Lake Pocotopaug Lake and Watershed Restoration Evaluation ...

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water quality should focus on inputs from developed areas. Unstable soils and lack of functionfrom the existing storm water attenuation devices yield substantial solid and nutrient loading.There is no “smoking gun” in the watershed. Excessive nutrient concentrations are found in alltributaries and storm drains, although runoff from developed areas tends to provide the highestvalues. However, spring runoff seems to be more detrimental than summer runoff and themajor tributaries are suspect due to the higher portion of the load they contribute.Excessive external and possibly internal solid loading, and algal growth reduce in-lake waterclarity. Disturbance of sediments in the shallow basin could influence whole lake water clarity,could provide nutrients to support algal growth, and should be investigated as a potentialsource.Using the predictive curves and mathematical empirical models, Lake Pocotopaug shouldcurrently experience reduced phytoplankton density if it behaved more like other lakes. In otherwords, current phosphorus concentrations should be low enough to control algal growth, basedon empirical relationships established from data for many lakes. However, Lake Pocotopaugproduces more algae per unit of phosphorus than most other lakes, placing it on the fringe ofknown relationships between phosphorus and chlorophyll and chlorophyll and water clarity.Finding and managing the differences between Lake Pocotopaug and other lakes could beimportant to reducing excessive growths of algae.Phytoplankton and zooplankton communities in Lake Pocotopaug are less than ideal, and mayrepresent important differences from other lakes. Phytoplankton densities are typicallymoderate to high and zooplankton densities are relatively low. As a result, water clarity issometimes undesirable for recreational uses. Since phytoplankton are thriving at lowphosphorus concentrations, reducing TP alone (within reasonable constraints) may not achievedesired results; a top down control method supplementing phosphorus reduction may benecessary. Altering the fish community to have more predators and less planktivorous panfishcould increase zooplankton grazing on phytoplankton. The recent stocking of walleye couldproduce a desirable secondary affect, if the population is large enough and is not decimated byfishing too quickly.There was no information gathered from this study that provides a conclusive explanation ofpast fish kills and recent schooling behavior; more detailed fish investigation was beyond thescope of this project. Panfish may be looking for alternative food sources in the tributaries dueto low in-lake zooplankton density. Sediment-water quality interactions during the time ofdecreasing lake temperature may play a role. Sporadic inputs from certain tributaries could bestressing fish in some locations. Pockets of supercooled water could be a stressor. Contactwith over 30 fishery professionals from a range of states did not reveal any clear explanation,however, and the data on hand are insufficient to explain observations.Lake Pocotopaug Restoration Evaluation 90May 2002
Although some may argue that by appearance Lake Pocotopaug is eutrophic, it is classified asmesotrophic by the State of Connecticut, largely due to the low nutrient levels. Unfortunately,lowering nutrient levels may not be a realistic solution to Lake Pocotopaug’s low water clarity,given practical limits on such reductions. Certainly the maintenance of low phosphorus is aprerequisite for increasing water clarity, but it may not be the whole answer.Lake Pocotopaug Restoration Evaluation 91May 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,
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
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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