Black Lake (DNR ID: 27-0133-06)
Sampling Location GPS Coordinates: Surface Area: 25 acres Max. Depth: 25 ft
|
|
|
Black Lake is located in Spring Park. Head east on Minnetonka Blvd, and turn right on Co Rd 101 S. Turn right MN-7 and turn right on Oak St. Oak St. merges into Smithtown Rd and continue onto Manitou Rd/Shadywood Rd. 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. Black Lake is adjacent to Spring Park Bay and Seton Lake. Water quality data is available beginning in 2004. MCWD staff have been monitoring the site on Black 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.
| 2008 Summer Water Quality Summary |
| Parameters | Range | Mean | TSI Value | Lake Grade |
| Months | June - Sept. | May - Sept. | ||
| Secchi Depth (m) | 1.6 - 3.6 |
2.3 |
48 |
B |
| Surface TP (µg/L) | 24 - 32 |
28.4 |
52 |
B |
| Chlorophyll-a (µg/L) | 3 - 18 |
9.7 |
53 |
A |
| Overall Score | 51 |
B+ |
The following summary refers to Figure 3.3 (a-d).
- From late April to the middle of July, there was an overall increase in secchi disk depth. From July to early August, secchi disk depth decreased from 2 m to 1.6 m. The rest of the season, secchi disk depth ranged from 1.6 m to 2.4 m (standard > 1.2 m).
- Chlorophyll-a concentrations decreased from 22 µg/L in late April to 5 µg/L in late May. From June to middle of July, concentrations ranged between 3 µg/L to 5 µg/L. The remainder of the season, there was an overall increase in chlorophyll-a concentrations ranging from 8 µg/L to 18 µg/L (standard < 15 µg/L).
- Surface TP concentrations remained below the standard limit for the entire season (< 40 µg/L). Concentrations decreased from 39 µg/L to 27 µg/L by early May. The rest of the season, TP concentrations remained consistent between 26 µg/L and 33 µg/L. Surface SRP concentrations remained below the detection limit (< 0.005 µg/L) for the entire season.
- Bottom TP concentrations increased from 35 µg/L to 69 µg/L in the beginning of the season to early June. Concentrations again increased from 54 µg/L to 140 µg/L between July and early August then decreased to 96 µg/L by the end of the month. The remainder of the season, concentrations ranged between 31 µg/L and 36 µg/L. Bottom SRP concentrations remained below detection limit (< 0.005 µg/L) except at the end of May, early June, and early August.
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.
|
|
Links to PDF documents in this site require Adobe Acrobat Reader, which you can download for free by clicking on the image below. (this will open in a separate browser window)
