An official website of the United States government
Official websites use .gov
A .gov website belongs to an official government organization in the United States.
Secure .gov websites use HTTPS
A lock (
LockA locked padlock
) or https:// means you’ve safely connected to the .gov website. Share sensitive information only on official, secure websites.
Image Number K10030-1
Oxygen probe used to evaluate the effect of wetland vegetation on water quality.
Photo by Peggy Greb.
640 pixels wide: (k10030-1.jpg)