Official websites use .gov
A .gov website belongs to an official government organization in the United States.
Secure .gov websites use HTTPS
A lock () or https:// means you’ve safely connected to the .gov website. Share sensitive information only on official, secure websites.
Visual representation of the range of turbidities tested (0–1,000) formazin nephlometric units in the 2013 laboratory experiment. The source of this turbidity is silt collected from Grand Falls, Little Colorado River, Arizona.
