4.15 Erosion Control

Goal 15 - Erosion Control

Control temporary sources of sediment resulting from land disturbance and identify, minimize and correct the effects of sedimentation from erosion-prone and sediment source areas.

Discussion

Erosion within the subwatershed can result in sediment being transported to lakes, wetlands, and streams, where it can degrade water quality and habitat.  Sediment accumulating in channels, culverts, and other facilities can reduce their ability to convey stormwater, while erosion can undermine their stability.

Restoration of lakeshore with native vegetation would help increase or maintain infiltration rates; decrease or maintain runoff rates and pollutant conveyance to water resources; help create fish and wildlife habitat; and help minimize erosion.    Identifying, addressing, and preventing erosion is necessary to meet District goals as well as to meet state and federal nondegradation, water quality and biological integrity requirements and to prevent the need for future TMDLs. 

Requiring new development and redevelopment to infiltrate some of the new stormwater generated would reduce post-development volumes downstream and help reduce future erosion in streams and channels; minimize new pollutant loading that would have been conveyed by that stormwater; and help maintain groundwater levels, preserving wetlands.

Strategies in the Langdon Lake subwatershed will focus on identifying erosion problems and working with LGUs to correct them, as well as considering potential downstream impacts of new volumes discharged from development.

Desired Outcomes:  Reduction in pollutant loading of temporary and permanent nature from erosion to supplement other goals.

Metrics:

  1. In-lake nutrient concentrations/Trophic State Index Scores (TSI) for Langdon Lake
  2. Nutrient loading goals (lbs) for Langdon Lake

Goal 15.1 - Langdon Lake

Identify and address erosion problems in the subwatershed.

Actions

  1. Identify, inventory, and prioritize gully and other erosion problems.
  2. The HHPLS modeled higher than desirable velocities in culverts under the railroad bed.  Work cooperatively with the Cities of Mound and Minnetrista to evaluate the need to provide erosion control or take energy dissipation measures at these crossings to prevent erosion and downstream sediment transport.
  3. Work cooperatively with LGUs to address identified erosion problems.
  4. Regulate new development and redevelopment and ensure compliance with erosion control standards.

Goal 15.2 - Langdon Lake

Manage water volumes to the channel between Saunders and Langdon Lakes to prevent further erosion.

Actions

  1. Implement the regulatory and management activities identified in this plan.
  2. Inspect that channel periodically to assess its condition.
  3. Work cooperatively with the Cities of Mound and Minnetrista to reduce volumes as necessary.