Loveland Reservoir is a man-made reservoir located in California's Cuyamaca Mountains. It was constructed in 1946 and is owned by the City of San Diego. The reservoir has a capacity of 25,500 acre-feet and is fed by the Sweetwater River. It primarily serves as a storage facility for the city's water supply.

The hydrology of Loveland Reservoir is dependent on both surface flow and snowpack providers, with the Sweetwater River being the primary surface flow provider. The reservoir also receives water from the Cuyamaca Mountains snowpack during the winter months.

While Loveland Reservoir is primarily used for water storage, it also supports agricultural and recreational activities in the surrounding area. The water is used for irrigation of crops and provides a source of fishing and boating for visitors. The reservoir is popular for hiking and camping and offers scenic views of the surrounding mountains.