Swan Lake, Alberta - photo of a number of fishing boats on the lake. It is said that not far from the boat launch, the depth drops quickly to about 18 feet. Swan Lake is stocked with rainbow trout annually. Rainbow Trout up to 10 pounds can be caught. Best fishing is May and June as the water is clear. From July to September, the lake is usually filled with algae. A lot of fly fishermen like to come here.