This post is my first as a Tucson, Arizona resident, and I started writing it on an unusual day (for Arizona) when it was raining furiously.  Our furniture had not yet arrived, so I sat in an empty house with a laptop and a lot of time to think.

The Sonoran Desert features a lot of occasional streams.  Most of the year these streams have dry beds (called “washes”) and they are only different from the surrounding desert by being lower and a bit more pebbly.  Tucson’s public works agencies have constructed some truly massive concrete channels to contain the bigger washes.  The city streets go around and over the concrete channels, and neighorhoods are separated by them.  My parents live near a large wash on “Shoreline Drive”, a name that seems ridiculous in the dryer seasons.

Tanque Verde Wash, right after a heavy rain

Like natural slot canyons, washes can go from completely dry to violently flowing in very little time, sometimes when it’s raining upstream and not where you happen to be.  The nearby mountains are thousands of feet tall, and when there is water it travels fast.  Tucson has built a number of walking and bicycle paths along the edges of some of the main washes, and they are usually pleasant places to exercise.

Out for a walk on the pedestrian path

The less built-up parts of town (either older, further from the center, or both) have “arroyos”, which are natural or slightly assisted ditches that contain streams smaller than the concrete washes.  Sometimes the arroyos cross the road in a dip, and there are signs reading “do not enter when flooded”.  In a serious rain, such roads are impassable, and you just need to wait.  Marcy lived here many years ago, and she tells a story about arriving an hour late for a dinner on a rainy day, because she had to wait for an arroyo to reduce its flow.

One of the “old style” road crossings, Agua Caliente Wash has no concrete channel and bridge.

When the recent rain finished, the washes were very full and looked like legitimate rivers.  After a few days, they emptied out again and became modest trickles or even completely dry.

Pantano Wash, after just one day of drying up

We hiked in Saguaro National Park and found no water in the secondary streams, but one more major stream had a nice flow.  A few isolated depressions had puddles of standing water, but basically the desert was returning to its usual arid state.

No water in this tributary stream, about a week after the rain…
…but the main stream was still slightly flowing.

The taller mountains got a nice snowcap. The vegetation turned a bit more green and the saguaro cacti bulked up to hold the additional moisture.