LLP: Phosphorus, Calcium, Chloride, and Clarity

The Ontario Lake Partner Program is a province-wide, volunteer-based, water-quality monitoring program administered by the Ministry of Environment, Conservation and Parks.  Volunteers collect samples and submit them for analysis by the MOE.  The results can be found at https://foca.on.ca/lake-partner-program/  

TOTAL PHOSPHORUS

Phosphorus is the element that controls the growth of algae in most Ontario lakes. It is naturally found in the water and in the bottom mud.  But increased levels can result from runoff from the shore, primarily from the use of household chemicals or lawn fertilizers.  Increases in phosphorus can decrease water clarity by stimulating algal growth, which in turn can cause decreases in oxygen levels.  Lakes with Total Phosphorus of less than 10 mcg/L are considered low-nutrient lakes with lesser risk of algal blooms.

The results indicate that Loon Lake can be considered a low-nutrient lake, with Total Phosphorus levels well below the concentrations that would support algal blooms.

CALCIUM

Calcium levels in lake water can be diminished by acid rain.  Calcium is an important nutrient for many organisms, including Daphnia (waterfleas), which struggle when levels drop below 1.5 mg/L. 

The results indicate that Loon Lake can be considered to have healthy concentrations of calcium.

CHLORIDE

It is very important that we monitor chloride levels because of Highway 118, which forms a 1.6-km border across the north end of Loon Lake.  Runoff of rainwater and snow melt is conducted directly into the lake. Calcium levels of 120 mg/L or more can have an adverse effect on aquatic life.

The results indicate that chloride levels in Loon Lake do not pose a threat to aquatic organisms.

WATER CLARITY

A Secchi disc is used to test water clarity in the lake.The secchi disc has alternating black and white sectors to increase its visibility under water.  The depth at which it is no longer visible is recorded.

Water clarity can be affected in many ways, and interpretation of the results can be difficult. The main objective is to look at trends and watch for sudden changes in Secchi depths.

Secchi depths in Loon Lake have been very consistent, ranging from 4 to 6 meters since 1998.