Ulery RLVanMetre PCCrossfield ASWater Resources Bulletin2010-02-152010-02-151993 Julhttp://hdl.handle.net/1969.3/23599685-711In 1991 the Trinity River Basin National Water-Quality Assessment (NAWQA) was among the first 20 study units to begin investigations under full-scale program implementation. The study-unit investigations will include assessments of surface-water and ground-water quality. Initial efforts have focused on identifying water-quality issues in the basin and on the environmental factors underlying those issues. The environmental setting consists of both physical and cultural factors. Physical characteristics described include climate, geology, soils, vegetation, physiography, and hydrology. Cultural characteristics discussed include population distribution, land use and land cover, agricultural practices, water use, and reservoir operations. Major water-quality categories are identified and some of the implications of the environmental factors for water quality are presentedclimatedistributionENVIRONMENTAL SETTINGNAWQAPROGRAMreservoirriverSOILTEXASTrinity RiverVEGETATIONWATERwater qualityWATER-QUALITY ASSESSMENTJournal