| Report Year: 2009 |
| Carter Lake, Pottawattamie County |
| Summary Data Table |
| Parameter | 6/9/2009 | 7/14/2009 | 2009 | 2007 | 2006 | 2005 | 2004 | 2003 | 2002 | 2001 | 2000 |
| Lake Depth (m) | 6.4 | 6.7 | 6.6 | 6.9 | 6.2 | 6.6 | 7.4 | 6.9 | 7.0 | 7.9 | 7.1 |
| 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) | 0.4 | 0.4 | 0.4 | 1.3 | 0.2 | 0.2 | 0.4 | 0.2 | 0.2 | 0.5 | 0.3 |
| Temperature(oC) | 21.2 | 25.8 | 23.5 | 26.5 | 26.3 | 24.2 | 23.8 | 25.2 | 26.2 | 24.2 | 25.8 |
| Dissolved Oxygen (mg/L) | 8.2 | 4.6 | 6.4 | 7.7 | 5.0 | 5.2 | 9.0 | 9.3 | 8.9 | 8.3 | 7.6 |
| Dissolved Oxygen Saturation (%) | 92 | 57 | 74.3 | 94.7 | 62.0 | 62.3 | 106.8 | 112.1 | 110.5 | 98.5 | 93.4 |
| Specific Conductivity (μS/cm) | 720.0 | 730.0 | 725.0 | 665.7 | 797.9 | 740.7 | 681.2 | 681.2 | 650.2 | 605.7 | 693.2 |
| Turbidity (NTU) | 26.4 | 40.1 | 33.2 | 38.1 | 93.4 | 57.5 | 51.8 | 75.7 | 60.9 | 59.7 | 56.4 |
| Chlorophyll a (μg/L) | 32.0 | 90.0 | 61.0 | 69.0 | 256.4 | 311.7 | 68.3 | 27.5 | 173.2 | 98.5 | 113.8 |
| Total Phosphorus as P (μg/L) | 119 | 181 | 150 | 132 | 197 | 243 | 170 | 230 | 213 | 186 | 200 |
| SRP as P (μg/L) | 1 | - | 1 | 1 | 2 | 2 | 2 | 2 | 4 | - | - |
| Total Nitrogen as N (mg/L) | 0.28 | 2.04 | 1.14 | 1.42 | 3.38 | 2.26 | 2.25 | 2.50 | 1.66 | 1.96 | 2.25 |
| (Phenate)Ammonia Nitrogen (NH3 + NH4+) as N (μg/L) | 16 | - | 16 | 109 | 16 | 393 | 130 | - | - | - | - |
| (Phenate)Ammonia Nitrogen (NH3) as N (un-ionized)(μg/L) | 0.7 | - | 0.7 | 10.7 | 2.0 | 59.2 | 26.6 | - | - | - | - |
| Nitrate + Nitrite (NO3 + NO2) as N (mg/L) | - | 0.12 | 0.12 | 0.12 | 0.12 | 0.14 | 0.15 | 0.12 | 0.12 | 0.19 | 0.14 |
| TN:TP ratio | 2 | 11 | 7 | 11 | 17 | 9 | 14 | 11 | 7 | 11 | 12 |
| pH | 8.4 | 8.6 | 8.5 | 8.3 | 9.0 | 8.3 | 8.5 | 8.6 | 8.6 | 8.1 | 8.0 |
| Alkalinity as CaCO3 (mg/L) | 218 | 209 | 214 | 191 | 182 | 193 | 196 | 148 | 194 | 198 | 216 |
| Silica as Si (mg/L) | - | - | - | - | - | 12.44 | 9.09 | 10.11 | 9.16 | - | - |
| Dissolved Organic Carbon (mg/L) | 7.67 | 5.90 | 6.79 | 7.19 | 11.62 | <3.6 | 6.36 | 11.38 | 10.03 | - | - |
| Inorganic Suspended Solids (mg/L) | 10 | 24 | 17 | 6 | 10 | 10 | 8 | 9 | 5 | 5 | 5 |
| Volatile Suspended Solids (mg/L) | 21 | 22 | 21 | 17 | 37 | 31 | 19 | 27 | 22 | 16 | 8 |
| Total Suspended Solids (mg/L) | 31 | 46 | 39 | 23 | 47 | 41 | 27 | 36 | 27 | 21 | 13 |
| Carlson Trophic State Index (Secchi)* | 75 | 75 | 75 | 56 | 87 | 83 | 74 | 80 | 82 | 70 | 77 |
| Carlson Trophic State Index (Chl a)* | 65 | 75 | 71 | 72 | 85 | 87 | 72 | 63 | 81 | 76 | 77 |
| Carlson Trophic State Index (TP)* | 73 | 79 | 76 | 75 | 80 | 83 | 78 | 83 | 81 | 80 | 81 |
| *Index values generally range between 0 and 100, with increasing values indicating more eutrophic conditions. |