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 and maintain 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 Christmas Lake
  • Nutrient loading goals (lbs) for Christmas Lake

Goal 3.1 - Christmas Lake

Achieve and maintain an in-lake total phosphorus concentration goal of 15 μg/L in Christmas Lake.

Actions

  1.  Conduct a diagnostic study to investigate and determine the likely causes of the slow decline in water quality in Christmas Lake and develop options for reversing that trend.
  2. Require LGUs to reduce phosphorus loading from developed uses upstream of Christmas Lake by a minimum of 10 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. 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.
  4. Sponsor educational opportunities for LGU staff, developers, elected and appointed officials and other interested parties to provide practical information and opportunities for sharing experiences.
  5. 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.
  6. Continue regular water quality monitoring in Christmas Lake to assess progress toward maintaining the in-lake phosphorus goal.

Goal 3.2 - Christmas Lake  

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

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 - Christmas Lake  

Minimize pollutant loading contribution to St Albans Bay from Christmas Lake.

Actions

  1. Maintain Christmas Lake in-lake total phosphorus concentration goal.
  2. Inspect the channel draining the upper subwatershed at least annually to assess whether erosion is occurring.
  3. Work cooperatively with the City of Chanhassen to manage flows in the channel to prevent erosion and sediment transport and stabilize streambanks as necessary.