The Lower Peirce Reservoir (Chinese: 贝雅士蓄水池下段) is one of the oldest reservoirs in Singapore. It is located near MacRitchie Reservoir and Upper Peirce Reservoir. Previously known as Kallang River Reservoir and Peirce Reservoir, it was renamed Lower Peirce Reservoir after the creation of Upper Peirce Reservoir. It has a surface area of 6 hectares and the surrounding forest contains many trees that are over 100 years old. There is a Lower Peirce Trail, which is a 900-metre boardwalk that takes visitors through a mature secondary forest. The reservoir is the source of the Kallang River, the longest river in Singapore.