4.13 Floodplains

Goal 13 - Floodplains

Reduce the severity and frequency of flooding and high water by preserving and increasing the existing water storage capacity below 100-year flood elevations on all waterbodies within MCWD.

Discussion

Flood Insurance Studies have identified no floodplain in the Christmas Lake subwatershed.  However, managing stormwater flows within this subwatershed is still important to help reduce the severity and frequency of localized flooding within the subwatershed.  The primary strategy in the management of stormwater in the Christmas Lake subwatershed is the preservation of the existing stormwater storage provided by wetlands.  Additional storage could be provided through the creation of depressional storage areas on new developments.

Desired Outcomes: No net loss of wetland storage.

Metrics:  Acres net wetland fill. 

Goal 13.1 - Christmas Lake

Preserve the existing water storage capacity.

Actions

  1. Minimize loss of the large wetland complexes that provide substantial upstream stormwater storage within this subwatershed.
  2. Encourage the development and maintenance of depressional storage within the subwatershed.

1.  Promote the acceptability of minor flooding within the low lying areas.

Goal 13.2 - Christmas Lake

Utilize District hydrologic and hydraulic data to identify potential public infrastructure high water impacts.

Actions

  1. The HHPLS noted that the natural swale outletting the unnamed wetland, DNR ID 27-892W (see Figure 10 for location), in subwatershed unit CL-2 is predicted to just overtop during the 100-year snowmelt event, which may impact Christmas Lake Road.   Local plans should identify these observed or potential locations and assess whether the risk of occasional flooding is acceptable or should be addressed.  Assist LGUs in determining specific impacts and potential improvements.