| Report Year: 2009 |
| Casey Lake (Hickory Hills Lake), Tama County |
| Summary Data Table |
| Parameter | 6/23/2009 | 7/28/2009 | 2009 | 2007 | 2006 | 2005 | 2004 | 2003 | 2002 | 2001 | 2000 |
| Lake Depth (m) | 6.3 | 6.2 | 6.3 | - | - | 6.1 | 6.3 | 5.9 | 6.0 | 5.9 | 6.2 |
| Thermocline Depth (m) | 1.5 | 2.3 | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A |
| Secchi Disk Depth (m) | 1.7 | 2.3 | 2.0 | - | - | 0.5 | 1.6 | 1.8 | 1.4 | 1.6 | 0.5 |
| Temperature(oC) | 27.4 | 26.2 | 26.8 | - | - | 28.4 | 24.3 | 24.6 | 26.2 | 23.9 | 23.9 |
| Dissolved Oxygen (mg/L) | 14.5 | 6.6 | 10.6 | - | - | 13.5 | 12.4 | 13.3 | 11.8 | 8.6 | 8.6 |
| Dissolved Oxygen Saturation (%) | 183 | 82 | 132.5 | - | - | 174.4 | 149.7 | 163.8 | 147.5 | 110.0 | 102.0 |
| Specific Conductivity (μS/cm) | 300.0 | 320.0 | 310.0 | - | - | 284.9 | 406.2 | 316.2 | 361.8 | 252.7 | 304.2 |
| Turbidity (NTU) | 6.6 | 0.9 | 3.8 | - | - | 26.9 | 7.5 | 24.2 | 30.7 | 38.8 | 260.0 |
| Chlorophyll a (μg/L) | 12.0 | 14.0 | 13.0 | - | - | 210.7 | 50.2 | 25.6 | 38.5 | 14.1 | 11.4 |
| Total Phosphorus as P (μg/L) | 39 | 73 | 56 | - | - | 129 | 107 | 82 | 264 | 125 | 175 |
| SRP as P (μg/L) | - | 2 | 2 | - | - | - | 70 | 9 | 2 | - | - |
| Total Nitrogen as N (mg/L) | 0.75 | 1.68 | 1.22 | - | - | 1.75 | 1.76 | 1.29 | 1.59 | 1.91 | 1.97 |
| (Phenate)Ammonia Nitrogen (NH3 + NH4+) as N (μg/L) | 16 | 258 | 131 | - | - | 20 | 124 | - | - | - | - |
| (Phenate)Ammonia Nitrogen (NH3) as N (un-ionized)(μg/L) | 1.5 | 23.0 | 12.3 | - | - | 8.4 | 22.7 | - | - | - | - |
| Nitrate + Nitrite (NO3 + NO2) as N (mg/L) | 0.12 | 0.12 | 0.12 | - | - | 0.12 | 0.87 | 0.19 | 0.55 | 0.53 | 0.25 |
| TN:TP ratio | 19 | 23 | 21 | - | - | 13 | 22 | 18 | 12 | 44 | 11 |
| pH | 9.2 | 8.2 | 8.7 | - | - | 9.4 | 8.9 | 9.0 | 9.2 | 8.5 | 7.7 |
| Alkalinity as CaCO3 (mg/L) | 131 | 183 | 157 | - | - | 111 | 123 | 95 | 119 | 119 | 130 |
| Silica as Si (mg/L) | - | - | - | - | - | 5.82 | 4.03 | 2.58 | 3.69 | - | - |
| Dissolved Organic Carbon (mg/L) | 5.09 | 6.27 | 5.68 | - | - | 7.42 | 5.42 | 10.42 | 9.18 | - | - |
| Inorganic Suspended Solids (mg/L) | 1 | 2 | 2 | - | - | 4 | 4 | 2 | 6 | 2 | 2 |
| Volatile Suspended Solids (mg/L) | 3 | 4 | 4 | - | - | 7 | 6 | 7 | 10 | 3 | 7 |
| Total Suspended Solids (mg/L) | 5 | 6 | 5 | - | - | 7 | 10 | 8 | 11 | 6 | 6 |
| Carlson Trophic State Index (Secchi)* | 53 | 48 | 50 | - | - | 72 | 54 | 51 | 55 | 53 | 71 |
| Carlson Trophic State Index (Chl a)* | 55 | 56 | 56 | - | - | 83 | 69 | 62 | 66 | 57 | 55 |
| Carlson Trophic State Index (TP)* | 57 | 66 | 62 | - | - | 74 | 72 | 68 | 85 | 74 | 79 |
| *Index values generally range between 0 and 100, with increasing values indicating more eutrophic conditions. |