Range of water harvesting definitions, techniques, designs, etc. Information can generally be used in multiple areas in the Southwest US, even though the following are listed by geographic area:
EPA Rainwater Harvesting Manual, Municipal Handbook http://wrrc.arizona.edu/sites/wrrc.arizona.edu/files/EPA_gi_munichandbook_harvesting.pdf
Drylands in general at http://www.harvestingrainwater.com/rainwater-harvesting-inforesources/
Arizona http://wrrc.arizona.edu/publications/water-harvesting/city-tucson-water-harvesting-guidance-manual and http://wrrc.arizona.edu/publications/water-harvesting/harvesting-rainwater-landscape-use
Texas http://wrrc.arizona.edu/sites/wrrc.arizona.edu/files/TWDB_The%20Texas%20Manual%20on%20RWH.pdf
New Mexico http://wrrc.arizona.edu/sites/wrrc.arizona.edu/files/SSCAFCA_Rainwater%20Harvesting.pdf
California http://wrrc.arizona.edu/sites/wrrc.arizona.edu/files/COSD_Rainwater%20Harvesting%20Guide.pdf