2.5 Hydrologic Systems

The Department of Natural Resources? Public Waters Inventory identifies numerous basins within the Lake Minnetonka subwatershed as under the jurisdiction of the DNR (see Figure 10).  These include several lakes and numerous unnamed basins:

Table 3.  Public Waters in the Lake Minnetonka subwatershed.

Name/DNR ID #

Name/DNR ID #

Name/DNR ID #

Name/DNR ID #

Name/DNR ID #

Name/DNR ID #

Minnetonka (27-133 P)

Unnamed (27-830 W)

Unnamed (27-855 W)

Unnamed (27-881 W)

Unnamed (27-904 W)

Spray Island Marsh (27-946 W)

Peavey (27-138 P)

Unnamed (27-831 W)

Unnamed (27-857 W)

Unnamed (27-882 W)

Unnamed (27-905 W)

Unnamed (27-947 W)

Forest (27-139 P)

Unnamed (27-841 W)

Shaver (27-86 P)

Unnamed (27-883 W)

Unnamed (27-907 W)

Unnamed (27-948 W)

French Marsh (27-140 P)

Unnamed (27-845 W)

Unnamed (27-863 W)

Unnamed (27-884 W)

Unnamed (27-908 W)

Unnamed (27-949 W)

William (27-142 P)

Unnamed (27-846 W)

Unnamed (27-866 W)

Unnamed (27-893 W)

Unnamed (27-909 W)

Unnamed (27-950 W)

Galpin (27-144 P)

Unnamed (27-847 W)

Maplewood Pond (27-867 W)

Unnamed (27-894 W)

Unnamed (27-910 W)

Unnamed (27-956 W)

Classen (27-162 P)

Unnamed (27-848 W)

Unnamed (27-869 W)

Unnamed (Mud) (27-895 W)

Unnamed (27-911 W)

Unnamed (27-957 W)

Lost (27-180 W)

Unnamed (27-849 W)

Marion (27-87 P)

Unnamed (College) (27-896 W)

Unnamed (27-912 W)

Unnamed (27-958 W)

Unnamed (27-742 W)

Libbs (27-85 P)

Louise (27-870 W)

Unnamed (27-897 W)

Unnamed (Pond H) (27-913 W)

Unnamed (27-964 W)

Unnamed (27-743 W)

Unnamed (27-850 W)

Hooper (27-876 W)

Unnamed (27-898 W)

Unnamed (Pond G) (27-914 W)

Unnamed (27-965 W)

Unnamed (27-744 W)

Unnamed (27-851 W)

Unnamed (27-877 W)

Mary (27-899 W)

Unnamed (27-915 W)

Unnamed (27-966 W)

Unnamed (27-745 W)

Ferndale Marsh (27-852 P)

Unnamed (27-878 W)

Unnamed (27-901 W)

Unnamed (27-943 W)

Unnamed (27-1095 W)

Unnamed (27-746 W)

Unnamed (27-853 W)

Unnamed (27-879 W)

Unnamed (27-902 W)

Unnamed (27-944 W)

Unnamed (27-1096 W)

Unnamed (27-747 W)

 

Unnamed (27-854 W)

Unnamed (27-880 W)

Unnamed (27-903 W)

Unnamed (27-945 W)

 

Source: Minnesota DNR.  See Figure 10.

The HHPLS included detailed modeling of the current and 2020 hydraulic and hydrologic conditions in the subwatershed.  That modeling includes the following results for modeled locations (lakes, ponds, channels, and crossings) within the subwatershed:

  • Existing Normal Water Level;
  • Existing High Water Level, peak discharge, and peak velocity for the 1.5 year, 24-hour and 100-year, 24-hour events;
  • 2020 predicted HWL, peak discharge, and peak velocity for the 100-year, 24-hour event; and the
  • Existing High Water Level for the 100-year, 10-day snowmelt event.

Those detailed results are not reproduced here, but are incorporated by reference.  The HHPLS model predicted that development in the subwatershed would not significantly impact high water levels or rates of discharge for most of the subwatershed, but development within the Halsteds Bay minor subwatershed and the Peavey Lake minor subwatershed may result in some increases in local high water levels.   Development in the Halsteds Bay subwatershed may increase sediment transport, further negatively impacting Halsteds Bay water quality.  There are several landlocked basins and subwatershed units, including Marion Lake, Mary Lake, Shavers Lake, and William Lake.

Table 4.  Modeled peak discharge from the Lake Minnetonka subwatershed (cfs).

 

1.5 year, 24 hour

100 year, 24 hour

 

Subwatershed

Existing

Existing

2020

Snowmelt

Browns Bay

0.0

0.6

0.6

1.5

Classen Creek

43.1

115.3

115.8

92.7

Carsons Bay

6.8

14.6

14.6

11.2

East Upper

28.1

54.7

55.1

46.8

Forest Lake

4.1

33.8

33.7

33.1

French Marsh

4.4

19.4

19.5

26.0

Galpin Lake

10.0

11.9

11.8

11.9

Grays Bay

*

*

*

*

Halsteds Bay

78.8

167.1

174.7

144.8

Lost Lake

*

*

*

*

Lake William

0.0

0.0

0.0

0.0

Mary Lake

0.0

0.0

0.0

0.0

Maplewood Pond

2.8

6.3

6.4

5.5

Peavey Lake

*

*

*

*

Robinsons Bay

1.5

3.3

3.3

4.0

Stubbs Bay

10.0

35.1

35.1

37.2

South Lower Lake

5.2

12.3

12.2

8.6

Tonka Bay

4.0

17.1

17.1

13.8

Wayzata Bay

64.1

122.2

122.1

39.0

*Equalized with Lake Minnetonka.  Discharge controlled at Grays Bay dam.

Source:  2003 MCWD Hydrologic, Hydraulic, and Pollutant Loading Study (HHPLS)