Crystal Bay (DNR ID: 27-0133-10)
Sampling Location GPS Coordinates: Surface Area: 800 acres Max. Depth: 113 ft
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Crystal Bay is located near the cities of Spring Park and Orono. Head east on Minnetonka Blvd, and turn left on Co Rd 101 S. Turn right at Grays Bay Blvd and continue on Bushaway Rd. Turn left on Eastman Ln/Shady Ln, then a slight right at E Circle Dr. Next take a slight left at Lake St. E. Turn left at Ferndale Rd S and continue on Shoreline Dr. Turn right at Northshore Dr. Public lake access is available at the North Arm boat access located off of Northshore Drive (Co Rd 51) two miles west from Shoreline Drive (Co Rd 15) at Smiths Bay.
Crystal Bay on 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 Crystal Bay 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) | 2.3 - 3.8 | 2.9 | 45 | A |
| Surface TP (µg/L) | 15 - 28 | 20.4 | 48 | A |
| Chlorophyll-a (µg/L) | 3 - 7 | 4.8 | 46 | A |
| Overall Score | 46 | A |
The following summary refers to Figure 3.11 (a-d).
- Late April to early May, secchi disk depth increased from 4.2 m to 4.9 m, then decreased
to 2.5 m by early June. Secchi disk depth gradually increased from late June to late
September, then decreased from 3.8 m to 2.2 m by the middle of October
(standard > 1.4 m). - Chlorophyll-a concentrations ranged between 3 μg/L and 7 μg/L except in the middle of
May (8.5 μg/L ) and the middle of October (10 μg/L) (standard < 14 μg/L). - Surface TP concentrations gradually decreased from late April to late September, and
then increased in October. TP concentrations ranged between 15 μg/L and 31 μg/L
throughout the season (standard < 40 μg/L). Surface SRP were below detection limit
(< 0.005 μg/L) except in the middle of October (6 μg/L). - Bottom TP concentrations decreased from 75 μg/L to 47 μg/L from late April to early
May and then gradually increased from 47 μg/L to 232 μg/L the remainder of the season.
Bottom SRP concentrations gradually increased from 8 μg/L to 229 μg/L throughout the
season.
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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