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Wednesday, July 17, 2019

Oxygen levels cause of fish die-off at City Park Lake

Following a fish kill observed in City Park Lake on June 20, Westminster’s contracted lake management firm completed an analysis to determine the cause of the event. That study indicated that the fish kill was likely caused by low levels of dissolved oxygen.

Although fish live in water, they still need oxygen dissolved in the water to survive. Nutrients, specifically nitrogen and phosphorus, had accumulated in the lake and caused an algae bloom that depleted the oxygen available to the fish population. These algae produce oxygen, but under certain conditions (for example, when too many algae are present, or there is a long stretch of cloudy days), the algae begins to die. Bacteria then decompose this algae and consume oxygen in the process, leading to a lack of oxygen in the water.

The accumulated nutrients likely came from a variety of sources including stormwater runoff, fertilizers, and parking lot and road chemicals. The existing aeration system was not sufficient to keep up with the high oxygen demand in the lake.

The City of Westminster strives to provide the highest quality parks and open space for our community and wildlife. 

Based on conversations with the state, the city will be working to maintain the water quality of the lake for aesthetic purposes only. Therefore, the lake will be returned to its original intention as an impoundment for irrigation. Fish stocking and fishing will no longer be allowed at City Park Lake, indefinitely.

Young fishing enthusiasts are encouraged to attend the Fishing Frenzy program on Saturday, Aug. 3, at Kensington Park/Ketner Reservoir.

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