2.5.1 Lakes

The subwatershed is dominated by Lake Minnetonka with its complex configuration of bays and channels.

Table 5 and Table 6 below detail the physical and water quality characteristics of the lake.  The HHPLS modeled water quality and established goals for twenty-six of those bays.  An additional eight lakes had established goals in the 1997 plan but those goals were not modeled in the HHPLS.  Many of the bays are monitored as part of the District’s monitoring program.  Little or no water quality data is available for smaller lakes scattered throughout the subwatershed.    

The streams that drain the other subwatersheds in the upper watershed convey significant phosphorus and sediment loads to the lake, and are a major cause of the poor water quality in some of the bays.  In decades past, several sewage treatment plants operated in the upper watershed, and their discharges conveyed significant phosphorus loads to the lake.  Since those plants discontinued operation, the water quality in the Lake has improved considerably, but those old discharges may continue to influence water quality from phosphorus in the lake sediments.

Table 5.  Physical characteristics of lakes in the Lake Minnetonka subwatershed.

Lake 

Surface Area (acres)

Maximum Depth(ft)

Watershed to Lake Area Ratio

DNR Classification

Lake Minnetonka

14,004

113

5:1

Recreational Development

Peavey Pond

9

73

85:1

N/A

Lake Marion

12

N/A

27:1

Recreational Development

Shavers Lake

13

N/A

7:1

Recreational Development

Louise Lake

7

N/A

18:1

N/A

Libbs Lake

23

8

4:1

General Development

Forest Lake

84

42

10:1

General Development

Lake Galpin

48

13

10:1

Recreational Development

Lost Lake

N/A

N/A

2:1

N/A

Classen Lake

53

N/A

5:1

Natural Environment

Source: Minnesota DNR

Table 6.  Selected water quality goals and current conditions of lakes in the Lake Minnetonka subwatershed.

Bay

1997 TP Goal (μg/L)

HHPLS TP Goal (μg/L)

1997-2004 Average TP (μg/L)

2004

TP (μg/L)

Chl-a (μg/L)

Secchi (m)

TSI

Black

50

45

-

40

10

7.7

54

Browns

30

20

22

N/A

N/A

N/A

N/A

Carmens

50

50

-

24

4

2.7

46

Carsons

50

50

-

21

1

3.1

42

Cooks

50

30

33

32

16

1.9

54

Crystal

30

25 - 30

28

26

9

3.0

49

East Upper

none

none

-

29

4

2.7

47

Gideons

none

none

-

22

2

3.3

42

Grays

50

20

-

21

1

3.3

40

Halsteds

50

50 - 60

119

128

41

1.6

65

Harrisons

50

50

63

58

32

1.2

61

Jennings

90

50 - 70

111

110

39

1.4

65

Lafayette

50

20

23

N/A

N/A

N/A

N/A

Lower Lake South

30

20

21

20

6

3.3

46

Maxwell

50

40

33

32

12

2.4

52

North Arm

50

30

32

31

11

2.4

52

Phelps

50

20

-

N/A

N/A

N/A

N/A

Priest

50

30

-

55

28

1.0

62

Robinsons

none

30

-

N/A

N/A

N/A

N/A

Seton

50

100

-

N/A

N/A

N/A

N/A

Smiths

50

50

-

N/A

N/A

N/A

N/A

Smithtown

none

none

-

23

5

2.3

48

Spring Park

50

20

23

20

7

2.9

47

St. Albans

50

20

22

16

4

3.9

43

St. Louis

none

50

-

N/A

N/A

N/A

N/A

Stubbs

50

50 - 55

59

63

30

1.6

60

Wayzata

42

20

20

17

6

3.4

45

West Arm

50

50

71

59

33

1.6

60

West Upper

none

25

28

27

12

2.4

51

 Table 7.  Selected water quality goals and current conditions in the minor Lake Minnetonka subwatershed and direct drainage lakes.

Lake 

1997 TP Goal(μg/L)

HHPLS TP Goal (μg/L)

1997-2004 Average TP (μg/L)

2004

TP (μg/L)

Chl-a (μg/L)

Secchi (m)

TSI

Peavy Pond

None

*

66

76

17

2.1

58

Lake Marion

None

*

N/A

N/A

N/A

2-4***

N/A

Shavers Lake

None

*

N/A

N/A

N/A

N/A

N/A

Louise Lake

None

*

N/A

N/A

N/A

N/A

N/A

Libbs Lake

None

30

30

21

2

1.8

46

Forest Lake

None

None

67

71

21

1.7

59

Lake Galpin

None

60

40

30**

18

2.1

54

Lost Lake

None

None

N/A

N/A

N/A

N/A

N/A

*10% reduction of the existing TP concentration provided it is above 25 μg/L; will require baseline data

**2003 data *** Clarity as estimated by the University of Minnesota using satellite imagery