Lesser Slave Lake is the third largest lake in the province and is the central feature of the watershed. The watershed supports strong agricultural, forestry, and oil and
gas industries, and is a tourist destination for people who are drawn to the lake for the abundant recreation and sportfishing opportunities. The lake’s name refers to the original
inhabitants of the land near the lake, the Slavey people. In more recent times, the lakeshore was and continues to be inhabited by the Cree people, and then later on, by fur traders who set up fur trading posts throughout the lake’s watershed and settlers soon followed. 

The main sport fish are northern pike (Esox lucius), yellow perch (Perca flavescens), walleye (Sander vitreus), burbot (Lota lota), and lake whitefish (Coregonus clupeaformis). Lake trout used to be abundant in the lake, but were extirpated from the lake in the early 1990s.
Lesser Slave Lake has a large drainage basin covering an area of 12,400km2 mostly to the south, west, and northwest of the lake. The main outlet, the Lesser Slave River, flows from the southeast end of the lake to the Athabasca River, approximately 70 km downstream. Lesser Slave Lake has a surface area of 1,160 km2, with a moderate maximum depth of 20.5m in the centre of the east basin, and an average depth of 11.4m. Lesser Slave Lake is considered a eutrophic lake, meaning it is naturally high in nutrients. 

Lake Water Quality 

Due to the large size of Lesser Slave Lake, the water quality does not see rapid seasonal or annual changes like smaller lakes in central Alberta. The government of Alberta has been tracking lake levels and monitoring lake water quality since the 1940's. 
Here are some historic water quality reports published by the Government of Alberta: 

Lesser Slave Lake - Results of Water Quality Survey Conducted by Alberta Environment in 2000-2002


In the summer of 2021 Alberta Environment and Protected Areas staff collected samples and took field measurements at locations in the east and west basins of Lesser Slave Lake. The LSWC receives many requests for lake water quality information from stakeholders and the public, so we asked our partners at the Alberta Lake Management Society to prepare a Lakewatch report for LSL based on the 2021 water quality data.  The report can be downloaded HERE. 


Monitoring Partnerships

Winter Lake Keepers with ALMS 
  Aquatic Invasive Species Monitoring with Environment and Protected Areas