From and Mr. Grantham’s presentation – The focus of environmental flows addresses the fundamental question of how much water does a river need and how can our surface water systems, our rivers, streams, and lakes be managed in ways that preserve the volume of water that’s really needed to sustain healthy ecosystems while also meeting human demands.  This is a question that has risen to the attention of the scientific community over the past 20 or 30 years. (more).