| Report Year: 2011 |
| Coralville Reservoir, Johnson County |
| Summary Data Table |
| Parameter | 6/21/2011 | 8/9/2011 | 9/19/2011 | 2011 | 2010 | 2009 | 2007 | 2006 | 2005 | 2004 | 2003 | 2002 | 2001 | 2000 |
| Lake Depth (m) | 12.6 | 9.7 | 10.2 | 10.8 | 9.8 | 10.5 | 10.7 | 9.6 | 9.6 | 14.3 | 9.7 | 9.2 | 10.5 | 10.5 |
| Thermocline Depth (m) | Nil | Nil | Nil | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A |
| Secchi Disk Depth (m) | 0.7 | 0.5 | 0.4 | 0.5 | 0.6 | 0.4 | 0.5 | 0.7 | 0.8 | 0.8 | 0.7 | 0.8 | 0.8 | 0.8 |
| Temperature(oC) | 22.0 | 29.4 | 20.5 | 24.0 | 23.8 | 24.9 | 25.9 | 26.1 | 26.8 | 23.2 | 24.4 | 26.0 | 24.3 | 25.2 |
| Dissolved Oxygen (mg/L) | 8.3 | 5.9 | 7.3 | 7.1 | 5.8 | 6.1 | 7.3 | 9.4 | 6.9 | 6.6 | 6.8 | 8.5 | 8.5 | 1.6 |
| Dissolved Oxygen Saturation (%) | 94 | 77 | 81 | 84.2 | 68.6 | 74.0 | 90.2 | 115.2 | 86.5 | 77.4 | 80.9 | 106.9 | 99.1 | 19.9 |
| Specific Conductivity (μS/cm) | 500.0 | 530.0 | 480.0 | 503.3 | 490.0 | 540.0 | 529.0 | 529.2 | 617.9 | 530.1 | 599.1 | 636.1 | 582.1 | 535.7 |
| Turbidity (NTU) | 28.4 | 28.9 | 39.2 | 32.2 | 22.3 | 29.3 | 23.0 | 8.9 | 81.5 | 57.3 | 74.3 | 37.6 | 34.9 | 31.6 |
| Chlorophyll a (μg/L) | 20.5 | 8.0 | 11.6 | 13.4 | 5.4 | 9.7 | 26.4 | 40.0 | 35.0 | 15.1 | 17.2 | 17.1 | 4.9 | 7.4 |
| Total Phosphorus as P (μg/L) | 135.2 | 206.9 | 162.4 | 168.1 | 163.4 | 195.0 | 188 | 137 | 223 | 203 | 165 | 200 | 280 | - |
| SRP as P (μg/L) | 79.6 | 151.9 | 103.9 | 103.9 | 104.7 | 139.5 | 19.8 | 47.1 | 121.8 | 167.8 | 143.7 | 134.7 | - | - |
| TKN (mg/L) | 0.8 | 0.8 | <0.5 | 1 | 2 | - | - | - | - | - | - | - | - | - |
| Total Dissolved Solids (g/L) | 0.3 | 0.4 | 0.3 | 0.3 | - | - | - | - | - | - | - | - | - | - |
| Total Nitrogen as N (mg/L) | - | - | - | - | - | 5.2 | 7.16 | 6.37 | 7.57 | 7.72 | 7.32 | 6.08 | 11.77 | 6.29 |
| (Phenate)Ammonia Nitrogen (NH3 + NH4+) as N (μg/L) | <145 | 213.71 | <145 | <145 | 176 | <130 | 51 | 48 | 190 | 181 | - | - | - | - |
| (Phenate)Ammonia Nitrogen (NH3) as N (un-ionized)(μg/L) | <PQL | 25 | <PQL | <PQL | <PQL | <130 | 5 | 7 | 22 | 15 | - | - | - | - |
| Nitrate + Nitrite (NO3 + NO2) as N (mg/L) | 10.37 | 3.73 | 0.81 | 5 | 4 | - | 6.29 | 5.20 | 7.29 | 6.36 | 6.68 | 5.28 | 10.43 | 5.03 |
| TN:TP ratio | - | - | - | - | - | 27 | 37 | 47 | 34 | 42 | 40 | 31 | 45 | - |
| pH | 8.1 | 8.2 | 8.0 | 8.1 | 8.2 | 8.1 | 8.4 | 8.5 | 8.3 | 8.2 | 8.3 | 8.4 | 8.0 | 7.2 |
| Alkalinity as CaCO3 (mg/L) | 190 | 236 | 153 | 193 | 205 | 203 | 194 | 194 | 236 | 203 | 166 | 182 | 197 | 193 |
| Silica as Si (mg/L) | - | - | - | - | - | - | - | - | 9.00 | 8.69 | 7.81 | 8.16 | - | - |
| Dissolved Organic Carbon (mg/L) | <7.6 | <7.6 | <7.6 | <7.6 | <6.4 | <6.2 | 3.85 | 3.75 | 4.17 | 3.71 | 6.64 | 6.99 | - | - |
| Inorganic Suspended Solids (mg/L) | 7 | 16 | 17 | 13 | 10 | 21 | 11 | 7 | 21 | 12 | 25 | 21 | 20 | 14 |
| Volatile Suspended Solids (mg/L) | <8 | <8 | <8 | <8 | <9 | <8 | 5 | 5 | 6 | 4 | 6 | 4 | 5 | 4 |
| Total Suspended Solids (mg/L) | 11 | 19 | 21 | 17 | 12 | 27 | 15 | 13 | 27 | 16 | 31 | 25 | 25 | 18 |
| Carlson Trophic State Index (Secchi)* | 66 | 71 | 72 | 69 | 67 | 73 | 69 | 65 | 64 | 64 | 66 | 64 | 63 | 63 |
| Carlson Trophic State Index (Chl a)* | 60 | 51 | 55 | 56 | 47 | 53 | 63 | 67 | 65 | 57 | 59 | 58 | 46 | 50 |
| Carlson Trophic State Index (TP)* | 75 | 81 | 78 | 78 | 78 | 80 | 80 | 75 | 82 | 81 | 78 | 81 | 85 | - |
| *Index values generally range between 0 and 100, with increasing values indicating more eutrophic conditions. |