"Pump lake water into your irrigation system to irrigate and “fertilize” your lawn and landscape plants instead. The lake water will naturally contain nitrogen and phosphates for your plants and lawn and the remaining nutrients will leach into your soil and return to the lake via ground water". If you must fertilize, follow guidelines such as these from Glen Lake Association.
Take precautions to keep boat fuel spills, cleaners and all soaps out of the lake. Don't rake leaves or grass clippings into the water which create excess nutrients. Don't feed waterfowl. Clean watercraft coming from other lakes and streams thoroughly to prevent invasive hitch-hikers.
This is a great resource for lake property owners. Take the survey, learn a lot, get a certificate!
Be a Little Traverse Lake Protector!