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.

The key areas identified in this plan for conservation activities include buffer zones adjacent to streams and channels.  In some cases these buffer zones are riparian or flow-through wetlands, and those wetlands have been identified as key conservation areas.  Where streams and channels flow through upland areas, conservation of native vegetation within these zones would also increase or maintain infiltration rates; decrease or maintain runoff rates and pollutant conveyance to water resources; and help minimize erosion.   Restoration of lakeshore would have the same benefits.  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 Dutch Lake subwatershed will focus on identifying erosion problems on an ongoing basis 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:

  • In-lake nutrient concentrations/Trophic State Index Scores (TSI) for Dutch Lake
  • Nutrient loading goals (lbs) for Dutch Lake
  • Linear feet of shoreline protected in Key Conservation Areas
  • Linear feet and width of riparian areas protected in Key Conservation Areas

Goal 15.1 - Dutch 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 at the Game Farm Road culvert between DL-6 and DL-7 (west of Highway 110) that could lead to inlet or outlet erosion.  Work cooperatively with the City of Minnetrista to evaluate the need to provide erosion control or take energy dissipation measures at this crossing to prevent erosion and downstream sediment transport.
  3. Work cooperatively with LGUs to restore spot erosion problems on streambanks on Dutch Creek as well as other identified erosion problems.
  4. Regulate new development and redevelopment and ensure compliance with erosion control standards.

Goal 15.2 - Dutch Lake

Manage water volumes to Dutch Creek to prevent further erosion.

Actions

  1. Implement the regulatory and management activities identified in this plan.
  2. Inspect erosion-prone areas of Dutch Creek periodically to assess its condition.
  3. Work cooperatively with the adjacent property owners and LGUs to prevent erosion and sediment transport and stabilize to streambanks as necessary.