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.   In addition, two lakes in this subwatershed are currently undergoing development of a TMDL to reduce excess nutrient 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 Halsteds Bay and the lakes within the subwatershed
  • Nutrient loading goals (lbs) for Halsteds Bay and the lakes within the subwatershed

Goal 3.1 - Six Mile Marsh

Achieve in-lake total phosphorus concentration goals as identified in this plan and the lake TMDLs.

Actions

  1. Conduct a diagnostic study of internal or unknown lake phosphorus loading in Stone Lake and on East and West Auburn Lakes, prepare a feasibility study, and implement improvements to reduce internal or unknown loading by at least 70 percent.
  2. Consider amending existing or establishing new District rules requiring greater than 50 percent phosphorus removal on new permitted developments within the Six Mile Marsh subwatershed.
  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.
    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.
  4. 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.
  5. Continue regular water quality monitoring in the lakes to assess progress toward achieving the in-lake phosphorus goals. 
    1. Require LGUs to maintain or reduce phosphorus loading from developed uses as set forth in Section 5.6.1 of this plan within 10 years. 
  6. 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.

Goal 3.2 - Six Mile Marsh

Achieve and maintain other state lake water quality standards including >1.4 m Secchi clarity and 14 ug/L chl-a for deep lakes, and >1.0 m Secchi clarity and 20 ug/L chl-a for shallow lakes.

Actions

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

Goal 3.3 - Six Mile Marsh

Prevent degradation of existing water quality in Carl Krey, Church, Turbid, and Mud Lakes.

Actions

  1. Obtain baseline water quality data for Carl Krey, Church, Turbid, and Mud Lakes and update every three to five years.

Goal 3.4 - Six Mile Marsh

Minimize pollutant loading contribution to Halsteds Bay from Six Mile Creek.

Actions

  1. Inspect known erosion-prone areas of Six Mile Creek at least annually to assess its condition, and the entire creek at least every five years.
  2. Repair identified erosion locations in Six Mile Creek and develop strategies to prevent future erosion and sediment transport.
  3. Continue to investigate possible causes of periodic low dissolved oxygen in Six Mile Creek and develop strategies to minimize periods of low dissolved oxygen.
  4. Continue to monitor water quality in Six Mile Creek.