Powderhorn Lake (DNR ID: 27-0014-00)
Sampling Location - GPS Coordinates: Surface Area: 11 acres Max. Depth: 20 ft |
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Powderhorn Lake is located in Minneapolis. 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 right onto the ramp to US-12 E and continue onto US-12 E. Merge onto I-394 E and take exit 8B for I-94 W/I-94 E. Keep right at the fork, and continue onto I-94 E. Next take exit 234A for Hiawatha Ave/State Hwy 55. Merge onto Hiawatha Ave/MN-55. Turn right at E. 28th St., then a left at Cedar Ave S. Next turn right at E. Lake St. and then turn left at 13th Ave S. 13th Ave S will dead-end onto Powderhorn Terrace. Go left on Powderhorn Terrace and turn right on 14th Ave S. Powderhorn Lake will be on the right.
Powderhorn Lake is a shallow, polymictic class 2B lake protect for aquatic life and recreation. It has an island and one deep hole at the southeastern end of the lake. Water quality data is available back to 2002. Currently, Minneapolis Park and Recreation Board (MPRB) staff monitors the lake on a bi-weekly basis and send MCWD the raw data each fall.
Powderhorn Lake was named after the original shape which resembled a powderhorn. In 1890, MPRB acquired the lake and dredging was conducted from 1894 to 1904. The south end of the lake was deepened by hydraulic dredging between 1924 and 1925 and about 150,000 cubic yards of material were used to fill the north half the lake to create parkland (MPRB, 2006).
Monitoring season started in early May and ended in late October by MPRB. Hydrolab mini-sonde 5 multi-probe measured dissolved oxygen (DO), temperature (oC), pH, and specific conductivity (µS/cm) at each meter depth from the water surface to the bottom. Surface water samples were a composite of the first two meters below the surface while bottom water samples were collected one meter from the bottom. Additional discrete samples were collected throughout the thermocline mixing zone once stratification developed. Surface sample parameters analyzed are extensive; MCWD is concerned with 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) | 0.7 - 1.97 |
1.0 |
60 |
D |
| Surface TP (µg/L) | 54 - 158 |
99.8 |
71 |
D |
| Chlorophyll-a (µg/L) | 6.5 - 24.9 |
14.3 |
57 |
B |
| Overall Score | 62 | C- |
The following summary refers to Figure 2.21 (a-d).
- Secchi disk depth decreased from late May to early July then gradually increased to 2.15 m by October. Secchi disk depth was above the standard (> 1.2 m) from late August to October.
- Chlorophyll-a concentrations increased from 8.8 µg/L to 48.4 µg/L by early May and decreased to 14.1 µg/L by early June. Concentrations increased to 24.9 µg/L in early July, then declined to about 6 µg/L by October (standard < 15 µg/L).
- Surface TP concentrations increased to 158 µg/L by early June, and then decreased to 38 µg/L by October (standard < 40 µg/L). Surface SRP concentrations increased to 31 µg/L by early June then declined for the remainder of the season.
- Both bottom TP and SRP concentrations declined in the early season, and then slightly increased in early June. The rest of the season both TP and SRP concentrations declined.
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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