2.5 Hydrologic Systems

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

Table 3.  Public Waters in the Six Mile Marsh subwatershed.

DNR ID #    Name

DNR ID #     Name

DNR Public Waters Watercourses

10-41P

Zumbra-Sunny Lake

27-959W

Unnamed

Six Mile Creek Sec 10 T116R24 to Sec 9 T116R24

10-42P

Parley Lake

10-200P

Unnamed

10-43P

Lunsten Lake

10-201W

Unnamed

Unnamed watercourse to Lunsten

10-44P

Auburn Lake

10-197W

Unnamed

Unnamed watercourse to Auburn

10-45P

Steiger Lake

10-194P

Unnamed

Unnamed watercourse to Auburn

10-48P

Wassermann Lake

10-193P

Unnamed

Unnamed tributary

10-49W

Auburn Marsh

10-192P

Unnamed

Unnamed tributary

10-53P

Piersons Lake

10-191W

Unnamed

Unnamed watercourse to Wasserman

10-54P

Marsh Lake

10-190W

Unnamed

Unnamed watercourse to Marsh

10-56P

Stone Lake

10-145W

Unnamed

Unnamed watercourse to Auburn

10-46P

Church Lake

10-143W

Unnamed

Unnamed watercourse to Auburn

10-51W

Turbid Lake

10-142P

Unnamed

Unnamed watercourse to Zumbra

27-133P

Lake Minnetonka

10-141P

Unnamed

 

27-960W

Six Mile Marsh

10-140P

Unnamed

 

27-186P

Mud Lake

10-139P

Unnamed

 

10-50P

Carl Krey Lake

10-138P

Unnamed

 

10-47P

Kelser's Pond

10-137P

Unnamed

 

10-134P

Sunny Lake

10-136P

Unnamed

 

27-963W

Unnamed

10-135P

Unnamed

 

27-962W

Unnamed

10-133P

Unnamed

 

27-961W 

Unnamed

10-141P

Unnamed

 

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, particularly in the city of Victoria and along Highway 7 that are now lightly developed, agricultural, or wooded, would increase local discharges resulting in an overall increase in flow in Six Mile Creek by more than 30 cfs for the 100-year event   The model predicts that high water elevations on some individual wetland basins may increase slightly.   The HHPLS scour analysis identified one reach of Six Mile Creek as having high erosion potential based on soils; but no visible erosion was noted in that reach during the Stream Assessment.  The scour analysis revealed two other reaches of Six Mile Creek as having modeled velocity in excess of 1.5 fps for the 1.5 event; one of those reaches includes two areas of spot erosion noted in the Stream Assessment.  Three reaches on small streams elsewhere in the subwatershed were identified as having high erosion potential, but those tributaries were not surveyed in the Stream Assessment.

Table 4.  Modeled peak discharge from the Six Mile Marsh subwatershed (cfs).

Event

Existing

2020

Snowmelt

1.5 year, 24 hour

23.4

-

-

100 year, 24 hour

97.7

122.2

-

100-year, 10-day

-

-

51.0

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