| Report Year: 2009 |
| Lake Manawa, Pottawattamie County |
| Summary Data Table |
| Parameter | 6/9/2009 | 7/14/2009 | 2009 | 2007 | 2006 | 2005 | 2004 | 2003 | 2002 | 2001 | 2000 |
| Lake Depth (m) | 2.3 | 2.2 | 2.3 | 2.4 | 2.2 | 2.2 | 2.1 | 2.0 | 2.0 | 2.4 | 2.2 |
| 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) | 0.5 | 0.5 | 0.5 | 0.4 | 0.3 | 0.4 | 0.4 | 0.3 | 0.5 | 0.5 | 0.3 |
| Temperature(oC) | 21.3 | 27.3 | 24.3 | 26.2 | 26.7 | 25.4 | 23.8 | 26.1 | 26.6 | 24.3 | 26.0 |
| Dissolved Oxygen (mg/L) | 7.8 | 9.9 | 8.8 | 9.2 | 8.5 | 12.4 | 10.6 | 9.1 | 9.3 | 10.7 | 10.9 |
| Dissolved Oxygen Saturation (%) | 88 | 125 | 106.3 | 113.8 | 106.1 | 151.6 | 125.7 | 110.8 | 115.4 | 130.2 | 134.1 |
| Specific Conductivity (μS/cm) | 490.0 | 470.0 | 480.0 | 412.4 | 505.7 | 465.7 | 493.8 | 499.0 | 493.1 | 455.8 | 462.1 |
| Turbidity (NTU) | 15.9 | 20.3 | 18.1 | 21.6 | 25.0 | 28.4 | 86.6 | 57.3 | 25.0 | 25.8 | 40.8 |
| Chlorophyll a (μg/L) | 38.0 | 39.0 | 38.5 | 59.2 | 63.2 | 115.1 | 43.3 | 17.9 | 58.9 | 36.6 | 36.9 |
| Total Phosphorus as P (μg/L) | 59 | 121 | 90 | 107 | 105 | 111 | 102 | 140 | 99 | 89 | 182 |
| SRP as P (μg/L) | - | 1 | 1 | 1 | 1 | 1 | 2 | 3 | 2 | - | - |
| Total Nitrogen as N (mg/L) | 0.28 | 1.37 | 0.78 | 0.50 | 1.68 | 1.27 | 1.38 | 1.35 | 1.19 | 1.21 | 1.63 |
| (Phenate)Ammonia Nitrogen (NH3 + NH4+) as N (μg/L) | 16 | 16 | 16 | 16 | 39 | 16 | 16 | - | - | - | - |
| (Phenate)Ammonia Nitrogen (NH3) as N (un-ionized)(μg/L) | 2.1 | 0.9 | 1.5 | 2.4 | 5.5 | 2.2 | 1.6 | - | - | - | - |
| Nitrate + Nitrite (NO3 + NO2) as N (mg/L) | 0.18 | 0.12 | 0.12 | 0.12 | 0.13 | 0.12 | 0.12 | 0.12 | 0.12 | 0.17 | 0.12 |
| TN:TP ratio | 3 | 11 | 7 | 6 | 18 | 12 | 13 | 10 | 12 | 17 | 11 |
| pH | 8.6 | 8.8 | 8.7 | 8.6 | 8.6 | 8.8 | 8.7 | 8.6 | 8.5 | 8.2 | 8.1 |
| Alkalinity as CaCO3 (mg/L) | 198 | 188 | 193 | 174 | 195 | 181 | 188 | 136 | 188 | 179 | 182 |
| Silica as Si (mg/L) | - | - | - | - | - | 9.42 | 11.01 | 10.92 | 8.89 | - | - |
| Dissolved Organic Carbon (mg/L) | 5.43 | 4.44 | 4.94 | 4.39 | 5.45 | 3.88 | 4.83 | 8.38 | 6.92 | - | - |
| Inorganic Suspended Solids (mg/L) | 15 | 23 | 19 | 7 | 14 | 24 | 13 | 18 | 11 | 9 | 15 |
| Volatile Suspended Solids (mg/L) | 11 | 22 | 16 | 20 | 16 | 25 | 19 | 12 | 16 | 8 | 11 |
| Total Suspended Solids (mg/L) | 26 | 45 | 35 | 27 | 30 | 49 | 32 | 30 | 27 | 17 | 27 |
| Carlson Trophic State Index (Secchi)* | 72 | 70 | 71 | 72 | 77 | 75 | 75 | 76 | 72 | 70 | 79 |
| Carlson Trophic State Index (Chl a)* | 66 | 67 | 66 | 71 | 71 | 77 | 68 | 59 | 71 | 66 | 66 |
| Carlson Trophic State Index (TP)* | 63 | 73 | 69 | 72 | 71 | 72 | 71 | 75 | 70 | 69 | 79 |
| *Index values generally range between 0 and 100, with increasing values indicating more eutrophic conditions. |