Where the rain in Phoenix, Arizona flows to
Even though Phoenix is in the desert, a lot of water flows through it. There are always summer thunderstorms, and in the winter what I like to call "Christmas rains", which are usually more gentle. And then in the spring the snow melts in the uplifted areas northeast of Phoenix and flows down to the valley through the Salt River, the Verde, and hundreds of other rivers and washes. Controlling the flooding in the valley has been a problem since the days of the Hohokams, and continues to be a challenge to the engineers of Phoenix. And although the storm drains don't say "flows to the ocean" like they do in LA, the water does. It flows to the Gulf of California. This is how it flows, starting with my little house in suburban Glendale when it rains.
When the rain begins, and starts to water my petunias, after a little while it puddles in my backyard. Then it flows along the side of my house and drains out to the front into the street. The Salt River Valley, from north Scottsdale to Goodyear, tilts from northeast to southwest. So all of the water flows downhill towards a place called "Tres Rios" (Spanish for Three Rivers), which is the convergence of the Agua Fria, the Salt, and the Gila (which flows from the south).
Tres Rios is a wetlands, and also a sewage water treatment plant. From there, the water that started in my backyard in Glendale flows down the Gila River towards Yuma, where it empties out at the mouth of the Colorado River at the Gulf of California, and then on to the Pacific Ocean.
Of course when the snow melts in the watershed northeast of Phoenix, much of the water is caught in reservoirs along the Salt River, the largest of which is the Roosevelt Dam, which has been there since 1911. When there is too much water for the dams to hold (and there are seven on the Salt River), it's released down into the normally-dry riverbed of the Salt River south of the airport. When I went to ASU, I remember that it knocked down most of the bridges. I grew up in Minneapolis, and I always thought that it was kind of strange that the bridges in the Phoenix area only worked when there wasn't any water flowing under them. But I didn't know about the enormous force of the water being released.
If you're new to Phoenix, or you hadn't given it much thought before, it might seem surprising that controlling floodwater is such a big concern for a desert city. I know that it surprised me when I found out about it, and it continues to fascinate me. Thank you, Maricopa County Flood Control District!
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Posted by Brad Hall