Oak Lake is a prairie pothole formed approximately 14,000 years ago following the recession of glacial ice sheets. Major attributes of the Oak Lake landscape, drainage basin and lake basin are listed in the tables below. Lake monitoring is conducted by field station staff biweekly during the ice-free months (April to October). Monitoring data for the lake basin are available upon request from the Field Station Director.
Region, Drainage and Basin
| EPA Level III Ecoregion | Northern Glaciated Plains |
|---|
| EPA Level IV Ecoregion | Prairie Coteau |
| Drainage System | Minnesota-Mississippi |
| Drainage Area | 1,682 ha |
| Drainage Count | 99 |
| Drainage Density | 1.9 streams km per km2 |
| Basin Area | 163 ha |
| Basin Perimeter | 9.8 km |
| Basin Volume | 1.8 x 106 m3 |
| Average Depth | 1.1 m |
| Maximum Depth | 2.0 m |
| Basin Length | 3,081 m |
| Basin Width | 988 m |
| Shoreline Development | 2.17 |
| % Basin < 1.5 m Deep | 73% |
Average Growing Season Water Quality Characteristics (1994-Present)
| Attribute | Summer Averages | Summer Ranges |
|---|
| Trophic Status | Hypereutrophic | -- |
| Carlson Trophic State Index (Chl) | 60.1 | 11-79 |
| Secchi Depth | 47 cm | 5 - 200 |
| Water Temperature | 18.4°C | 1.0 – 30.0 |
| Dissolved Oxygen | 9.6 mg/L | 2.5 – 17.2 |
| pH (Median and Range) | 8.48 | 6.56 – 9.40 |
| Specific Conductance | 496 uS/cm | 207 - 778 |
| Total Dissolved Solids | 400 mg/L | 139 - 2427 |
| Fecal Coliform Levels | % > 200/100ml = 3.1% | Value Range <10 - 180 |
