Lake Minnewashta (DNR ID: 10-0009-00)
Sampling Location GPS Coordinates: Surface Area: 738 acres Max. Depth: 70 ft
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From State Hwy 7 just west of Excelsior, take Hwy 41(Hazeltine Blvd.) south for half a mile. Take a right into Lake Minnewashta Regional Park to gain access to the lake.
Lake Minnewashta is a dimictic class 2B lake protected for aquatic life and recreation. Limited water quality information is available beginning in 1975, but regular seasonal sampling did not begin until 1997. It is currently listed as an impaired water body by the MPCA for mercury in fish tissues. MCWD staff have been monitoring the 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 early May 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. Additional samples were taken one meter below the thermocline mixing zone once stratification developed. Surface sample parameters analyzed included total phosphorus (TP), total nitrogen (TN), and soluble reactive phosphorus (SRP). Surface concentrations of chlorophyll-a were also analyzed and measurements of Secchi disc depth were recorded. Thermocline and bottom samples were analyzed for TP and SRP.
| 2008 Summer Water Quality Summary |
| Parameters | Range | Mean | TSI Value | Lake Grade |
| Months | June - Sept. | May - Sept. | ||
| Secchi Depth (m) | 2.3 - 4.6 | 2.9 | 45 | B |
| Surface TP (µg/L) | 15 - 26 | 19.1 | 47 | A |
| Chlorophyll-a (µg/L) | 2 - 12 | 6.7 | 49 | A |
| Overall Score | 47 | A- |
The following summary refers to Figure 5.3 (a-d).
- At the beginning of the season, secchi disk depth increased from 1.5 m to 4.6 m. Water clarity decreased in middle of June where the secchi disk depth remained about 2.7 m until the end of September. Secchi disk depth continued to decrease at the end of the season.
- Chlorophyll-a concentrations decreased from 25 µg/L to 5 µg/L in May. Concentrations remained below the standard (< 15 µg/L) throughout the rest of the season until the end of October.
- Surface TP concentrations were below the standard (< 40 µg/L) for the entire season. Early in the season, concentrations decreased then slightly increased in June. TP concentrations did not increase again until the end of the season. Surface SRP concentrations remained below detection limits except in early June.
- Both bottom TP and SRP concentrations gradually increased throughout the entire 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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