| Report Year: 2009 |
| Hickory Grove Lake, Story County |
| Summary Data Table |
| Parameter | 6/15/2009 | 7/20/2009 | 2009 | 2007 | 2006 | 2005 | 2004 | 2003 | 2002 | 2001 | 2000 |
| Lake Depth (m) | 10.2 | 10.3 | 10.3 | 10.3 | 10.1 | 10.4 | 10.5 | 10.5 | 8.8 | 11.1 | 10.7 |
| Thermocline Depth (m) | 2.0 | 3.5 | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A |
| Secchi Disk Depth (m) | 1.6 | 1.0 | 1.3 | 1.3 | 2.0 | 2.9 | 1.0 | 2.7 | 3.1 | 1.9 | 1.4 |
| Temperature(oC) | 21.1 | 22.8 | 21.9 | 25.0 | 25.2 | 24.3 | 21.7 | 23.5 | 26.0 | 22.2 | 24.2 |
| Dissolved Oxygen (mg/L) | 9.4 | 12.2 | 10.8 | 10.5 | 9.8 | 10.8 | 9.8 | 10.6 | 9.2 | 9.7 | 11.8 |
| Dissolved Oxygen Saturation (%) | 105 | 141 | 123.2 | 126.5 | 118.9 | 128.8 | 111.6 | 124.9 | 112.5 | 109.9 | 140.7 |
| Specific Conductivity (μS/cm) | 410.0 | 430.0 | 420.0 | 403.0 | 512.3 | 521.8 | 360.1 | 438.2 | 470.6 | 435.9 | 407.5 |
| Turbidity (NTU) | 5.0 | 8.5 | 6.7 | 7.0 | 8.4 | 8.2 | 26.3 | 5.1 | 2.7 | 5.2 | 5.7 |
| Chlorophyll a (μg/L) | 27.0 | 12.0 | 19.5 | 17.8 | 6.9 | 15.6 | 19.8 | 17.1 | 7.2 | 15.3 | 6.6 |
| Total Phosphorus as P (μg/L) | 88 | 54 | 71 | 45 | 15 | 35 | 134 | 30 | 25 | 56 | 67 |
| SRP as P (μg/L) | - | - | - | 1 | 1 | - | 80 | 1 | 1 | - | - |
| Total Nitrogen as N (mg/L) | 5.29 | 4.94 | 5.12 | 9.08 | 6.42 | 9.04 | 7.44 | 9.09 | 9.46 | 12.24 | 3.24 |
| (Phenate)Ammonia Nitrogen (NH3 + NH4+) as N (μg/L) | 32 | 16 | 24 | 56 | 53 | 103 | 100 | - | - | - | - |
| (Phenate)Ammonia Nitrogen (NH3) as N (un-ionized)(μg/L) | 4.7 | 2.6 | 3.6 | 7.1 | 5.1 | 11.5 | 7.6 | - | - | - | - |
| Nitrate + Nitrite (NO3 + NO2) as N (mg/L) | 4.47 | 4.07 | 4.27 | 8.03 | 5.80 | 7.89 | 6.22 | 7.91 | 8.40 | 11.99 | 1.12 |
| TN:TP ratio | 60 | 91 | 76 | 198 | 506 | 292 | 96 | 331 | 408 | 265 | 51 |
| pH | 8.6 | 8.6 | 8.6 | 8.6 | 8.2 | 8.3 | 8.4 | 8.6 | 8.4 | 8.1 | 7.8 |
| Alkalinity as CaCO3 (mg/L) | 174 | 177 | 176 | 144 | 177 | 189 | 118 | 95 | 157 | 144 | 161 |
| Silica as Si (mg/L) | - | - | - | - | - | 5.43 | 7.77 | 2.47 | 1.55 | - | - |
| Dissolved Organic Carbon (mg/L) | 4.03 | 3.65 | 3.84 | 4.15 | <3.6 | <3.6 | 4.10 | 7.71 | 9.12 | - | - |
| Inorganic Suspended Solids (mg/L) | 6 | 11 | 8 | 3 | 4 | 4 | 10 | 3 | 6 | 2 | 2 |
| Volatile Suspended Solids (mg/L) | 4 | - | 4 | 4 | 3 | 4 | 5 | 4 | 4 | 2 | 4 |
| Total Suspended Solids (mg/L) | 9 | 11 | 10 | 7 | 7 | 8 | 15 | 7 | 10 | 5 | 6 |
| Carlson Trophic State Index (Secchi)* | 53 | 60 | 56 | 57 | 50 | 45 | 60 | 46 | 44 | 51 | 55 |
| Carlson Trophic State Index (Chl a)* | 63 | 55 | 60 | 59 | 50 | 58 | 60 | 58 | 50 | 57 | 49 |
| Carlson Trophic State Index (TP)* | 69 | 62 | 66 | 59 | 44 | 55 | 75 | 53 | 50 | 62 | 65 |
| *Index values generally range between 0 and 100, with increasing values indicating more eutrophic conditions. |