4.3 Water Quality

Goal 3 - Water Quality

Preserve, maintain and improve aesthetic, physical, chemical and biological composition of surface waters and groundwater within the District.

Discussion

The HHPLS used an extensive public input process to establish water quality goals for the primary receiving waters in the District, focusing primarily on identifying target total phosphorus concentrations.  This plan identifies those plus additional goals related to water quality.  This plan sets forth a set of actions the District will undertake to reduce pollutant loading in the subwatershed and achieve water quality goals.  The achievement of these water quality goals is not only necessary to meet state and federal water quality requirements and to prevent future TMDLs, but also to meet this plan’s ecological integrity goals.

Desired Outcomes:  Achievement of in-lake nutrient concentration goals through achievement of nutrient loading reductions.

 Metrics:

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

Goal 3.1 - Dutch Lake

Achieve and maintain the in-lake total phosphorus concentration goal of 40 μg/L in Dutch Lake.

Actions

  1. Conduct a diagnostic study of internal lake phosphorus loading, prepare a feasibility study, and construct improvements to reduce internal loading by at least 70 percent.
  2. Conduct a diagnostic study of wetland nutrient cycling and phosphorus export, prepare a feasibility study, and construct improvements to reduce phosphorus export by at least 50 percent.
  3. Consider amending existing or establish new District rules requiring greater than 50 percent phosphorus removal on new permitted developments within the Dutch Lake subwatershed.
  4. Require LGUs to reduce phosphorus loading from developed and agricultural uses upstream of Dutch Lake by a minimum of 25 pounds per year within 10 years.
    1. Provide education and training opportunities, technical and planning assistance for property owners and LGUs on methods to reduce phosphorus and sediment loading by incorporating BMPs into landscaping, agriculture, infrastructure maintenance, and reconstruction.
  5. Provide assistance to LGUs and developers to foster low impact development and redevelopment that minimizes new phosphorus and sediment loading.
    1. Develop and distribute model ordinances and design standards that incorporate low impact design principles.
    2. Sponsor educational opportunities for LGU staff, developers, elected and appointed officials and other interested parties to provide practical information and opportunities for sharing experiences.
  6. Promote the general application of BMPs across the subwatershed.
    1. Consider developing a small grant program to provide financial assistance to property owners desiring to retrofit their property with BMPs to reduce phosphorus and sediment loading.
  7. Continue regular water quality monitoring in Dutch Lake to assess progress toward achieving the in-lake phosphorus goal.

Goal 3.2 - Dutch Lake

Achieve and maintain other state lake water quality standards in Dutch Lake including >1.4 m Secchi clarity and 14 ug/L chl-a.

Actions

  1. Achieve and maintain in-lake total phosphorus goals.
  2. Manage aquatic vegetation in accordance with a vegetation management plan that takes into account water clarity goals.
  3. Develop a water quality index which encompasses the District’s broader definition of water quality.

Goal 3.3 - Dutch Lake

Minimize pollutant loading contribution to Jennings Bay from Dutch Creek and its direct drainage area.

Actions

  1. Achieve Dutch Lake in-lake total phosphorus concentration goal.
  2. Require LGUs to reduce phosphorus loading from developed and agricultural uses downstream of Dutch Lake as identified in the HHPLS by a minimum of 3 pounds per year within 10 years.
    1. Provide education and training opportunities, technical and planning assistance for property owners and LGUs on methods to reduce phosphorus and sediment loading by incorporating BMPs into landscaping, infrastructure maintenance, and reconstruction.
  3. Inspect erosion-prone areas of Dutch Creek at least annually to identify any new areas of erosion.
  4. Work cooperatively with the City of Mound to reduce water volumes to Dutch Creek.
  5. Continue to monitor water quality in Dutch Creek.