| Report Year: 2011 |
| Mill Creek Lake, O'Brien County |
| Summary Data Table |
| Parameter | 6/2/2011 | 7/19/2011 | 8/30/2011 | 2011 | 2010 | 2009 | 2007 | 2006 | 2005 | 2004 | 2003 | 2002 | 2001 | 2000 |
| Lake Depth (m) | 4.3 | 4.4 | 4.2 | 4.3 | 4.5 | 4.5 | - | 4.5 | 4.4 | 4.6 | 4.3 | 4.4 | 4.7 | 4.5 |
| Thermocline Depth (m) | 2.3 | 2.4 | Nil | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A |
| Secchi Disk Depth (m) | 3.3 | 1.8 | 0.6 | 1.9 | 0.8 | 1.4 | - | 4.5 | 1.1 | 1.7 | 1.6 | 0.7 | 1.9 | 0.8 |
| Temperature(oC) | 20.6 | 30.3 | 23.1 | 24.7 | 24.2 | 23.8 | - | 17.7 | 23.7 | 22.9 | 21.8 | 21.5 | 23.0 | 26.0 |
| Dissolved Oxygen (mg/L) | 12.1 | 15.3 | 7.4 | 11.6 | 7.7 | 13.0 | - | 11.8 | 9.3 | 9.5 | 8.9 | 8.9 | 6.8 | 10.1 |
| Dissolved Oxygen Saturation (%) | 135 | 203 | 87 | 141.6 | 91.4 | 153.8 | - | 123.5 | 109.4 | 112.4 | 99.2 | 97.9 | 73.4 | 125.5 |
| Specific Conductivity (μS/cm) | 480.0 | 380.0 | 450.0 | 436.7 | 416.7 | 440.0 | - | 494.7 | 496.7 | 500.4 | 496.4 | 470.4 | 476.9 | 576.1 |
| Turbidity (NTU) | 3.3 | 6.1 | 28.3 | 12.6 | 5.5 | 3.5 | - | 4.3 | 11.3 | 8.0 | 8.4 | 24.4 | 15.4 | 23.8 |
| Chlorophyll a (μg/L) | <5 | 21.0 | 46.8 | 24.0 | 22.4 | 6.7 | - | 1.5 | 26.3 | 10.2 | 13.2 | 48.6 | 22.5 | 16.2 |
| Total Phosphorus as P (μg/L) | 24.1 | 41.9 | 68.0 | 44.7 | 54.9 | 33.9 | - | 12 | 53 | 44 | 52 | 66 | 55 | - |
| SRP as P (μg/L) | <11 | <11 | <11 | - | <8 | <9 | - | <1 | <1 | <1 | <1 | <1 | - | - |
| TKN (mg/L) | 1.3 | <0.5 | 3.2 | 1 | <0.5 | - | - | - | - | - | - | - | - | - |
| Total Dissolved Solids (g/L) | 0.3 | 0.3 | 0.3 | 0.3 | - | - | - | - | - | - | - | - | - | - |
| Total Nitrogen as N (mg/L) | - | - | - | - | - | 0.9 | - | 3.14 | 1.61 | 2.10 | 2.10 | 2.16 | 2.33 | 1.25 |
| (Phenate)Ammonia Nitrogen (NH3 + NH4+) as N (μg/L) | <145 | <145 | <145 | <145 | <136 | <130 | - | 55 | <26 | 56 | - | - | - | - |
| (Phenate)Ammonia Nitrogen (NH3) as N (un-ionized)(μg/L) | <PQL | <PQL | <PQL | <PQL | <PQL | <130 | - | 4 | 3 | 8 | - | - | - | - |
| Nitrate + Nitrite (NO3 + NO2) as N (mg/L) | 2.81 | 0.72 | <0.4 | 1 | <0.5 | - | - | 2.61 | 0.93 | 1.40 | 1.26 | 0.95 | 1.61 | 0.40 |
| TN:TP ratio | - | - | - | - | - | 28 | - | 268 | 34 | 50 | 43 | 36 | 99 | - |
| pH | 8.4 | 9.0 | 8.3 | 8.6 | 8.6 | 9.0 | - | 8.4 | 8.4 | 8.6 | 8.2 | 8.4 | 8.3 | 8.2 |
| Alkalinity as CaCO3 (mg/L) | 195 | 145 | 134 | 158 | 155 | 167 | - | 176 | 188 | 180 | 140 | 159 | 129 | 167 |
| Silica as Si (mg/L) | - | - | - | - | - | - | - | - | 2.01 | 1.41 | 1.13 | 1.89 | - | - |
| Dissolved Organic Carbon (mg/L) | <7.6 | <7.6 | <7.6 | <7.6 | <6.4 | <6.2 | - | 4.49 | 5.86 | 4.15 | 7.81 | 8.91 | - | - |
| Inorganic Suspended Solids (mg/L) | <5 | 6 | <5 | <5 | <4 | <4 | - | 1 | 5 | 7 | 5 | 4 | 3 | 5 |
| Volatile Suspended Solids (mg/L) | <8 | <8 | <8 | <8 | <9 | 8 | - | 1 | 7 | 4 | 4 | 12 | 5 | 10 |
| Total Suspended Solids (mg/L) | <6 | 14 | 10 | 10 | 10 | 10 | - | 2 | 12 | 11 | 10 | 11 | 8 | 14 |
| Carlson Trophic State Index (Secchi)* | 43 | 52 | 68 | 51 | 64 | 55 | - | 38 | 59 | 52 | 53 | 64 | 51 | 63 |
| Carlson Trophic State Index (Chl a)* | 45 | 60 | 68 | 62 | 61 | 49 | - | 35 | 63 | 53 | 56 | 69 | 61 | 58 |
| Carlson Trophic State Index (TP)* | 50 | 58 | 65 | 59 | 62 | 55 | - | 40 | 61 | 59 | 61 | 64 | 62 | - |
| *Index values generally range between 0 and 100, with increasing values indicating more eutrophic conditions. |