The results from the Area Threshold Network tool will provide the domain of features from which you will choose to assign stream reaches.

Follow these steps to identify which features to use as stream reaches:

Start by selecting stream segments that have a Strahler stream order of at least 3 or 4 or greater.

In the Selection menu item, choose “Select by Attributes.”
Create a query for your layer (e.g., “STRAHLOrd >= 4”) and press “Apply.”
Take a look at the selection and see that the main channel has been selected, as well as some of the larger branches.
In the StreamType field, right-click and go to the Field Calculator and assign these a value of 1.
Press “OK.”

Once you have started this process, you can visit individual segments and decide if they should be included in the collection for stream reaches. If they should be, select the features visually, and use the Field Calculator to assign these a StreamType value of 1. Continue reviewing different areas of the map and deciding which segments to select as stream reaches and code to StreamType = 1.