| Report Year: 2009 |
| Green Castle Lake, Marshall County |
| Summary Data Table |
| Parameter | 6/15/2009 | 7/20/2009 | 2009 | 2007 | 2006 | 2005 | 2004 | 2003 | 2002 | 2001 | 2000 |
| Lake Depth (m) | 7.1 | 7.0 | 7.1 | 7.1 | 7.1 | 7.1 | 7.4 | 7.3 | 7.4 | 7.3 | 6.1 |
| Thermocline Depth (m) | 2.2 | 3.1 | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A |
| Secchi Disk Depth (m) | 1.3 | 0.8 | 1.0 | 2.6 | 3.4 | 3.0 | 3.6 | 3.6 | 3.1 | 1.8 | 1.3 |
| Temperature(oC) | 21.7 | 22.4 | 22.0 | 26.5 | 24.4 | 24.2 | 22.2 | 24.3 | 25.9 | 23.3 | 25.8 |
| Dissolved Oxygen (mg/L) | 9.3 | 10.3 | 9.8 | 10.1 | 8.0 | 9.7 | 9.4 | 8.7 | 6.3 | 10.3 | 9.8 |
| Dissolved Oxygen Saturation (%) | 105 | 118 | 111.7 | 125.3 | 95.6 | 115.0 | 107.2 | 103.2 | 80.0 | 121.6 | 120.8 |
| Specific Conductivity (μS/cm) | 430.0 | 380.0 | 405.0 | 290.1 | 314.2 | 310.8 | 294.1 | 337.4 | 374.8 | 353.6 | 304.4 |
| Turbidity (NTU) | 4.1 | 5.5 | 4.8 | 2.5 | 2.6 | 136.4 | 10.2 | 3.0 | 9.8 | 4.3 | 10.9 |
| Chlorophyll a (μg/L) | 7.0 | 9.0 | 8.0 | 6.0 | 1.6 | 13.8 | 22.0 | 4.5 | 4.6 | 6.7 | 12.0 |
| Total Phosphorus as P (μg/L) | 38 | 48 | 43 | 26 | 20 | 36 | 25 | 34 | 24 | 48 | 47 |
| SRP as P (μg/L) | - | - | - | 1 | 2 | 2 | 2 | 4 | 1 | - | - |
| Total Nitrogen as N (mg/L) | 2.19 | 1.53 | 1.86 | 1.25 | 0.67 | 1.00 | 1.50 | 1.15 | 0.60 | 2.01 | 0.97 |
| (Phenate)Ammonia Nitrogen (NH3 + NH4+) as N (μg/L) | 16 | 25 | 16 | 52 | 47 | 53 | 16 | - | - | - | - |
| (Phenate)Ammonia Nitrogen (NH3) as N (un-ionized)(μg/L) | 0.4 | 3.9 | 2.2 | 15.1 | 15.9 | 12.0 | 4.3 | - | - | - | - |
| Nitrate + Nitrite (NO3 + NO2) as N (mg/L) | 1.61 | 0.75 | 1.18 | 0.76 | 0.20 | 0.31 | 0.68 | 0.50 | 0.15 | 1.06 | 0.15 |
| TN:TP ratio | 57 | 32 | 45 | 43 | 33 | 29 | 61 | 36 | 25 | 51 | 23 |
| pH | 8.5 | 8.6 | 8.6 | 9.1 | 8.9 | 8.7 | 9.0 | 8.5 | 8.4 | 8.2 | 8.0 |
| Alkalinity as CaCO3 (mg/L) | 188 | 163 | 176 | 120 | 125 | 136 | 106 | 95 | 137 | 150 | 176 |
| Silica as Si (mg/L) | - | - | - | - | - | 1.79 | 1.15 | 1.16 | 1.01 | - | - |
| Dissolved Organic Carbon (mg/L) | 3.28 | 3.43 | <3.6 | 3.76 | 4.39 | <3.6 | <3.6 | 9.19 | 9.59 | - | - |
| Inorganic Suspended Solids (mg/L) | 5 | 10 | 7 | 1 | 2 | 2 | 1 | 2 | 2 | 4 | 2 |
| Volatile Suspended Solids (mg/L) | 2 | 1 | 2 | 2 | 1 | 3 | 3 | 3 | 3 | 3 | 2 |
| Total Suspended Solids (mg/L) | 7 | 11 | 9 | 2 | 3 | 5 | 4 | 5 | 6 | 7 | 4 |
| Carlson Trophic State Index (Secchi)* | 57 | 63 | 60 | 46 | 42 | 44 | 41 | 42 | 44 | 52 | 57 |
| Carlson Trophic State Index (Chl a)* | 50 | 52 | 51 | 48 | 35 | 56 | 61 | 45 | 46 | 49 | 55 |
| Carlson Trophic State Index (TP)* | 57 | 60 | 58 | 51 | 47 | 56 | 50 | 55 | 50 | 60 | 60 |
| *Index values generally range between 0 and 100, with increasing values indicating more eutrophic conditions. |