity values higher than ~50 mg/l. The low alkalinity in Lake Pocotopaug is consideredtypical range and does not suggest the occurrence of water quality problems at the lake orwatershed scale.Specific conductivity in 2001 ranged from 90 to 174 µS/cm (Table 10). Mean conductivityranged from 102 to 122 µS/cm. Again, higher values were recorded at the bottom. Conductivityis a measure of the ion concentration in the water, and indirectly of total dissolved solids. The100 µS/cm is considered the threshold below which a water body is likely to be nutrient-poor, asonly a small portion of the dissolved solids are nutrients. Contaminated or fertile lakes, wherenutrient-driven phytoplankton blooms are likely to occur, are characterized by higherconductivity readings (often above 300 µS/cm), although it is possible to have high conductivityand low fertility with a lot of non-nutrient solids.Water transparency is typically measured as SDT. SDT corresponds to the depth at which lightintensity is approximately 10% of the surface value (Wetzel 1983), thus approximatelydelimitating the range of the photic zone (i.e., where photosynthesis can occur). SDT isassociated with light scattering by particulate matter in suspension, including algae (Carlson1977; Wetzel 1983). SDT can be used as a general measure of lake condition, with depthsgreater than 4 m indicating desirable water quality and depths less than 1 m indicatingundesirable water quality (Carlson 1977). Carlson’s lower threshold is similar to theConnecticut’s Water Quality Standard for mesotrophic lakes (2 – 6 m during the summer).Water transparency or SDT in Lake Pocotopaug was less than desirable in 2001 (Table 10).Maximum SDT was 3 meters, below the 4 meter desirable threshold. Minimum transparencywas recorded at LP-2 in August (1 m). On average, SDT in 2001 was 2.1 and 1.9 meters forLP-1 and LP-2 respectively. LP-2 often has slightly lower transparencies than LP-1. Minimumtransparencies ranged from 0.4 to 1.7 meters from 1991-2000. Maximum transparencies frommid-May to mid-September in 1991-2000 ranged from 2.3 to 4.0 meters. The greatest SDTswere typically recorded during mid to the end of June (2001 was no exception). However,maximum transparency was recorded in early July in 1997, 1998 and 2000.Phosphorus is usually the nutrient limiting freshwater photosynthetic organisms, including algae(Hecky & Kilham 1988). Total phosphorus (TP) includes all forms of phosphorus in the watercolumn, from readily absorbable dissolved orthophosphates to refractory particulatephosphorus. TP is often used as a measure of a lake trophic state (Carlson 1977). Surface TPconcentrations below 0.01 mg/l are usually associated with clear water and lack of appreciableLake Pocotopaug Restoration Evaluation 33May 2002
Page 2 and 3: LAKE POCOTOPAUGLAKE AND WATERSHEDRE
Page 4 and 5: 11.3 Prevent algal blooms from occu
Page 6 and 7: LAYPERSON’S SYNOPSISLake Pocotopa
Page 8 and 9: The stocking of walleye in Lake Poc
Page 10 and 11: Lake Pocotopaug Restoration Evaluat
Page 12 and 13: Period Covered 1988• Pollution fr
Page 14 and 15: Recommendations included• Algacid
Page 16 and 17: Major EventDecember 1999 - Fish kil
Page 18 and 19: Table 5. Land Use from the CT DEP G
Page 22 and 23: Figure 4. Lake Pocotopaug Bathymetr
Page 24 and 25: Table 6. QA/QC on Water Quality Dat
Page 26 and 27: Soils - USDA at MAGIC UCONN Geograp
Page 28 and 29: Table 8. Water Quality Variables Me
Page 32 and 33: Phytoplankton samples were collecte
Page 34 and 35: where many measurements would have
Page 36 and 37: Figure 7. 2001 Temperature and Diss
Page 40 and 41: phytoplankton biomass (Wetzel 1983)
Page 42 and 43: Figure 9. Annual June, July and Aug
Page 44 and 45: elow 7:1 occurred on September 22,
Page 46 and 47: Table 12. 2001 Dry and Wet Weather
Page 48 and 49: Table 12 continued. 2001 Dry and We
Page 56 and 57: were identified to genus and enumer
Page 58 and 59: Table 13 continued. 2001 Phytoplank
Page 68 and 69: Figure 10. 2001 Phytoplankton Bioma
Page 70 and 71: 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
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water quality should focus on input
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10.0 MANAGEMENT NEEDS AND OBJECTIVE
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11.2 Reducing Total Phosphorus and
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undeveloped forest land, an opportu
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Figure 22. Buffer Strips for Pollut
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Figure 23. Catch Basin with Sump an
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early spring to capture what appear
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Figure 26. Infiltration Systems.Lak
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Figure 27. Constructed Treatment We
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Chemical TreatmentIn-stream chemica
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TABLE 21. MANAGEMENT OPTIONS FOR CO
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TABLE 21 continued. MANAGEMENT OPTI
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Page 124 and 125:
Page 126 and 127:
Page 128 and 129:
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12.0 ADDITIONAL DATA NEEDSManagemen
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13.0 RECOMMENDED MANAGEMENT PROGRAM
Page 134 and 135:
this point, but as a rough guide, a
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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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