Just 200 feet to the south of my house is a medium sized wash that runs east-west. It bisects the street I live on so that cars can't drive past my house and down to the houses further south. Even though the road doesn't proceed over the wash we find it no problem to walk across it almost daily. It looks a lot like a dry creek bed. Crusty mud and sand line the bed with river rocks and small boulders sprawled throughout the channel. On occasion, after a heavy rain, I'll see a small trickle of water in the wash. Not really enough to even flow but enough to prove that water does actually make it into the wash every now and then. However, recently Phoenix weathered a very severe rainstorm. I've seen heavy rain before but nothing quite this heavy. As always, it was fun and exciting to see such extreme weather. in this case, it was also fun to watch the wash. It actually filled with water! After seeing the amount of water flowing through it I can now understand why people tell us to stay out of washes when there is heavy rain. Below I have some pictures of the wash with water. About 2 hours before this picture the area had barely any water in it.

In many places the water in the wash probably only got about two feet deep.  Growing up I would frequently walk through streams and creeks with two feet of water.  Even streams that were flowing swiftly like the wash was flowing that day. But the water level and velocity aren't the only danger with washes.  The water flowing through them is runoff from the surrounding desert.  The runoff is full of spiders, scorpions, and snakes that have been washed out of their homes.  Stepping your leg into this stream is just an invitation for a scorpion to find something to latch onto to get out of the water.  In an emergency I'd probably cross a full wash but generally speaking I'd avoid getting in it.

Here are the pictures I took.