Jagdishpur Reservoir, located in Nepal, stands as the nation's largest reservoir with a surface area of 225 hectares. Established primarily for irrigation purposes, it was constructed over the site of the former Jakhira Lake and surrounding agricultural land in the early 1970s. The reservoir's water is sourced from the nearby Banganga River, which originates in the Churia Hills. The water depth in the reservoir varies, with the deepest point ranging from 5 to 7 meters and the shallowest areas measuring between 2 to 3 meters.
The reservoir is encircled by cultivated lands, and in its vicinity lie two smaller lakes, Sagarhawa and Niglihawa, which act as buffer habitats for bird movements. The banks of the reservoir are adorned with trees like Dalbergia sissoo and Acacia catechu. The aquatic vegetation is characterized by extensive coverage of floating leaved species, predominantly Nelumbo nucifera, accompanied by Hygrorhiza aristata and Potamogetan nodosus. Submerged species such as Naja minor, Ceratophyllum demersum, and Hydrilla verticillata are also abundant. Plants like Ipomea carnea ssp. fistulosa and Typha angustifolia thrive around the reservoir's margin.
The reservoir's vegetation is in a submerged succession stage, interspersed with patches of floating species and reed swamp formations. The dense aquatic macrophyte vegetation indicates an advancing eutrophic status and a high sedimentation rate. This could potentially lead to a rapid transition towards a marsh meadow condition, thereby reducing the reservoir's lifespan if a desiltation tank is not introduced.
From an ornithological perspective, Jagdishpur Reservoir is of significant importance. Although the bird species of Jagdishpur are not extensively documented, the site is believed to be a vital habitat for resident, wintering, and passage migrant wetland birds. Notably, five globally threatened species, including the Lesser Adjutant, have been recorded. A survey in July 1997 identified 42 bird species, but comprehensive studies are yet to be conducted. The reservoir also supports the globally threatened Smooth-coated Otter (Lutrogale perspicillata) and is home to 25 species of fish.
This reservoir underscores the rich biodiversity of Nepal and serves as a testament to the nation's commitment to preserving its natural habitats.