Researchers have completed a full accounting of water uses and losses in the Rio Grande-Bravo basin as it faces severe shortages throughout its range in the United States and Mexico. The findings released Thursday by the World Wildlife Fund, Sustainable Waters and a team of university researchers show unsustainable use threatens water security for millions of people who rely on the binational basin. They estimate that just 48% of water consumed throughout the basin is replenished by renewable sources like snowmelt and rain. The rest is unsustainable, meaning reservoirs, aquifers and river flows are further depleted. The report says urgent action is needed to avoid damaging consequences for farms, cities and ecosystems.