Guwahati: A Nagaland University study has sounded an environmental alert for Loktak Lake, one of India’s most iconic freshwater ecosystems and a designated ‘Ramsar Site’ in Manipur.
Researchers found that changes in land use — particularly agriculture, settlements, and shifting cultivation — are directly deteriorating the water quality of rivers feeding into the lake, threatening its biodiversity and the livelihoods of local communities.
Loktak Lake is home to 132 plant species and 428 animal species, and supports hydropower, fisheries, transport, and tourism. However, in recent decades, the lake has been listed under the Montreux Record, a global warning list for wetlands undergoing serious ecological damage. Reduced fish populations, rising pollution levels and increased sedimentation have now become growing concerns.
A Ramsar site is a wetland designated to be of international importance under Ramsar Convention on Wetlands. These sites are recognised for their ecological significance, such as supporting biodiversity or providing critical habitat for waterfowl. The convention was signed in 1971 in Ramsar, Iran.
The study was undertaken by Dr. Eliza Khwairakpam of Nagaland University. The findings were published in the International Journal of Environment and Pollution, a peer-reviewed journal publishing research on environmental contaminants and their impact on health and ecosystems.
Highlighting the need for such studies, Prof. Jagadish K Patnaik, Vice Chancellor, Nagaland University said, “Nagaland University takes great pride in the significant research contribution made by our faculty and scholars, revealing the strong link between land use and water pollution in the Loktak Lake catchment area of Manipur”.
Patnaik said that this study highlights the pressing environmental challenges arising from agricultural runoff, human settlements, and shifting cultivation, which are directly impacting the river water quality in the region.
“Nagaland University remains committed to promoting research-driven environmental stewardship that informs policy, fosters sustainable livelihoods, and safeguards our natural ecosystems,” he added.
To understand the root cause, Nagaland University researchers conducted field sampling across nine major rivers — Khuga, Western, Nambul, Imphal, Kongba, Iril, Thoubal, Heirok and Sekmai — that drain into Loktak Lake.
Using detailed Land Use Land Cover (LULC) maps, Dr. Eliza Khwairakpam compared different types of land activities such as agricultural areas, dense and degraded forests, settlements, Jhum cultivation and water bodies, against water quality indicators like dissolved oxygen (DO), biological oxygen demand (BOD) and temperature.
Elaborating on the key findings, Dr. Eliza Khwairakpam, Assistant Professor, Department of Environmental Science, Nagaland University, said, “Our study confirms that land use decisions across villages and forest landscapes upstream are directly impacting water quality downstream. This makes community-based land management and stricter control of agricultural runoff and waste discharge crucial for restoring Loktak Lake.”
Further, Dr. Eliza Khwairakpam added, “Land management is not just an environmental concern but a livelihood protection strategy for the people of Manipur. Catchment-wide land regulation, sustainable agriculture practices and controlled Jhum cycles will be vital for protecting India’s only floating national park and the endangered Sangai deer habitat within the lake.”
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The Nambul River was identified as the most polluted, with low oxygen levels and high organic contamination, directly linked to 47% agricultural land and 11% settlement areas in its sub-catchment. The Khuga River showed the second poorest water quality, despite having higher forest cover. Researchers attribute this to extensive Jhum (shifting) cultivation, which was recorded at 42% in the region.
In contrast, rivers such as Iril and Thoubal, which flowed through greater forest-dominated landscapes, displayed better water quality, highlighting the protective role of natural vegetation.
The research was supported by the Forest Department, Government of Manipur, which provided LULC maps, and the Manipur Pollution Control Board for field assistance. The study was jointly supported by Nagaland University and IIT Delhi.
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