Lake Pocotopaug Lake and Watershed Restoration Evaluation ...

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LAYPERSON’S SYNOPSISLake Pocotopaug covers 512 acres in East Hampton, CT. Its watershed is less than five timesas large as the lake. As a consequence, limited water is delivered to the lake and the lake isflushed relatively infrequently. This means that pollutants entering the lake stay there a longtime and can have the maximum impact on lake condition. Although the watershed is mostlyforest, areas that have been developed as residential and recreational areas are mostly nearthe lake and have negative impacts on the lake by adding nutrients, bacteria and otherpollutants. Over the long term, these inputs have caused a build up of contaminants in the lakethat support algal blooms and low water clarity. The alum treatment of 2000-2001 inactivatedthese contaminants over the most critical part of the lake, but inputs associated with bigger rainevents and possibly recycling of contaminants in untreated parts of the lake can still supportalgal blooms and low water clarity. Additional watershed management is therefore needed.An unusual aspect of the Lake Pocotopaug system is that it supports algal blooms at a relativelylow fertility level. This means that management that might be adequate at other area lakes maynot eliminate undesirable conditions in Lake Pocotopaug. Watershed management musttherefore be especially effective in reducing pollutant inputs to achieve the desired results. Avariety of options have been reviewed, including minimizing sources of contaminants andtrapping contaminants as they move toward the lake. Sources of major concern include lawncare products; education and possible local ordinances are recommended to reduce their use inthis watershed. Methods to trap contaminants include systems that detain storm water, withpassage into the ground wherever possible. Natural processes will reduce the amount ofpollutants reaching the lake through such systems.Adding predatory fish (such as walleye) to the lake may also improve conditions, as these fisheat smaller fish that eat small invertebrates that eat algae. In other words, by increasing thebiomass of predatory fish, grazing pressure on algae can be increased and less algae will buildup in the lake. This strategy may not be sufficient by itself, but can supplement a strongwatershed management program that reduces overall fertility in the lake.Some additional monitoring in the lake and watershed is needed to address some unansweredquestions and to track progress. This is a complicated system with no easy solution to existingproblems, but Town actions to date are moving the lake in the right direction, and carefulcontinued management is expected to continue and expand this improvement.Lake Pocotopaug Restoration Evaluation iMay 2002
1.0 EXECUTIVE SUMMARYLake Pocotopaug has a surface area of approximately 512 acres and is a major resource forrecreation and aquatic life in East Hampton. The watershed is small relative to the size of thelake (
Page 2 and 3: LAKE POCOTOPAUGLAKE AND WATERSHEDRE
Page 4 and 5: 11.3 Prevent algal blooms from occu
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 38 and 39: Table 10 continued. 2001 Lake Pocot
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
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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
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Table 15. 2001 Zooplankton DensityZ
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Table 16. 2001 Zooplankton BiomassZ
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7.0 RELATIONSHIPS AND TRENDS7.1 Pre
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Figure 13. 1991-2001 Surface Water
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Figure 15. 2001 Surface and Mid-dep
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Figure 16. 1991-2001 Chlorophyll a
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Figure 18. 2001 Chlorophyll a vs. S
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Figure 20. 1991-2001 July and Augus
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Table 17. Empirical Model Calculati
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Table 18. Total Phosphorus Loading
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Table 19. Wet Weather Loading Summa
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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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12.0 ADDITIONAL DATA NEEDSManagemen
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13.0 RECOMMENDED MANAGEMENT PROGRAM
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this point, but as a rough guide, a
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14.0 REFERENCESAd Hoc Lake Advisory
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Scheuler T.R., P.A. Kumble, & M.A.
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Appendix B:Supplemental Tables and
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Appendix D:Educational MaterialsLak
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