Most of the part of Udaipur Jheel falls within the Udaipur Wildlife Sanctuary (26.812952o N, 84.431371o E) in the West Champaran district. The wetland is an oxbow lake formed in the floodplains of the Gandak River. The wetland covers an area of 319.70 ha. The wetland forms a refuge to diverse flora and fauna. Due to high bird diversity the wetland has been recognized as an Important Bird Area (IBA). It provides habitat for 26 waterbird species (AWC 2024). 41 species of Zooplanktons, 13 species of Benthic macro-invertebrates, 29 fish species and five mammalian species have also been recorded from the wetland (Sinha and Kedia 2015). ~ 3000 members of local communities of villages Majharia, Patrakha-Naurangia, Balua-Rampurva, Tumkuria, Siswa Saria, Bhataul, Harhi Nala and Sirsia-Mathia are benefitted by the several ecosystem services provided by the wetland. The wetland is also a potential tourism site in the state. The peripheral areas of the sanctuary are anthropogenically controlled. Sporadic incidences of illegal fishing and intensive agricultural activities with frequent use of chemical fertilizers and pesticides in the adjoining areas are the major threats reported. A canal that joins the wetland and the Gandak River serves as an inlet. This inlet has choked and is being cleaned to maintain the hydrological regime of the wetland. The management of the wetland falls under the jurisdiction of the Bettiah Forest Division. A Sanctuary Management Plan is being implemented.

A wetland should be considered internationally important if it contains a representative, rare, or unique example of a natural or near-natural wetland type found within the appropriate biogeographic region.

A wetland should be considered internationally important if it supports vulnerable, endangered, or critically endangered species or threatened ecological communities.

A wetland should be considered internationally important if it supports populations of plant and/or animal species important for maintaining the biological diversity of a particular biogeographic region.

A wetland should be considered internationally important if it supports plant and/or animal species at a critical stage in their life cycles, or provides refuge during adverse conditions.

A wetland should be considered internationally important if it regularly supports 20,000 or more waterbirds.

A wetland should be considered internationally important if it regularly supports 1% of the individuals in a population of one species or subspecies of waterbird.

A wetland should be considered internationally important if it supports a significant proportion of indigenous fish subspecies, species or families, life-history stages, species interactions and/or populations that are representative of wetland benefits and/or values and thereby contributes to global biological diversity.

A wetland should be considered internationally important if it is an important source of food for fishes, spawning ground, nursery and/or migration path on which fish stocks, either within the wetland or elsewhere, depend.

A wetland should be considered internationally important if it regularly supports 1% of the individuals in a population of one species or subspecies of wetland-dependent nonavian animal species.