Lake Pocotopaug Lake and Watershed Restoration Evaluation ...

More documents

Recommendations

Info

Table 18. Total Phosphorus Loading EstimatesSource Volume/Year 2001 TP (ug/L)TP LoadCalculated(kg/yr)Best Estimate(kg/yr)% of TotalDirect Precipitation 1 2.5 x 10 6 m 3 10 - 20 25 - 50 35 13 – 7Ground Water 2 0.5 - 0.9 x 10 6 m 3 10 - 20 5 - 18 12 4 – 2Surface Water 3 5.5 - 5.9 x 10 6 m 3Wet Weather 4 3.5 x 10 6 m 3 124 - 317 434 - 1110 126 – 322Dry Weather 5 2.0 - 2.4 x 10 6 m 3 19 - 50 38 - 120 15 – 48Total 141 - 370 50 – 73[Load Coeff] 6 [232 - 480][Mass Balance] 7 [280 - 720]Waterfowl (100 - 200 bird years) 0.2 kg/bird/yr 20 - 40 30 11 – 6Internal Loading 2/3 lake area x 0.5 mg/m 2 /d x 90 d 62 62 22 – 12Total 280 - 509With 60% surface water phosphorus reduction 195 - 287% remaining 70 - 56Predicted in-lake TP concentration 7 – 11 ug/L1Average Precipitation 1994-2001(1.2m) * Lake Surface Area (511.7 ac); Assumed precipitation concentration 10 - 20 ug/L2Assuming an area of 200 ac of direct groundwater drainage. Low range from 200 ac * 20 L/m 2 /day. High range (Q=CIA); where C = 0.05, I =221 m/yr, A = 80645 m 2 ; Assumed TP in GW at 10 - 20 ug/L3Assuming 1.5 cfs/mi 2 * watershed area (3.7 mi 2 ); through subtracting precipitation and groundwater from input volume (8.9 x 10 6 m 3 )4Assuming runoff coefficient of 0.3; used wet weather median and average TP concentrations; used percent Dissolved Phosphorus to TotalPhosphorus to calculate "Best Estimate" (40% of TP was DP)5Difference between surface water and wet weather; used dry weather median and average TP concentrations; used percent DissolvedPhosphorus to Total Phosphorus to calculate "Best Estimate" (29% of TP was DP)6Calculated from land export coefficient (0.3 - 0.5) used in DF and Ad Hoc Advisory studies and watershed land use (AHLAC and CT DEP)7Mass balance using whole lake and epilimnion volumesLake Pocotopaug Restoration Evaluation 84May 2002
Surface water TP loading can also be calculated by using a load coefficient. Thistechnique was used by the AHLAC and the range of values was tighter than the rangecalculated using actual data (as described in the previous paragraph). A load coefficientof 0.3 – 0.5, depending on land use was used, in previous investigations, predicting a TPload of 232 – 480 kg/yr.Additionally, a mass balance equation (using both whole lake and eplimnion areas and a75% retention rate) was to estimate the TP load. Mass balance results provide a TPrange of 280 – 720 kg/yr.Waterfowl contributions were based an estimated 100-200 bird/years multiplied by aphosphorus concentration of 0.2 kg/bird/yr (Brezonik, 1973; Manny et al., 1994).Waterfowl are estimated to provide 6 to 11 percent of the total phosphorus load to LakePocotopaug. Fugro (1993) estimated that waterfowl contribute 43 kg/yr (about 4% of thebudget estimated by Fugro).Internal loading was calculated based on the expected remaining sediment releasefollowing alum treatment. The 2002 in-lake data clearly indicate that internal loadingand the rate of contribution were greatly reduced by the alum treatment. Therefore, anadjusted rate of 0.5 mg/m 2 /day (typical of oxic sedments in other lakes studied by ENSRstaff) was applied to the untreated lake area for a period of 90 days (summer), resultingin an annual load of 62 kg/yr, or 12 – 22 % of the current TP budget.8.4 Tributary and Storm Drain LoadingA method for determining the phosphorus load from the watershed used in the “LandUse and Phosphorus Input to Lake Pocotopaug” by the AHLAC in 1995 was repeatedusing median 2001 stormwater data and is presented in Table 19.Additionally, the relative phosphorus load was calculated using median stormwaterconcentrations in 2001 (Table 20). Table 20 is sorted by percent relative loadcontribution. Hales, Bay, O’Neils, and Christopher Brooks contribute the bulk of the TPentering Lake Pocotopaug. However, excessive phosphorus loading is prevalentthroughout the watershed.Lake Pocotopaug Restoration Evaluation 85May 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 20 and 21:
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 30 and 31:
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
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 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
show all

Lake Pocotopaug Lake and Watershed Restoration Evaluation ...

You also want an ePaper? Increase the reach of your titles

Delete template?

Save as template?