West Upper Lake (Crane Island) (DNR ID: 27-0133-05)
Sampling Location GPS Coordinates: 44.9046N, -93.6665W Surface Area: 879 acres Max. Depth: 84 ft
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West Upper Lake is located near the city of Minnetrista. Head east on Minnetonka Blvd, and turn right on Co Rd 101 S. Turn right MN-7 and turn right at Hwy 44. Next turn right at Lake Minnetonka Regional Park and follow the path towards the public boat access.
West Upper Lake is on Lake Minnetonka which is a class 2B lake protected for aquatic life and recreation. Water quality information is available starting in 1977, but regular monitoring did not begin until 1997. MCWD staff have been monitoring the site on West Upper Lake on a bi-weekly basis from the time of ice out (April) to the time of fall mixing (mid-October) since 2006.
See Previous Reports.
Monitoring season started in late April and ended in late October. A YSI multi-probe sonde was used to measure dissolved oxygen (DO), temperature (oC), pH, and specific conductivity (µS/cm) at each meter depth from the water surface to the bottom. Additionally, water samples were collected within the first two meters of the surface with a 2-meter composite sampling tube. Samples one meter below the thermocline and one meter above the bottom were collected with a Van Doran water sampler. Surface samples were analyzed for total phosphorus (TP), soluble reactive phosphorus (SRP), total nitrogen (TN), where bottom and thermocline samples were analyzed for TP and SRP. Surface concentrations of chlorophyll-a were also analyzed and measurements of Secchi disc depth were recorded.
| 2009 Summer Water Quality Summary |
| Parameters | Range | Mean | TSI Value | Lake Grade |
| Months | June - Sept. | May - Sept. | ||
| Secchi Depth (m) | 1.8 - 2.7 | 2.4 | 47 | B |
| Surface TP (µg/L) | 21 - 25 | 22.3 | 49 | B |
| Chlorophyll-a (µg/L) | 5 - 15 | 9.3 | 53 | A |
| Overall Score | 50 | B+ |
The following summary refers to Figure 3.55 (a-d).
- Secchi disk depth increased to 4.1 m by late May, and then decreased to 2.3 m by the middle of June. From late June to early August, Secchi disk depth fluctuated between 2.4 m and 3.3 m, and then declined to 1.8 m by early September. Secchi disk depth slightly increased to 2.5 m by early October (standard > 1.4 m).
- Chlorophyll-a concentrations increased throughout late April to early August ranging from 4 μg/L to 9 μg/L. From late August to early October, chlorophyll-a ranged between 12 μg/L and 15 μg/L with concentrations decline to 8 μg/L by the end of the season
(standard < 14 μg/L). - Surface TP concentrations increased from 23 μg/L to 86 μg/L from late April to early May (standard < 40 μg/L). Then until late September, TP concentrations fluctuated between 21 μg/L and 27 μg/L. In early October, concentrations increased to 42 μg/L.
Surface SRP concentrations were below detection limit (< 0.005 μg/L) for the entire season except in early October (12 μg/L). - Both bottom TP and SRP concentrations increased throughout the entire season, except for early May.* Early May SRP concentration was greater than TP which may be due to the presence of silica (7.86 mg/L) within the sample (email correspondence; RMB, 2008).
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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