Abstract
Many water bodies in western Canada experience high internal phosphorus recycling rates and excessive primary production, with associated water column anoxia and restricted fisheries habitat. Lime (Ca(OH)2 and CaCO3) application and hypolimnetic oxygenation were investigated in Alberta as nontoxic, inexpensive management alternatives. In hardwater lakes, multiple Ca(OH)2 applications at dosages <100 mg L-1 reduced chl a and TP concentrations by up to ~30 and 50%, respectively, often for several years. In contrast, high flushing rates in stormwater retention basins made repeated Ca(OH)2 treatment necessary. Hypolimnetic oxygenation in Amisk Lake from 1988-93 increased hypolimnetic dissolved oxygen concentrations from 0.9 to 4.6 mgL-1 in the treated basin while maintaining thermal stratification. Epilimnetic whole-lake chl a and TP concentrations were reduced by 55 and 13%, respectively. Deep-water habitat was improved for fish, zooplankton and macroinvertebrates. Our research shows that water quality can be improved in lakes that are naturally eutrophic (i.e., due to internal P cycling) and has implications for lake management projects worldwide.
Characterizing near-surface karst system under three stormwater retention basins in Silver Springs, Florida