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.  Steep slopes such as those on the east shore of Christmas Lake are prone to erosion and can negatively impact the lake’s exceptional water quality and clarity.   The HHPLS identified the channel draining the upper subwatershed as another potential location prone to 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.  Limiting discharges from subwatersheds and basins that are currently landlocked is necessary to prevent further degradation of downstream water quality as well as to limit new volumes discharged to channels that are already experiencing erosion.

Strategies in the Christmas Lake subwatershed will focus on identifying erosion problems and working with LGUs and property owners to correct them.  Identifying existing eroded shoreline locations and potential future locations for shoreline restoration is a priority, as is working cooperatively with the City of Chanhassen to evaluate restoration potential along the upper subwatershed channel. 

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

Metrics:

  • In-lake nutrient concentrations/Trophic State Index Scores (TSI) for Christmas Lake
  • Nutrient loading goals (lbs) for Christmas Lake

Goal 15.1 - Christmas Lake

Identify and address erosion problems in the subwatershed.

Actions

  1. Identify, inventory, and prioritize steep slope, shoreline and other erosion problems.

  2. Work cooperatively with LGUs to address identified erosion problems.

  3. Regulate new development and redevelopment and ensure compliance with erosion control standards.

Goal 15.2 - Christmas Lake

Manage water volumes to the channel draining the upper subwatershed to prevent further erosion.

Actions

  1. Implement the regulatory and management activities identified in this plan.

  2. Inspect the upper subwatershed channel periodically to assess its condition.

  3. Work cooperatively with the City of Chanhassen to reduce stormwater volumes to prevent erosion and sediment transport and stabilize streambanks as necessary.