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

The primary strategy in the management of stormwater and prevention of flooding in the Minnehaha Creek subwatershed is the preservation of the stormwater storage.   Key areas identified in this plan for conservation include wetlands that provide floodplain storage and areas that provide channel and stream floodplain and riparian zones.

Desired Outcomes:  No net loss of floodplain storage.

Metrics:  Acres net floodplain fill

Goal 13.1 - Minnehaha Creek

Preserve the existing water storage capacity below the 100-year event elevation.

Actions

  1. Minimize development below the 100-year event elevation.
  2. No net loss of the wetlands that provide upstream stormwater storage within this subwatershed.
  3. Evaluate dredging of sediment accumulated upstream of impoundments and control structures to maximize in-channel storage.
  4. Encourage the development and maintenance of depressional storage within the subwatershed.
    1. Promote the acceptability of minor flooding within the floodplain.

Goal 13.2 - Minnehaha Creek

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

Actions

  1. The HHPLS noted that the 100-year water level was expected to overtop several public streets and trails.  Work together with the respective communities to determine specific impacts and potential improvements.