Environmental Impact Assessment of Sand Mining Operations on the Niger River, Niger State

Unregulated sand mining from the Niger River in Niger State, North Central Nigeria, has generated extensive channel degradation, bank erosion, and habitat destruction that threaten downstream water supply infrastructure and the livelihoods of riparian communities. This study conducts an environmental impact assessment of sand mining operations on a forty-kilometre reach of the Niger River in Niger State, evaluating changes in channel morphology, sediment dynamics, water quality, and ecological condition. Repeat bathymetric surveys at pre-defined cross-sections were conducted six months apart to quantify volumetric changes in river bed elevation attributable to dredging. Bank erosion rates were measured by erosion pins and compared with historical channel boundaries digitised from Google Earth imagery spanning the period 2005 to 2023. Water quality sampling assessed turbidity, total suspended solids, dissolved oxygen, and heavy metal concentrations at upstream and downstream stations relative to active dredging areas. Benthic macroinvertebrate sampling provided ecological condition indices for contamination assessment. The study evaluates compliance of active operators with the Environmental Impact Assessment Act and the National Environmental Standards and Regulations Enforcement Agency guidelines. A mitigation framework specifying setback zones, minimum channel maintenance depths, and restoration obligations is recommended for adoption by the Niger State Ministry of Environment. Keywords: sand mining, environmental impact, Niger River, channel morphology, Niger State.