Water Testing on Lake D The dark square below shows the range of data for hundreds Wi. lakes. The + represents where Lake D compares to the rest View the 2025 DNR Lake D Status Water testing trends on Lake D over time High levels are caused by boat traffic and runoff , resulting in algae blooms, and loss of lake clsrity Scchi depth or clarity depends on algae growth, temperature, time of year and boating activity Phosphous provides the nutrient and Chlorophyll captures sunlight for photsyntherthis making energy Our Own Testing Data since 2008 .. There are many things we can do to reduce algae growth and improve lake quality. The link below will get you started Algae Bloom Lake D