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.
Currently not available.
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. Water samples were collected at one meter below the water surface and one meter from the bottom. Surface and bottom sample parameters analyzed included total phosphorus (TP), total dissolved phosphorus (TDP), soluble reactive phosphorus (SRP), total nitrogen (TN), total dissolved nitrogen (TDN), nitrate/nitrite (NO3/NO2) and ammonia (NH4). Surface concentrations of chlorophyll-a were also analyzed and measurements of Secchi disc depth were recorded. An additional TP sample was taken one meter below the thermocline mixing zone once stratification developed.
| 2008 Summer Water Quality Summary |
| Parameters | Range | Mean | TSI Value | Lake Grade |
| Months | June - Sept. | May - Sept. | ||
| Secchi Depth (m) | 1.9 - 4.6 | 2.6 | 46 | B |
| Surface TP (µg/L) | 13 - 131 | 33.0 | 55 | B |
| Chlorophyll-a (µg/L) | 4 - 16 | 9.3 | 53 | A |
| Overall Score | 51 | B+ |
The following summary refers to Figure 3.55 (a-d).
- Secchi disk depth peaked at 4.3 m by late June, and then fluctuated between 1.9 m and 2.5 m for the remainder of the season (standard > 1.2 m).
- No chlorophyll-a sample was collected in late April. Chlorophyll-a concentrations ranged from 12 µg/L to 16 µg/L throughout May and from September to October. During the middle of the season concentration ranged between 4 µg/L and 8 µg/L (standard < 15 µg/L).
- Surface TP concentrations were below the standard limit for the entire season (< 40 µg/L) except for late July. Concentrations fluctuated between 13 µg/L and 28 µg/L. Surface SRP concentrations were below detection limit (< 0.005 µg/L) for the entire season. *Late July surface and bottom samples may have been mislabeled which may explain the change in both TP concentrations.
- Both bottom TP and SRP concentrations increased throughout the entire season, except for late July* Early September SRP concentration was greater than TP which may be due to silica interference within the SRP sample. Further research is needed to confirm interference (email correspondence; RMB, 2008).*See above explanation for change in bottom TP concentration.
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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