ABSTRACT
A simple evaluation of surface waters available for regional, national or transboundary use can be based on the total river water discharge. The Colorado River, USA is an example where extraction of water has virtually depleted the final discharge to the ocean. The flow has been used almost completely by negotiated extraction and distribution to nearby states. Any increase in extraction and use would require diversion of a similar water quantity to guarantee the minimum flow required to meet all the water demands of the region.
