This graph shows the average temperatures and precipitation for a thirty year period in Missoula. It is important to understand the climatic changes from month to month in a watershed. The temperature of the surrounding area can explain the some of the changes in the temperature of the water. The precipitation levels tell you on average how much water is falling on the area. This information is important for understanding when it is a good time to use water out of the stream and when is a bad time to pull water from the stream.

The annual precipitation for Montana is not as much as people often think. If you look above you can see the average precipitation for Montana. Very few places actually get a great deal of precipitation. Montanans all too often think that Montana has lots of water. In truth Montanans use most of the water. Most river basins are closed to further withdrawal.  Most water in Montana that is used by humans is used for agricultural.