Sand is a critical resource for modern construction, and global demand often exceeds natural replenishment rates, leading to extensive illegal sand mining. The Vietnamese Mekong Delta, one of the largest deltas in Asia, has a long history of riverbed sand mining. This study quantifies the extent of illegal sand mining in the Mekong Delta by comparing the actual volume of sand mined with the allowable rate set by the provincial government. The volume of illegally mined sand decreased from 16.7 Mm³/yr in 2013 to 15.5 Mm³/yr in 2018-2020, partly due to an increase in the allowable rate of sand extraction from 11.5 Mm³/yr to 15.1 Mm³/yr. The study highlights the need for scientific research to assess allowable rates and sand reserves, and recommends sustainable sand mining practices to minimize environmental degradation.Sand is a critical resource for modern construction, and global demand often exceeds natural replenishment rates, leading to extensive illegal sand mining. The Vietnamese Mekong Delta, one of the largest deltas in Asia, has a long history of riverbed sand mining. This study quantifies the extent of illegal sand mining in the Mekong Delta by comparing the actual volume of sand mined with the allowable rate set by the provincial government. The volume of illegally mined sand decreased from 16.7 Mm³/yr in 2013 to 15.5 Mm³/yr in 2018-2020, partly due to an increase in the allowable rate of sand extraction from 11.5 Mm³/yr to 15.1 Mm³/yr. The study highlights the need for scientific research to assess allowable rates and sand reserves, and recommends sustainable sand mining practices to minimize environmental degradation.