Fish Pond Rehabilitation

Fishing pressure at ACA stocked ponds can exceed 2,000 h/ha in the summer months, indicating these ponds can be popular among anglers. However, some of these ponds may not be capable of supporting trout survival beyond mid-summer due to low dissolved oxygen (DO). Furthermore, these ponds will not overwinter trout. Five ponds, sampled for baseline water quality data over the past two years, had high total phosphorus concentrations, with four of five ponds being hypereutrophic: Daysland Pond (233 ± 67 µg/L), Heritage Lake (315 ± 158 µg/L), Innisfree Trout Pond (112 ± 24 µg/L), and Lamont Pond (134 ± 52 µg/L); Rainbow Park Pond was eutrophic (81 ± 28 µg/L). Alum treatment will reduce bioavailable phosphorus, thereby improving water quality and DO concentration. We used Rainbow Park Pond as an alum pilot case. Through alum dosing jar tests, we determined that a total of 25 mL (59.5g Al/litre solution) of alum per litre of pond water, split over two treatments of 12.5 mL of alum, maintained favourable water quality for fish and invertebrate survival (pH of 7.5; alkalinity of 72 mg/L) while significantly reducing total phosphorus concentration (85% reduction). We are using the five ponds to conduct a before-after-control-impact experiment to determine if alum treatment can improve overall water quality and overwintering DO concentrations.

Partnerships

Alberta Environment and Parks

Annual Summaries

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