LakeWatch Summary 2018

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In 2018, ALMS received funding from the Lakeland Industry and Community Association (LICA), theRed Deer River Watershed Alliance, the Pigeon Lake Watershed Association, the MD of Wainwright,Jackfish Lake Management Association and Alberta Environment and Parks, to conduct LakeWatch, a volunteer based water quality monitoring program. Data presented below has not completed its final validation process.

Volunteers

In 2018, ALMS worked with 94 unique volunteers for a total of625 volunteer hours spent sampling lakes. Each year, ALMS recognizesone volunteer who has shown outstanding dedication and commitment to theLakeWatch program. This year, Anto Davis of Lacombe Lake was presented with the LakeWatch Volunteer of the Year Award.

*LakeWatchVolunteer of the Year (2018) recipient Anto Davis during a sampling trip on Lacombe Lake.*

Sample Record

Three summer field technicians (Alanna Roberts, Lindsay Boucher and Shona Derlukewich) were hired in May of 2018 to conduct water quality sampling. ALMS completed a provincial park monitoring program at five lakes and a standard monitoring program at 27 lakes. From June through early October 2018, lakes were visited four or five times each. In 2018, 142 of 149 scheduled trips were completed. This resulted in a completion rate of 95.1% (Table 1). Missed trips were a result of volunteer availability, one boat mechanical issue, and unsafe weather.

Table 1- The LakeWatch sample completion record for 2018.

Results

While ALMS collects a large suite of water chemistry parameters, this report will highlight the variability which exists across only a few of our major parameters: Secchi Depth, Total Phosphorus, Chlorophyll-a, and Microcystin. The variation within these parameters does not necessarily reflect a degree of lake management, for many factors outside of human control also impact lake water quality. The depth of the lake, the size of the drainage basin, lake order, and the composition of bedrock and sediment are just some of the factors which affect lake water quality and should be taken into consideration when reading these results.

Water Clarity and Secchi Depth

Water clarity is influenced by suspended materials both living and dead,as well as dissolved colored compounds in the water column. During the melting of snow and ice in spring, lake water can become turbid (cloudy) from silt transported into the lake. Lake water usually clears in late spring but then becomes more turbid with increased algal growth as the summer progresses. The easiest and most widely used measure of lake water clarity is the Secchi disk depth. Two times the Secchi disk depth equals the euphotic depth – the depth to which there is enough light for photosynthesis.

Average Secchi depths in 2018 ranged from a minimum of 0.38 m at Half Moon Lake to a maximum of 4.98 m at Burnstick Lake (Figure 1). Water clarity at Half Moon,Little Beaver, Blackfalds and Saskatoon Lakes appears to be negatively impacted by algal blooms, and Secchi depth averages were significantly negatively correlated with average chlorophyll-a concentrations across lakes (Kendalls’ Tau-b, τ_b= -0.51, p-value < 0.001).

Figure 2: Average Secchi disk depth (m) values measured at 32 LakeWatch lakes during the summer of 2018.

Water Chemistry

ALMS measures a suite of water chemistry parameters. Phosphorus, nitrogen, and chlorophyll-a are important because they are indicators of eutrophication, or excess nutrients, which can lead to harmful algal/cyano bacteria blooms. One direct measure of harmful cyanobacteria blooms are Microcystins, a common group of toxins produced by cyanobacteria.

Average total phosphorus concentrations ranged from a minimum of 1.2 µg/L at Clear Lake to a maximum of 1050 µg/L at Jessie Lake (Figure 3).

Figure 3: Average total phosphorus (TP) concentrations measured at 32 LakeWatch lakes during the summer of 2018.

Chlorophyll-a

Chlorophyll-a is the green pigment found in plants and algae’s that allows them to photosynthesize. Measuring the concentration of chlorophyll-a is a common way of testing how much algae is present in lake water, because any green algae will contain it.

Average chlorophyll-a concentrations ranged from a minimum of 2.82 μg /L at Burnstick Lake to a maximum of 197 μg /Lat Little Beaver Lake (Figure 4).

Chlorophyll-a and TP averages were significantly correlated across lakes (Kendalls’ Tau, τ= 0.64,p-value < 0.001).

Figure 4: Average chlorophyll-a values measured at 32 LakeWatch lakes during the summer of 2018.

Microcystin

Microcystins are toxins produced by cyanobacteria (blue-green algae) which, when ingested, can cause severe liver damage. Microcystins are produced by many species of cyanobacteria which are common to Alberta’s Lakes, and are thought to be the one of the most common cyano bacteria toxins. In Alberta, recreational guidelines for microcystin are set at 20 µg/L.

Average microcystin concentrations fell below the minimum detection limit of 0.1 μg/L at Long Island Lake (Figure 5). Microcystin was detected at every other lake, with the highest average concentration observed at Little Beaver Lake, measuring 14.5 μg /L.None of the lakes sampled measured higher than the recreational guideline of 20μg /L at any time throughout the summer of 2018. However, samples from individual locations may display toxin concentrations higher than the recreational guidelines, and caution should be observed when recreating in or around cyanobacteria.