Water Quality & Quantity

2016 water results are in and here are the graphs.

Water Testing Results for 2016

Kendrick Bay, Black Jack Island and Oak Bay are all testing in the middle of the trophic scale or mesotrophic.  2013 saw an increase in phosphorus levels in all testing areas and 2014 showed very little change.  Our phosphorus data results for 2016 showed improvement in all three areas: Kendrick, by Black Jack Island and Oak Bay.  Mid lake (by English Island) showed a slight improvement.   I do not claim to understand all the science but it looks to me like we continue to improve our phosphorus levels.  Our Secchi depth levels also increased.  These show the clarity of the lake.  The levels haven’t been this high since 2012.  Our calcium levels have remained about the same.  When I googled calcium in lakes, I found that it has to do with the hardness/softness of the water.  Moderate soft is between 20 and 40 mg/L.  The past 2 summers have found us between 30 and 37 mg/L.

Our thanks to Dave Johnson for taking the secchi and phosphorus readings.

Phosphorus levels explained…

An oligotrophic lake (phosphorus 0-12 ug/L) is a lake with low primary productivity, the result of low nutrient content. These lakes have low algae production, and consequently, often have very clear waters, with high drinking-water quality. The bottom waters of such lakes typically have ample oxygen; thus, such lakes often support many fish species, like lake trout, which require cold, well-oxygenated waters.

Mesotrophic or moderately enriched lakes (phosphorus 12-24 ug/L)   are lakes with an intermediate level of productivity, greater than oligotrophic lakes, but less than eutrophic lakes. These lakes are commonly clear water lakes and ponds with beds of submerged aquatic plants and medium levels of nutrients.

An eutrophic or enriched (phosphorus 24-96 ug/L) body of water, commonly a lake or pond, has high biological productivity. Due to excessive nutrients, especially nitrogen and phosphorus, these water bodies are able to support an abundance of aquatic plants. Usually the water body will be dominated either by aquatic plants or algae.   When aquatic plants dominate the water tends to be clear. When algae dominates the water tends to darker. The algae engages in photosynthesis which supplies oxygen to the fish and biota which inhabit these waters. Occasionally an excessive algae bloom will occur and can ultimately result in fish kills due to respiration by algae and bottom living bacteria. The process of eutrophication can occur naturally and by human impact on the environment.

Dissolved Oxygen Water Testing – summer 2016.

For another season, Dissolved Oxygen levels were monitored in one of the deeper parts of the lake.  Most samples were collected between Lighthouse Point and English Island, in depths ranging from 60 to 80 feet. Dissolved Oxygen is important to various cold water species, including popular game fish. When organic sediments (such as decomposing weeds) from the surface sink to the bottom layers of deep water, the decomposition gradually depletes the oxygen available in these deeper areas. During much of the mid and later part of summer, the bottom layers of water do not mix with the surface water, so when deeper oxygen is depleted by decomposing sediments, it’s not replaced until the fall when lowering temperatures allow a mixing of deep and surface waters.

During the late spring and early summer of 2016, dissolved oxygen started in the 6 to 7 ppm (parts per million) range, considered good for most species, but dropped to the 2 to 3 ppm range in late summer. This lower range is considered marginal for survival of some aquatic organisms, including some desirable fish species.

The 2016 seasonal pattern has been generally consistent for the past few years. The late summer levels of D.O. indicate at least a moderate overabundance of organic sediments from such things as “weed” growth. This in turn usually relates to the nutrient levels (like phosphorus and nitrogen from development and agricultural sources) in the lake waters. Phosphorus sampling has been ongoing in Beverley Lake water for several years, in cooperation with the “Lake Partners” program, with results generally placing the lake in a middle level of concern for phosphorus levels.   (For more information on phosphorus levels, see the Lake Partners program on the Ministry of Environment website.)

 

Previous Water Quality Reports:

Lower-Beverley-Lake-Water-Quality-through-2002

1971 Water quality report p1-16

1971 Water quality report p17-33

1971 Water quality report p34-49

Water Depth:

91.85 is the summer target depth.  Our depth is regulated at the Lyndhurst Dam by MNR.  There is a gauge on the side of the dam closest to Wings. MNR checks it often during the season.

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