The lake itself is the largest and deepest lake in Snohomish County, with an area of 1,040 acres and an average depth of 64 feet. It is fed by Lundeen, Mitchell, Kokanee, and Stitch Creeks and drained by Catherine Creek, which ultimately flows to the Pilchuck River. The small size of the surrounding watershed compared to the lake minimizes the effects of upstream pollution. This combined with an artificial aeration system allows for a generally good water quality. Much of the shoreline is heavily developed, so few wetlands exist adjacent to the lake.
Lake Stevens is located at 48°1′11″N 122°3′58″W (48.019782, -122.066089)