Lake Nokomis (DNR ID: 27-0019-00)
Sampling Location - GPS Coordinates: Surface Area: 204 acres Max. Depth: 33 ft
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Lake Nokomis is located in the city of Minneapolis. Head east on Minnetonka Blvd and turn left at McGinty Rd W. Turn right to merge onto I-494 S. Next take exit 2B for State Hwy 77 N and merge onto MN-77 N. Turn right at E. Nokomis Pkwy and heads toward the lake.
Lake Nokomis is a shallow, polymictic lake that mixes multiple times during the growing season. Mixing potential increases when higher than normal wind speeds occur along the fetch of a lake. Mixing events have been hypothesized to cause the blooms of cyanobacteria, Oscillatoria agardhii, which makes the water appear reddish-brown (MPRB, 2006). Water quality data is available from 1994. Currently, Minneapolis Park and Recreation Board (MPRB) staff monitors the lake on a bi-weekly basis and send MCWD the raw data each fall.
Lake Nokomis, known as Lake Amelia, was acquired by MPRB in 1907. Nokomis resembled a wetland which included areas of open water and peat bog. Theodore Wirth (noted superintendent of MPRB) developed a plan to reduce surface water of Lake Nokomis by 100 acres and then add 100 acres of adjacent parkland. Dredging began in 1914 and nearly 2.5 million cubic yards of material was used to create beaches, shoreline and parkways around the lake. In 1934 and 1939, the newly created shoreline and parkways along Lake Nokomis had to be restored due to the fill settling. Residential development around the lake soon flourished (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) | 0.7 - 1.6 |
1.0 |
60 |
D |
| Surface TP (µg/L) | 32 - 58 |
43.9 |
59 |
C |
| Chlorophyll-a (µg/L) | 7.5 - 19.8 |
12.4 |
55 |
B |
| Overall Score | 58 |
C |
The following summary refers to Figure 2.19 (a-d).
- Secchi disk depth increased from 1.0 m to 1.6 m from late April to late June. The rest of the season secchi disk depth fluctuated between 0.65 m and 1.1 m (standard > 1.2 m).
- In general, chlorophyll-a concentrations increased from late April to October with concentrations ranging between 7.5 µg/L to 35.4 µg/L (standard < 15 µg/L).
- Surface TP concentrations ranged between 32 µg/L and 58 µg/L (standard < 40 µg/L). Surface SRP concentrations ranged between less than 0.005 µg/L and 8 µg/L.
- Bottom TP concentrations increased throughout the season peaking in early August at 173 µg/L. Bottom SRP concentrations were less than 5 µg/L for majority of the season except in early June (14 µg/L) and early August (26 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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