| Report Year: 2009 |
| Pierce Creek Lake, Page County |
| Summary Data Table |
| Parameter | 6/9/2009 | 7/14/2009 | 2009 | 2007 | 2006 | 2005 | 2004 | 2003 | 2002 | 2001 | 2000 |
| Lake Depth (m) | 2.8 | 2.9 | 2.9 | - | - | 3.1 | 3.4 | 3.1 | 3.4 | 3.8 | 3.6 |
| Thermocline Depth (m) | Nil | 2.2 | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A |
| Secchi Disk Depth (m) | 0.4 | 0.6 | 0.5 | - | - | 0.4 | 0.2 | 0.3 | 0.5 | 0.4 | 0.5 |
| Temperature(oC) | 21.0 | 25.9 | 23.5 | - | - | 24.2 | 22.2 | 25.7 | 25.2 | 23.0 | 26.0 |
| Dissolved Oxygen (mg/L) | 6.4 | 8.8 | 7.6 | - | - | 8.8 | 9.3 | 8.1 | 8.1 | 7.7 | 9.0 |
| Dissolved Oxygen Saturation (%) | 72 | 109 | 90.3 | - | - | 104.7 | 107.5 | 96.4 | 97.7 | 91.7 | 111.1 |
| Specific Conductivity (μS/cm) | 310.0 | 310.0 | 310.0 | - | - | 335.5 | 307.3 | 333.6 | 313.2 | 320.4 | 329.8 |
| Turbidity (NTU) | 42.9 | 20.7 | 31.8 | - | - | 141.1 | 265.5 | 48.8 | 38.6 | 59.9 | 31.7 |
| Chlorophyll a (μg/L) | 8.0 | 65.0 | 36.5 | - | - | 63.8 | 42.1 | 24.2 | 127.2 | 42.2 | 15.6 |
| Total Phosphorus as P (μg/L) | 109 | 146 | 127 | - | - | 149 | 245 | 133 | 108 | 159 | 202 |
| SRP as P (μg/L) | 27 | 3 | 15 | - | - | 26 | 69 | 30 | 20 | - | - |
| Total Nitrogen as N (mg/L) | 0.55 | 1.39 | 0.97 | - | - | 1.70 | 3.37 | 1.60 | 1.19 | 2.86 | 1.55 |
| (Phenate)Ammonia Nitrogen (NH3 + NH4+) as N (μg/L) | 572 | 16 | 291 | - | - | 61 | 113 | - | - | - | - |
| (Phenate)Ammonia Nitrogen (NH3) as N (un-ionized)(μg/L) | 23.3 | 2.5 | 12.9 | - | - | 6.5 | 6.0 | - | - | - | - |
| Nitrate + Nitrite (NO3 + NO2) as N (mg/L) | 0.52 | 0.12 | 0.29 | - | - | 0.82 | 2.05 | 0.46 | 0.34 | 2.24 | 0.14 |
| TN:TP ratio | 5 | 10 | 7 | - | - | 12 | 20 | 14 | 17 | 18 | 9 |
| pH | 8.0 | 8.8 | 8.4 | - | - | 8.3 | 8.3 | 8.3 | 8.2 | 7.9 | 7.6 |
| Alkalinity as CaCO3 (mg/L) | 147 | 145 | 146 | - | - | 152 | 134 | 108 | 141 | 141 | 148 |
| Silica as Si (mg/L) | - | - | - | - | - | 6.73 | 19.20 | 4.40 | 3.26 | - | - |
| Dissolved Organic Carbon (mg/L) | 5.56 | 4.62 | 5.09 | - | - | <3.6 | 4.84 | 8.34 | 8.04 | - | - |
| Inorganic Suspended Solids (mg/L) | 21 | 31 | 26 | - | - | 33 | 107 | 26 | 20 | 31 | 22 |
| Volatile Suspended Solids (mg/L) | 10 | 13 | 11 | - | - | 13 | 24 | 8 | 7 | 7 | 4 |
| Total Suspended Solids (mg/L) | 31 | 44 | 38 | - | - | 46 | 131 | 34 | 26 | 38 | 26 |
| Carlson Trophic State Index (Secchi)* | 75 | 69 | 72 | - | - | 72 | 85 | 76 | 70 | 73 | 71 |
| Carlson Trophic State Index (Chl a)* | 51 | 72 | 66 | - | - | 71 | 67 | 62 | 78 | 67 | 58 |
| Carlson Trophic State Index (TP)* | 72 | 76 | 74 | - | - | 76 | 83 | 75 | 72 | 77 | 81 |
| *Index values generally range between 0 and 100, with increasing values indicating more eutrophic conditions. |