Lake Mosier (Fostoria Reservoir 4) is one of Fostoria’s six upground reservoirs, built as part of the city’s water‑supply system and later developed as a key fishing and recreation area.

Name origin

Lake Mosier is named in honor of a local Fostoria serviceman with the Mosier surname who was killed in World War II, part of a broader decision to dedicate the city’s reservoirs to fallen veterans. In 1946, the four main reservoirs then in service were each given the name of the first Fostoria veteran in their branch of the armed forces who died in the war, and Reservoir 4 was designated “Lake Mosier” to commemorate that individual sacrifice.

Origins and purpose

Lake Mosier—also known as Reservoir 4—is an upground reservoir on the southwest side of Fostoria, supplied, like the other city reservoirs, by pumping from the East Branch of the Portage River. Fostoria’s reservoir system was built out across the 1900s to provide a reliable municipal water source, using man‑made storage basins instead of relying solely on wells or natural lakes.

Physical features and recreation

Lake Mosier covers about 91 acres of water and roughly 160 acres of surrounding land, making it one of the medium‑sized basins in the chain. It has supported fishing, small‑boat use, and birding, with about 1.5 miles of stone trail around the water and shorelines that attract waterfowl and shorebirds during migration.

Role in the reservoir system and recent changes

Fostoria now uses six upground reservoirs totaling over 450 acres of water and 700 acres of land, with Reservoirs 1–5 (including Lake Mosier) named after individual war heroes and Reservoir 6 dedicated to all veterans as Veterans Memorial Reservoir. Recent city plans call for converting Reservoir 4/Lake Mosier into a wetlands‑style recreational area, shifting it from a traditional storage basin toward more habitat, wildlife, and low‑impact public use while other reservoirs continue to carry most of the water‑supply role.