| Report Year: 2009 |
| Cold Springs Lake, Cass County |
| Summary Data Table |
| Parameter | 7/14/2009 | 6/9/2009 | 2009 | 2007 | 2006 | 2005 | 2004 | 2003 | 2002 | 2001 | 2000 |
| Lake Depth (m) | 4.2 | 4.3 | 4.3 | - | - | 4.4 | 4.6 | 4.2 | 4.2 | 4.3 | 4.6 |
| Thermocline Depth (m) | 3.1 | 3.4 | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A |
| Secchi Disk Depth (m) | 1.6 | 2.3 | 1.9 | - | - | 0.7 | 0.6 | 0.7 | 0.7 | 0.5 | 0.4 |
| Temperature(oC) | 25.8 | 22.0 | 23.9 | - | - | 25.2 | 24.1 | 24.5 | 25.3 | 23.8 | 26.8 |
| Dissolved Oxygen (mg/L) | 8.6 | 8.6 | 8.6 | - | - | 10.2 | 7.8 | 10.7 | 13.3 | 9.5 | 9.0 |
| Dissolved Oxygen Saturation (%) | 105 | 98 | 101.5 | - | - | 123.2 | 93.4 | 128.1 | 162.4 | 106.0 | 112.2 |
| Specific Conductivity (μS/cm) | 240.0 | 230.0 | 235.0 | - | - | 290.1 | 322.4 | 280.3 | 263.6 | 191.7 | 237.8 |
| Turbidity (NTU) | 3.4 | 3.3 | 3.3 | - | - | 49.4 | 24.2 | 15.2 | 18.8 | 49.3 | 38.9 |
| Chlorophyll a (μg/L) | 18.0 | 6.0 | 12.0 | - | - | 37.2 | 27.2 | 24.9 | 30.6 | 94.1 | 57.3 |
| Total Phosphorus as P (μg/L) | 63 | 27 | 45 | - | - | 53 | 67 | 58 | 52 | 145 | 260 |
| SRP as P (μg/L) | - | - | - | - | - | 2 | 2 | 1 | 1 | - | - |
| Total Nitrogen as N (mg/L) | 1.28 | 0.28 | 0.70 | - | - | 0.91 | 1.65 | 1.51 | 1.00 | 2.10 | 1.63 |
| (Phenate)Ammonia Nitrogen (NH3 + NH4+) as N (μg/L) | 83 | 32 | 58 | - | - | 20 | 297 | - | - | - | - |
| (Phenate)Ammonia Nitrogen (NH3) as N (un-ionized)(μg/L) | 10.9 | 7.2 | 9.0 | - | - | 3.4 | 20.7 | - | - | - | - |
| Nitrate + Nitrite (NO3 + NO2) as N (mg/L) | 0.12 | 0.12 | 0.12 | - | - | 0.22 | 0.31 | 0.34 | 0.25 | 0.67 | 0.32 |
| TN:TP ratio | 20 | 4 | 12 | - | - | 16 | 25 | 33 | 20 | 15 | 6 |
| pH | 8.4 | 8.8 | 8.6 | - | - | 8.6 | 8.2 | 8.7 | 9.0 | 8.9 | 7.8 |
| Alkalinity as CaCO3 (mg/L) | 117 | 105 | 111 | - | - | 129 | 148 | 83 | 103 | 95 | 112 |
| Silica as Si (mg/L) | - | - | - | - | - | 4.52 | 6.54 | 6.10 | 3.62 | - | - |
| Dissolved Organic Carbon (mg/L) | 5.25 | 5.32 | 5.29 | - | - | 6.47 | 5.07 | 11.85 | 10.89 | - | - |
| Inorganic Suspended Solids (mg/L) | 7 | 1 | 4 | - | - | 6 | 9 | 6 | 7 | 11 | 9 |
| Volatile Suspended Solids (mg/L) | 8 | 3 | 6 | - | - | 9 | 9 | 15 | 10 | 38 | 17 |
| Total Suspended Solids (mg/L) | 15 | 3 | 9 | - | - | 15 | 18 | 21 | 17 | 48 | 27 |
| Carlson Trophic State Index (Secchi)* | 53 | 48 | 51 | - | - | 64 | 67 | 65 | 65 | 69 | 73 |
| Carlson Trophic State Index (Chl a)* | 59 | 48 | 55 | - | - | 66 | 63 | 62 | 64 | 75 | 70 |
| Carlson Trophic State Index (TP)* | 64 | 52 | 59 | - | - | 61 | 65 | 63 | 61 | 76 | 84 |
| *Index values generally range between 0 and 100, with increasing values indicating more eutrophic conditions. |