Harrisons Bay (DNR ID: 27-0133-14)
Sampling Location GPS Coordinates: Surface Area: 211 acres Max. Depth: 46 ft
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Harrisons Bay is located near the city of Mound. Head east on Minnetonka Blvd, and turn right on Co Rd 101 S. Turn right MN-7 and turn right on Oak St which merges into Smithtown Rd. Continue onto Manitou Rd/Shadywood Rd and take a slight left to stay on Manitou Rd/Shadywood Rd. Next turn left at Shoreline Dr. Public boat launch is on the left.
Lake Minnetonka is a class 2B lake protected for aquatic life and recreation. Water quality information is available beginning in 1997. MCWD staff have been monitoring the site on Harrisons 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 above the bottom were collected with a Van Doran water sampler. Surface sample were analyzed for total phosphorus (TP), soluble reactive phosphorus (SRP), total nitrogen (TN), where the bottom 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) | 0.4 - 1.5 | 0.8 | 63 | D |
| Surface TP (µg/L) | 46 - 62 | 55.2 | 62 | C |
| Chlorophyll-a (µg/L) | 14 - 89 | 41.7 | 67 | C |
| Overall Score | 64 | C- |
The following summary refers to Figure 3.19 (a-d).
- Secchi disk depth increased from 0.9 m to 2.6 m by the middle of May. From early June
to the middle of August, secchi disk depth declined ranging between 0.4 m to 1.5 m. The
rest of the season there was slight increase in secchi disk depth, but water transparency
remained below the standard limit (standard > 1.4 m). - Chlorophyll-a concentrations increased from early May to the middle of August peaking
at 89 μg/L. From late August chlorophyll-a concentrations decreased and then remained
consistent at 35 μg/L for the remainder of the season (standard < 14 μg/L). - Surface TP concentrations fluctuated between 44 μg/L and 62 μg/L from late April to
late September. In early October, TP concentrations increased to 101 μg/L about 2.5
times the standard limit (standard < 40 μg/L). Surface SRP concentrations were below
detection limit (< 0.005 μg/L) except in early May, middle of August, and late
September. - Bottom TP concentrations decreased from 151 μg/L to 42 μg/L in the beginning of the
season, and then peaked in the middle of July at 503 μg/L. From late July to late August,
TP concentrations declined again, and then increased to 392 μg/L in late September. By
early October, TP concentrations declined to 62 μg/L. Bottom SRP concentrations
followed a similar pattern to TP concentrations peaking in the middle of July (411 μg/L)
and late September (266 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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