Webster Lake covers an area of 606 acres and has a maximum depth of 39 feet. The lake is fed by Sucker Brook and drains into Chance Pond Brook, which eventually joins the Pemigewasset River. The Pemigewasset River merges with the Winnipesaukee River to form the Merrimack River, which flows south to Massachusetts. Webster Lake has two public beaches operated by the city of Franklin, and a boat launch near Lagace Beach on NH-11. There is shoreline access at two locations on the east side of the lake.