Cooks Bay (DNR ID: 27-0133-05)
Sampling Location GPS Coordinates: Surface Area: 362 acres Max. Depth: 43 ft
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Cooks Bay is located in Mound. 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 Bartlett Blvd and continue until Bay Park, which is on the right side of the road. Public boat access is available.
Lake Minnetonka is a class 2B lake protected for aquatic life and recreation. Water quality information is available beginning in 1996. MCWD staff have been monitoring the site on Cooks Bay on a bi-weekly basis from the time of ice out (April) to the time of fall mixing (mid-October) since 2006.
Not Currently 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.
| 2008 Summer Water Quality Summary |
| Parameters | Range | Mean | TSI Value | Lake Grade |
| Months | June - Sept. | May - Sept. | ||
| Secchi Depth (m) | 1.4 - 3.9 | 2.3 | 48 | B |
| Surface TP (µg/L) | 17 - 37 | 24.3 | 50 | B |
| Chlorophyll-a (µg/L) | 6 - 21 | 13.7 | 56 | B |
| Overall Score | 51 | B |
The following summary refers to Figure 3.9 (a-d).
- Secchi disk depth remained above the standard (> 1.2 m) throughout the entire season. From late April to the early June, secchi disk depth increased ranging between 2.1 m and 3.9 m. Secchi disk depth decreased from the rest of June to the end July ranging from 3.8 m to 1.6 m. From August to September, secchi disk depth fluctuated between 1.4 m and 2 m then in October, secchi disk depth increased to 2.7 m.
- Chlorophyll-a concentrations decreased from 16 µg/L to 6 µg/L from late April to late June. The remainder of the season, there was an overall increase in concentrations. Highest chlorophyll-a concentrations of the season were reached in early and late September at 21 µg/L (standard < 15 µg/L).
- Surface TP concentrations were below the standard limit for the entire season (< 40 µg/L) and fluctuated between 17 µg/L and 39 µg/L. Surface SRP were below detection limit (< 0.005 µg/L) except in late May, early September and the middle of October.
- Both bottom TP and SRP concentrations increased from late April to early September, then declined for the remainder of the season. The highest bottom TP concentration of the season was reached in middle of August (510 µg/L), where highest bottom SRP concentration occurred in early September (185 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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