Water Rangers measures dissolved oxygen, or DO2, in milligrams/litre. Different measurements of DO2 will mean different circumstances for life in a water body, shown below;
0-2 mg/L: not enough oxygen to support life
2-4 mg/L: only a few fish and aquatic insects can survive
4-7 mg/L: good for many aquatic animals, low for cold water fish
7-11 mg/L: very good for most stream fish
For more an introduction, our protocol, and additional information regarding dissolved oxygen, we encourage you to visit our dissolved oxygen parameter page!