| Report Year: 2009 |
| Green Belt Lake, Black Hawk County |
| Summary Data Table |
| Parameter | 7/29/2009 | 6/24/2009 | 2009 | 2007 | 2006 | 2005 | 2004 | 2003 | 2002 | 2001 | 2000 |
| Lake Depth (m) | 5.8 | 6.0 | 5.9 | 5.6 | 4.8 | 5.3 | 5.2 | 4.8 | 4.8 | 5.4 | 5.4 |
| Thermocline Depth (m) | 3.5 | 1.6 | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A |
| Secchi Disk Depth (m) | 2.7 | 2.5 | 2.6 | 1.8 | 2.4 | 1.2 | 1.1 | 1.2 | 1.0 | 1.9 | 1.1 |
| Temperature(oC) | 24.9 | 25.9 | 25.4 | 26.0 | 26.1 | 26.7 | 24.7 | 24.6 | 25.8 | 24.9 | 24.8 |
| Dissolved Oxygen (mg/L) | 7.9 | 9.4 | 8.6 | 9.1 | 9.3 | 10.5 | 10.6 | 12.9 | 9.3 | 7.2 | 10.4 |
| Dissolved Oxygen Saturation (%) | 95 | 115 | 105.1 | 112.0 | 114.5 | 131.6 | 127.3 | 155.6 | 113.6 | 93.6 | 125.7 |
| Specific Conductivity (μS/cm) | 540.0 | 500.0 | 520.0 | 750.1 | 728.2 | 687.4 | 750.0 | 651.0 | 679.0 | 499.7 | 613.5 |
| Turbidity (NTU) | -1.1 | 1.1 | 0.0 | 3.3 | 131.5 | 17.8 | 7.7 | 8.1 | 4.6 | 6.7 | 4.4 |
| Chlorophyll a (μg/L) | 3.0 | 3.0 | 3.0 | 7.0 | 8.8 | 37.0 | 22.3 | 20.0 | 14.8 | 11.5 | 10.0 |
| Total Phosphorus as P (μg/L) | 24 | 26 | 25 | 21 | 24 | 36 | 38 | 38 | 40 | 22 | 75 |
| SRP as P (μg/L) | - | - | - | 1 | - | - | 2 | 1 | 1 | - | - |
| Total Nitrogen as N (mg/L) | 0.50 | 0.48 | 0.49 | 0.61 | 0.74 | 0.87 | 0.66 | 0.96 | 0.88 | 0.70 | 0.78 |
| (Phenate)Ammonia Nitrogen (NH3 + NH4+) as N (μg/L) | 17 | 16 | 16 | 16 | 16 | 94 | 16 | - | - | - | - |
| (Phenate)Ammonia Nitrogen (NH3) as N (un-ionized)(μg/L) | 2.1 | 0.5 | 1.3 | 0.7 | 1.3 | 8.6 | 2.2 | - | - | - | - |
| Nitrate + Nitrite (NO3 + NO2) as N (mg/L) | 0.12 | - | 0.12 | 0.12 | 0.12 | 0.12 | 0.12 | 0.12 | 0.12 | 0.36 | 0.12 |
| TN:TP ratio | 21 | 18 | 20 | 29 | 32 | 25 | 17 | 26 | 23 | 50 | 11 |
| pH | 8.4 | 8.7 | 8.5 | 8.4 | 8.2 | 8.4 | 8.6 | 8.4 | 8.2 | 8.3 | 7.4 |
| Alkalinity as CaCO3 (mg/L) | 120 | 117 | 119 | 121 | 107 | 102 | 103 | 70 | 97 | 99 | 113 |
| Silica as Si (mg/L) | - | - | - | - | - | 5.01 | 4.45 | 4.09 | 3.72 | - | - |
| Dissolved Organic Carbon (mg/L) | 3.90 | 3.81 | 3.86 | 8.40 | 5.66 | 7.15 | 6.19 | 9.49 | 8.20 | - | - |
| Inorganic Suspended Solids (mg/L) | 1 | 2 | 2 | 2 | 2 | 1 | 1 | 2 | 3 | 2 | 2 |
| Volatile Suspended Solids (mg/L) | 2 | 1 | 2 | 2 | 3 | 8 | 8 | 7 | 7 | 6 | 4 |
| Total Suspended Solids (mg/L) | 4 | 3 | 3 | 4 | 5 | 7 | 10 | 7 | 8 | 6 | 6 |
| Carlson Trophic State Index (Secchi)* | 46 | 47 | 46 | 51 | 47 | 58 | 59 | 58 | 60 | 51 | 58 |
| Carlson Trophic State Index (Chl a)* | 41 | 41 | 41 | 50 | 52 | 66 | 61 | 60 | 57 | 55 | 53 |
| Carlson Trophic State Index (TP)* | 50 | 51 | 51 | 48 | 50 | 56 | 57 | 56 | 57 | 49 | 66 |
| *Index values generally range between 0 and 100, with increasing values indicating more eutrophic conditions. |