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WATER QUALITY by Rex Keister

Soon after the Spider Lake Property Owners Association (SLPOA)     was organized, it was determined that a need existed for a lake management program to protect the quality of the lake. Because of the investment each of us has made to live on the lake, whether year round or only weekends, our property values are directly affected by the lake’s quality and vitality.  Since the lake has no inlet or outlet, whatever we put into the water stays there.

To accomplish a meaningful management program, we partnered with the Department of Environmental Quality (DEQ) and the Michigan Lake & Stream Associations (ML&SA) to implement the Cooperative Lakes Monitoring Program (CLMP).  This program consists of monitoring indicators of water quality and documenting changes over time.

Since 1997, the SLPOA has monitored Secchi disk transparency, total phosphorus and chlorophyll a.  The results of this monitoring program are included in the data sets and graphs in the attachment.

Transparency readings have been taken at three locations:  Site #1 (deep basin at the NW end of the lake; Site #2 (West of island #3) and Site #3 (SW of island #1).  The deeper the clarity, the better.  Low clarity readings could indicate the possibility of high nutrient levels, high seasonal algal densities, or turbidity caused by boat traffic.  The graph indicates that Site #1 has the best clarity, followed by Site #2, and lastly, Site #3. The graph shows a potential declining trend.

Phosphorus is the most important nutrient, the limiting factor, for algae growth.  Spring samples indicate that, with the exception of one reading, all meet the acceptable level of 10 parts per billion (ppb).  Late summer graph indicates a higher surface concentration of phosphorus compared to spring “turn-over” levels, along with two spikes and a trend that shows a worsening.

Chlorophyll monitoring started in 1998.  Chlorophyll is the green photosynthetic pigment in the cells of plants.  The lower the level, the better, and the desired level is 3 ppb.  The graph shows that only four of the eight yearly averages are at or below the desired level.

In conclusion, the overall quality level of Spider Lake is good.  However, all indicators show there is a gradual deterioration taking place:  declining transparency, spikes in phosphorus levels, and chlorophyll levels slightly higher than the desired 3 ppb.   

Please pay attention to those human activities that speed up the lake’s aging process.  Are you maintaining your septic system?  Is your system adequate to protect our resource?  Are you fertilizing your lawn with fertilizers containing phosphorus? (non-phosphorus available at McGough’s and Kingsley Co-op)   Are you using chemicals on your lawn that will end up in the lake and ground water?  Are your boating habits causing soil erosion and turbidity?  Are you taking precautions to keep exotics out of the lake?  Are you using this lake for recreation, fishing, and the like?  Are you a member of, and financially supporting the SLPOA?   We need your help keeping our lake healthy – thank you, sincerely.

Data sets and graphs prepared by Justin Kulesza