3.1 Water Quality

  1. The water quality in Dutch Lake since 2000 has consistently been scored in the C-D grade range on the District's annual lake report cards.  The mean summer 2004 total phosphorus concentration was 88 ?g/L, well in excess of the District's 40 ?g/L goal and the highest average concentration since 1997.   Based on this monitoring history Dutch Lake's water quality is not supportive of swimming.
  2. The HHPLS identified a need to reduce phosphorus loading by approximately 42 percent to achieve the desired goal of 40 ?g/L, as well as to reduce nitrogen and total suspended solid loadings.  The HHPLS and modeling performed for this plan also noted that internal phosphorus loading and possibly phosphorus export from wetlands in the subwatershed were likely significant sources of excess phosphorus in the lake.
  3. Development, redevelopment, and reconstruction in the subwatershed will increase nutrient and TSS loads from the watershed as well as increasing the volume of stormwater runoff, potentially further degrading water quality in Dutch Lake and streams and wetlands in the subwatershed.