Long Lake (DNR ID: 27-0160-00) MCWD Site ID: LLO01 Sampling Location - GPS Coordinates: Surface Area: 261 acres Max. Depth: 33 ft
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Long Lake is located in the city of Long Lake and public lake access is available one block northeast of US Hwy 12 off Lake Street. There is both a public boat access and a recreational park with beach.
Long Lake 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 1996. 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. 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. 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) | 0.7 - 2.2 | 1.3 | 56 | C |
| Surface TP (µg/L) | 38 - 105 | 53.6 | 62 | C |
| Chlorophyll-a (µg/L) | 15 - 76 | 40.1 | 67 | C |
| Overall Score | 62 | C |
The following summary refers to Figure 11.3 (a-d).
- Secchi disk depth fluctuated between 0.7 m to 2.2 m from May to early August. The remainder of the season the secchi disk depth continued to fluctuate, but the range decreased from 0.85 m to 1.3 m.
- Chlorophyll-a concentrations fluctuated in the early season then gradually increased to 76 µg/L by late September. Concentrations continued to fluctuate the remainder of the season with the largest concentration occurring at the end of October (79 µg/L).
- Surface TP concentrations decreased from 81 µg/L to 32 µg/L in May. From June to August, concentrations remained consistent, until September when TP concentrations increased to 106 µg/L. By the end of the season, concentrations had decreased. Surface SRP concentrations were below detection limits, until October, when concentrations reached a high of 6 µg/L.
- Both bottom TP and SRP concentrations steadily increased until September, when concentrations sharply decreased. The rest of the season phosphorus concentrations continued to decrease.
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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