Over the past two weeks, residents of Columbia Lake have raised concerns about the recent accumulation of dead fish observed on Columbia Lake and along its shoreline.

Several potential causes can result in fish kills, with one of the principal causes being a lack of dissolved oxygen (DO) in lake water, reported the Columbia Lake Stewardship Society (CLSS) in a social media post.

“Oxygen in water is measured by the level of dissolved oxygen (DO). Cold water can hold more oxygen than warmer water. As water temperatures rise, the amount of dissolved oxygen decreases. The depleted DO levels can become insufficient to support fish, causing them to die. Additionally, the decomposition of organic matter, which can increase as water temperatures rise, further decreases the oxygen available to fish,” CLSS outlined.

The Columbia Lake Stewardship Society has been monitoring the lake since 2014, collecting data on parameters such as temperature, conductivity, pH, turbidity, and DO. This long-term data helps us understand ecological changes over time.

“Our recent data reveals that July 15, 2024, marks the highest temperature recorded in our database since we began monitoring Columbia Lake in 2014. The average temperature taken at four sites across Columbia Lake between 10:20 a.m. and 11:50 a.m. was 24.4°C, likely reaching higher temperatures later in the day.

“Healthy concentrations of dissolved oxygen in water are typically above 6.5 – eight mg/L. Dissolved oxygen concentrations measured on July 15 appear to be within a normal range, averaging 9.29 mg/L. However, these concentrations can fluctuate within a 24-hour period and can be affected by the time of day and location of our monitoring.

“We cannot pinpoint the exact cause of the recent fish deaths in Columbia Lake, but we presume that the high temperatures and the potential reduction in dissolved oxygen concentrations were likely significant factors,” CLSS concluded.

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