| Report Year: 2009 |
| Center Lake, Dickinson County |
| Summary Data Table |
| Parameter | 6/2/2009 | 7/7/2009 | 2009 | 2007 | 2006 | 2005 | 2004 | 2003 | 2002 | 2001 | 2000 |
| Lake Depth (m) | 4.7 | 4.7 | 4.7 | 4.8 | 4.9 | 5.1 | 4.6 | 4.8 | 4.5 | 4.8 | 4.7 |
| Thermocline Depth (m) | Nil | Nil | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A |
| Secchi Disk Depth (m) | 1.6 | 1.5 | 1.6 | 1.0 | 1.0 | 1.9 | 1.6 | 2.3 | 0.8 | 2.3 | 0.9 |
| Temperature(oC) | 19.8 | 23.9 | 21.8 | 23.0 | 23.9 | 22.5 | 21.6 | 21.6 | 23.0 | 22.4 | 24.3 |
| Dissolved Oxygen (mg/L) | 9.1 | 11.4 | 10.2 | 8.7 | 11.1 | 9.4 | 10.9 | 10.9 | 9.3 | 10.2 | 9.2 |
| Dissolved Oxygen Saturation (%) | 100 | 134 | 117.0 | 100.9 | 130.7 | 107.1 | 126.1 | 124.6 | 107.6 | 120.2 | 108.9 |
| Specific Conductivity (μS/cm) | 630.0 | 660.0 | 645.0 | 598.1 | 585.5 | 595.6 | 605.4 | 552.0 | 644.7 | 562.2 | 505.3 |
| Turbidity (NTU) | 3.9 | 11.0 | 7.4 | 9.0 | 26.7 | 158.1 | 157.2 | 12.5 | 9.3 | 23.2 | 13.9 |
| Chlorophyll a (μg/L) | 6.0 | 11.0 | 8.5 | 61.3 | 66.3 | 74.8 | 21.2 | 12.5 | 29.0 | 50.0 | 48.6 |
| Total Phosphorus as P (μg/L) | 38 | 61 | 49 | 90 | 106 | 125 | 112 | 71 | 90 | 113 | 234 |
| SRP as P (μg/L) | 12 | - | 12 | 6 | 1 | 44 | 25 | 12 | 13 | - | - |
| Total Nitrogen as N (mg/L) | 1.60 | 1.54 | 1.57 | 2.15 | 2.27 | 1.79 | 1.86 | 1.97 | 2.03 | 1.98 | 2.18 |
| (Phenate)Ammonia Nitrogen (NH3 + NH4+) as N (μg/L) | 433 | 16 | 220 | 159 | 98 | 70 | 129 | - | - | - | - |
| (Phenate)Ammonia Nitrogen (NH3) as N (un-ionized)(μg/L) | 47.5 | 1.8 | 24.6 | 26.2 | 29.3 | 20.1 | 27.5 | - | - | - | - |
| Nitrate + Nitrite (NO3 + NO2) as N (mg/L) | 0.26 | 0.12 | 0.18 | 0.25 | 0.12 | 0.30 | 0.31 | 0.30 | 0.35 | 0.25 | 0.30 |
| TN:TP ratio | 42 | 25 | 34 | 25 | 22 | 17 | 19 | 28 | 23 | 18 | 10 |
| pH | 8.5 | 8.9 | 8.7 | 8.6 | 8.8 | 8.6 | 8.8 | 8.6 | 8.4 | 8.0 | 8.6 |
| Alkalinity as CaCO3 (mg/L) | 188 | 176 | 182 | 163 | 169 | 184 | 180 | 133 | 166 | 127 | 204 |
| Silica as Si (mg/L) | - | - | - | - | - | 9.72 | 10.73 | 6.20 | 6.83 | - | - |
| Dissolved Organic Carbon (mg/L) | 11.85 | 10.70 | 11.28 | 25.28 | 12.54 | 14.75 | 13.89 | 16.38 | 17.70 | - | - |
| Inorganic Suspended Solids (mg/L) | 2 | 1 | 1 | 6 | 5 | 6 | 2 | 5 | 3 | 3 | 7 |
| Volatile Suspended Solids (mg/L) | 5 | 7 | 6 | 7 | 12 | 6 | 6 | 6 | 8 | 3 | 7 |
| Total Suspended Solids (mg/L) | 7 | 7 | 7 | 10 | 16 | 11 | 7 | 12 | 12 | 7 | 14 |
| Carlson Trophic State Index (Secchi)* | 53 | 54 | 54 | 60 | 60 | 51 | 53 | 48 | 63 | 48 | 62 |
| Carlson Trophic State Index (Chl a)* | 48 | 54 | 52 | 71 | 72 | 73 | 61 | 55 | 64 | 69 | 69 |
| Carlson Trophic State Index (TP)* | 57 | 63 | 60 | 69 | 71 | 74 | 72 | 66 | 69 | 72 | 83 |
| *Index values generally range between 0 and 100, with increasing values indicating more eutrophic conditions. |