Mona Lake enjoys equal or better water quality than other similar area lakes but the battle continues against ongoing issues with stream runoff feeding into Mona Lake. Mona Lake is rated as "good" by the US EPA and the water is classified as Eutrophic. The trophic classification system was developed to rate lakes based on clarity, Chlorophyll-A content and Phosphorous Content. Eutrophic lakes include some of the most highly prized recreational lakes in the state and may have excellent recreational water quality with few adverse conditions...
We have monitored the water in Mona Lake. The principal indicator of excess nutrients is the level of Phosphorus (P). P levels have decreased over time. Water clarity has also improved. Likely contributing factors include:
- Muskegon County banned P in fertilizers ten years ago.
- The US Dept. of Agriculture has installed over 500 acres of vegetated, filter strips between farm fields and streams feeding Mona Lake.
- Numerous homeowners are using bubblers. This increases the oxygen content of the lake which acts to reduce P content.
The MLIA has been treating to control invasive milfoil for over ten years. The cost is reasonable when it is done regularly but becomes extremely expensive if it is allowed to get out of control. The improvements we are seeing in water quality have led to the return of native species of weeds which can also be annoying and can foul water craft drives. The native weeds tend to grow in mid to late season. We have added a mid-season assessment and a tailored spray application in early August.