Groundwater contribution to Sylvan Lake, Alberta, Canada

The trophic status and concentration of total dissolved solids in Sylvan Lake, Alberta, Canada, are relatively low and may be indicative of groundwater through-flow in the lake. Investigation of water well drilling records around Sylvan Lake suggests that a fractured water-bearing channel sandstone runs along the northeast margin of Sylvan Lake and sits in a matrix of shale with small sandy interbeds. Three separate mass-balances (chloride, deuterium and oxygen-18) suggest that groundwater fluxes into and out of the lake are 27 to 35% of total annual lake water inputs, and significant with respect to the lake water chemistry, resulting in an average lake-water residence time of 20 to 35 years. Groundwater through-flow is likely partly responsible for the relatively low trophic status of Sylvan Lake as compared to other lakes in south-central Alberta and is thought to occur in the hydraulically connected channel sandstone aquifer of the Paskapoo Formation. Due to the hydraulic connection of the sandstone channel with Sylvan Lake, development along the north side of the lake (above the channel) may have more significant impacts on the lake water quality than development elsewhere around the lake.