| Report Year: 2009 |
| Lake of the Hills, Scott County |
| Summary Data Table |
| Parameter | 6/23/2009 | 7/28/2009 | 2009 | 2007 | 2006 | 2005 | 2004 | 2003 | 2002 | 2001 | 2000 |
| Lake Depth (m) | 5.6 | 5.9 | 5.8 | 5.9 | 5.7 | 6.2 | 5.8 | 6.1 | 6.2 | 6.3 | 5.9 |
| Thermocline Depth (m) | 1.9 | 3.8 | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A |
| Secchi Disk Depth (m) | 1.2 | 0.8 | 1.0 | 0.7 | 0.9 | 0.8 | 0.6 | 0.9 | 0.6 | 1.2 | 0.7 |
| Temperature(oC) | 28.2 | 24.9 | 26.6 | 25.4 | 25.1 | 27.4 | 25.6 | 24.5 | 26.3 | 26.5 | 25.2 |
| Dissolved Oxygen (mg/L) | 13.4 | 8.9 | 11.2 | 7.4 | 9.2 | 8.6 | 11.3 | 7.5 | 10.9 | 12.5 | 4.2 |
| Dissolved Oxygen Saturation (%) | 172 | 108 | 140.0 | 89.5 | 111.5 | 109.3 | 139.3 | 88.9 | 138.9 | 155.2 | 50.8 |
| Specific Conductivity (μS/cm) | 420.0 | 410.0 | 415.0 | 369.3 | 500.2 | 492.8 | 399.2 | 414.3 | 557.4 | 416.2 | 417.1 |
| Turbidity (NTU) | 3.9 | 10.0 | 6.9 | 13.2 | 4.6 | 10.5 | 14.2 | 13.0 | 17.3 | 9.5 | 13.3 |
| Chlorophyll a (μg/L) | 24.0 | 36.0 | 30.0 | 32.1 | 20.5 | 38.5 | 50.3 | 22.5 | 36.6 | 13.0 | 4.4 |
| Total Phosphorus as P (μg/L) | 47 | 63 | 55 | 59 | 47 | 50 | 81 | 68 | 77 | 51 | 114 |
| SRP as P (μg/L) | - | - | - | 1 | 1 | 1 | 1 | 1 | 1 | - | - |
| Total Nitrogen as N (mg/L) | 1.05 | 1.05 | 1.05 | 1.19 | 1.04 | 0.97 | 4.68 | 1.26 | 1.25 | 1.57 | 1.27 |
| (Phenate)Ammonia Nitrogen (NH3 + NH4+) as N (μg/L) | 16 | 16 | 16 | 51 | 82 | 92 | 92 | - | - | - | - |
| (Phenate)Ammonia Nitrogen (NH3) as N (un-ionized)(μg/L) | 2.9 | 0.9 | 1.9 | 6.1 | 6.3 | 8.7 | 12.3 | - | - | - | - |
| Nitrate + Nitrite (NO3 + NO2) as N (mg/L) | 0.24 | 0.12 | 0.14 | 0.21 | 0.12 | 0.16 | 3.49 | 0.29 | 0.43 | 0.69 | 0.23 |
| TN:TP ratio | 22 | 17 | 19 | 21 | 24 | 20 | 49 | 18 | 20 | 33 | 18 |
| pH | 8.7 | 8.9 | 8.8 | 8.6 | 8.4 | 8.4 | 8.6 | 8.5 | 8.5 | 8.4 | 7.2 |
| Alkalinity as CaCO3 (mg/L) | 160 | 147 | 154 | 137 | 174 | 177 | 148 | 110 | 145 | 150 | 150 |
| Silica as Si (mg/L) | - | - | - | - | - | 1.91 | 3.03 | 1.87 | 2.34 | - | - |
| Dissolved Organic Carbon (mg/L) | 4.92 | 3.93 | 4.43 | 4.78 | 5.44 | 7.61 | 3.92 | 7.29 | 7.00 | - | - |
| Inorganic Suspended Solids (mg/L) | 1 | 4 | 3 | 5 | 6 | 6 | 9 | 5 | 8 | 5 | 6 |
| Volatile Suspended Solids (mg/L) | 7 | 10 | 9 | 7 | 5 | 8 | 7 | 5 | 9 | 5 | 5 |
| Total Suspended Solids (mg/L) | 8 | 15 | 11 | 12 | 10 | 14 | 15 | 10 | 17 | 8 | 11 |
| Carlson Trophic State Index (Secchi)* | 57 | 63 | 60 | 65 | 62 | 64 | 67 | 62 | 67 | 58 | 65 |
| Carlson Trophic State Index (Chl a)* | 62 | 66 | 64 | 65 | 60 | 66 | 69 | 61 | 66 | 56 | 45 |
| Carlson Trophic State Index (TP)* | 60 | 64 | 62 | 63 | 60 | 60 | 68 | 65 | 67 | 61 | 73 |
| *Index values generally range between 0 and 100, with increasing values indicating more eutrophic conditions. |