Laguna Lake, lake and seasonal reservoir in San Luis Obispo, California, United States

Laguna Lake is a lake and seasonal reservoir in the upper Los Osos Valley within San Luis Obispo, California, at an elevation of 121 feet (37 m). It is fed and drained by Prefumo Creek, a tributary of San Luis Obispo Creek: the creek enters at the west end and leaves at the eastern end. The reservoir covers about 0.53 square kilometres.

The land surrounding the lake was once part of Rancho Laguna, a large farm belonging to Mission San Luis Obispo used for farming and grazing long ago. Today it functions as a storage reservoir, managing water during dry seasons to supply local farms and neighborhoods.

The lake lies within the former Rancho Laguna, a section of Mission San Luis Obispo lands that originally enclosed the water. Prefumo Creek enters at the western end and drains the lake at its eastern end, flowing on to San Luis Obispo Creek.

Laguna Lake lies in the upper Los Osos Valley, reached from San Luis Obispo via Prefumo Creek, which enters at the west end and drains the lake at its eastern end. The reservoir covers about 0.53 square kilometres and stretches roughly 1.2 km north to south and 1.4 km east to west. Prefumo Canyon opens nearby, and Mine Hill rises about 3 km to the northeast.

The lake drains through Prefumo Creek at its eastern end, which flows into San Luis Obispo Creek. Prefumo Canyon, a valley, lies nearby. The reservoir covers about 0.53 square kilometres, and Mine Hill rises 355 metres about 3 km to the northeast.