| Report Year: 2009 |
| Lake Keomah, Mahaska County |
| Summary Data Table |
| Parameter | 6/16/2009 | 7/22/2009 | 2009 | 2007 | 2006 | 2005 | 2004 | 2003 | 2002 | 2001 | 2000 |
| Lake Depth (m) | 6.1 | 6.3 | 6.2 | 6.0 | 6.2 | 8.2 | 5.9 | 5.9 | 5.8 | 6.0 | 5.7 |
| Thermocline Depth (m) | Nil | 4.2 | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A |
| Secchi Disk Depth (m) | 2.9 | 3.4 | 3.1 | 1.7 | 2.6 | 1.8 | 0.6 | 1.0 | 0.8 | 1.6 | 0.7 |
| Temperature(oC) | 19.7 | 23.8 | 21.8 | 28.0 | 27.4 | 27.7 | 24.2 | 25.5 | 27.9 | 24.7 | 25.1 |
| Dissolved Oxygen (mg/L) | 5.0 | 6.7 | 5.8 | 11.6 | 11.5 | 15.0 | 14.2 | 13.2 | 11.9 | 13.6 | 7.6 |
| Dissolved Oxygen Saturation (%) | 54 | 79 | 66.5 | 147.7 | 146.3 | 191.6 | 170.3 | 162.5 | 152.1 | 164.0 | 91.7 |
| Specific Conductivity (μS/cm) | 370.0 | 320.0 | 345.0 | 282.0 | 462.2 | 360.5 | 306.8 | 291.1 | 331.1 | 314.7 | 314.6 |
| Turbidity (NTU) | 6.3 | 1.6 | 4.0 | 18.2 | 11.3 | 13.2 | 37.4 | 38.3 | 41.3 | 16.1 | 18.2 |
| Chlorophyll a (μg/L) | 4.0 | 3.0 | 3.5 | 68.2 | 16.9 | 131.6 | 76.3 | 28.1 | 66.8 | 14.4 | 12.4 |
| Total Phosphorus as P (μg/L) | 66 | 53 | 59 | 89 | 45 | 109 | 126 | 123 | 107 | 74 | 268 |
| SRP as P (μg/L) | 16 | 8 | 12 | 2 | 3 | 10 | 4 | 1 | 1 | - | - |
| Total Nitrogen as N (mg/L) | 1.58 | 1.24 | 1.41 | 2.13 | 0.95 | 1.37 | 1.79 | 1.51 | 1.26 | 2.15 | 1.69 |
| (Phenate)Ammonia Nitrogen (NH3 + NH4+) as N (μg/L) | 188 | 155 | 172 | 144 | 30 | 47 | 43 | - | - | - | - |
| (Phenate)Ammonia Nitrogen (NH3) as N (un-ionized)(μg/L) | 13.5 | 11.8 | 12.7 | 43.0 | 2.5 | 9.5 | 14.0 | - | - | - | - |
| Nitrate + Nitrite (NO3 + NO2) as N (mg/L) | 0.83 | 0.38 | 0.61 | 0.46 | 0.12 | 0.17 | 0.28 | 0.15 | 0.16 | 0.90 | 0.34 |
| TN:TP ratio | 24 | 24 | 24 | 24 | 28 | 20 | 15 | 14 | 16 | 41 | 6 |
| pH | 8.3 | 8.2 | 8.3 | 9.0 | 8.4 | 9.0 | 9.3 | 9.1 | 9.2 | 8.5 | 7.7 |
| Alkalinity as CaCO3 (mg/L) | 133 | 120 | 127 | 97 | 146 | 114 | 102 | 73 | 92 | 106 | 155 |
| Silica as Si (mg/L) | - | - | - | - | - | 5.25 | 4.54 | 4.72 | 5.83 | - | - |
| Dissolved Organic Carbon (mg/L) | 5.25 | 4.90 | 5.08 | 7.31 | 5.81 | 5.57 | 6.83 | 12.21 | 11.64 | - | - |
| Inorganic Suspended Solids (mg/L) | 1 | 2 | 2 | 3 | 3 | 3 | 5 | 4 | 6 | 3 | 6 |
| Volatile Suspended Solids (mg/L) | 1 | 2 | 1 | 5 | 4 | 5 | 18 | 15 | 7 | 5 | 5 |
| Total Suspended Solids (mg/L) | 2 | 4 | 3 | 9 | 7 | 9 | 23 | 19 | 17 | 8 | 11 |
| Carlson Trophic State Index (Secchi)* | 45 | 43 | 44 | 52 | 46 | 52 | 67 | 60 | 64 | 53 | 65 |
| Carlson Trophic State Index (Chl a)* | 44 | 41 | 43 | 72 | 58 | 78 | 73 | 63 | 72 | 57 | 55 |
| Carlson Trophic State Index (TP)* | 64 | 61 | 63 | 69 | 59 | 72 | 74 | 74 | 71 | 66 | 85 |
| *Index values generally range between 0 and 100, with increasing values indicating more eutrophic conditions. |