Lake Calhoun (DNR ID: 27-0031-00)
Sampling Location - GPS Coordinates: Surface Area: 421 acres Max. Depth: 90 ft
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Lake Calhoun is located in the city of Minneapolis. Turn right at 17th Ave N/Hopkins Cross Rd and continue to follow on 17th Ave N/Hopkins Cross Rd. Turn left at MN-7. Continue to follow on W Lake St/Minnetonka Blvd and stay on W Lake St. Turn right at W. Calhoun Pkwy towards the lake.
Lake Calhoun is a deep dimictic, glacial kettle lake the generally remains stratified until late October. Lake Calhoun is the largest of the Minneapolis Chain of Lakes. It receives water from the upstream lake, Lake of the Isles, and discharges into Lake Harriet. Water quality data is available back to 1979. Currently, Minneapolis Park and Recreation Board (MPRB) staff monitor the lake on a bi-weekly basis and send MCWD the raw data each fall.
Previously known as Lake of the Loons, Lake Calhoun was renamed for John Caldwell Calhoun. While John Calhoun was Secretary of War for President Monroe, he created a military post at Fort Snelling. Similar to the other Minneapolis Chain of Lakes, Lake Calhoun was dredged and about 35 acres of the surrounding wetland areas were filled in the early part of the 1900s. Between 1911 and 1924, about 1.5 million cubic yards of soil were placed on the lake’s shoreline (MPRB, 2006).
Monitoring season started in early May and ended in late October by MPRB. Hydrolab mini-sonde 5 multi-probe measured dissolved oxygen (DO), temperature (oC), pH, and specific conductivity (µS/cm) at each meter depth from the water surface to the bottom. Surface water samples were a composite of the first two meters below the surface while bottom water samples were collected one meter from the bottom. Additional discrete samples were collected throughout the thermocline mixing zone once stratification developed. Surface sample parameters analyzed are extensive, MCWD is concerned with total phosphorus (TP), total nitrogen (TN), and soluble reactive phosphorus (SRP). Surface concentrations of chlorophyll-a were also analyzed and measurements of Secchi disc depth were recorded. Thermocline and bottom samples were analyzed for TP and SRP.
| 2008 Summer Water Quality Summary |
| Parameters | Range | Mean | TSI Value | Lake Grade |
| Months | June - Sept. | May - Sept. | ||
| Secchi Depth (m) | 1.1 - 4.1 |
2.9 |
45 |
A |
| Surface TP (µg/L) | 14 - 21 |
16.3 |
44 |
A |
| Chlorophyll-a (µg/L) | 1.3 - 4.1 |
3.2 |
42 |
A |
| Overall Score | 44 |
A |
The following summary refers to Figure 2.11 (a-d).
- Secchi disk depth increased from 3.2 m to 7.6 m from late April to late May and then decreased to 1.1 m by early August. The rest of the season, secchi disk depth ranged between 1.9 m and 3.4 m (standard > 1.2 m).
- Chlorophyll-a concentrations fluctuated between 1.3 µg/L and 4.1 µg/L from late April to late June. Then from August to October, concentrations ranged between 2.98 µg/L and 3.9 µg/L (standard < 15 µg/L).
- Surface TP concentrations ranged between 14 µg/L and 21 µg/L for the season (standard < 40 µg/L). Surface SRP concentrations ranged between less than 0.005 µg/L and 8 µg/L.
Lake Grades and Historical Monitoring Summaries
When available, previous reports are linked to applicable year. Additional lake data previous to 2007 may be available in the applicable year's hydrodata report. If you have additional questions or you are looking for specific information please contact MCWD's Water Quality Staff.
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