A case was presented where a lake had high organic matter input, high dissolved organic carbon and low dissolved oxygen concentrations. The goal of managing the pond was to improve water quality conditions for the trout population in the lake.
Upon first sampling, it was found that the average max depth where dissolved oxygen concentrations were viable for trout was 1.8 m (6 ft) whereas the average depth was around 4 m (13 ft). Because trout need relatively cold water to survive, the upper layers of the pond might pass the trout’s temperature threshold for survival in summer. Normally, trout move into the deeper water during these times, however, lack of oxygen could leave the trout with a very small habitat range and could easily lead to extirpation of the population.
Dissolved oxygen significantly improved from before and after treatment in all sampled stations. The greatest improvement was seen at the deepest points with the average dissolved oxygen going from essentially 0 mg/L to around 5 mg/L which is above the DO concentration needed for trout survival. The treatment expanded the habitat of the trout by 55% to include the entire pond.