Flooding

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The flooding caused by Tropical Storm Norbert was not the first time flooding has occurred in the Phoenix Metro Area. Steve Waters, the flood warning branch manager for the Flood Control District of Maricopa County, will talk about the history of flooding in the Valley and give us a perspective on our system that handles flooding.

Ted Simons: Good evening, and welcome to "Arizona Horizon," I'm Ted Simons. Cleanup efforts continue around the Valley after yesterday's record rainfall. For an update of flooding conditions, and to put those conditions into historical perspective, we welcome Steve Waters, the flood warning branch manager for the Flood Control District of Maricopa County. Welcome to "Arizona Horizon," I'm sure you're a busy man these days.

Steve Waters: Very busy.

Ted Simons: What are we seeing around the county now?

Steve Waters: We're seeing water recede and Indian Bend Wash is almost dried out. Salt River is storing a little bit of water. Most of the channels that were doing their jobs yesterday are emptying out and getting back to normal. Unfortunately we do have more storms coming in tonight. We'll have to play it by ear but it won't be anything like yesterday.

Ted Simons: Have you seen anything like yesterday?

Steve Waters: We have seen storms like that. They don't always hit right in the urban area. In the past and in different areas of the county we have had storms of that magnitude. When it hits right on everybody's house, it's kind of a different deal.

Ted Simons: When the buildout continues in Maricopa County where there were no houses, there are now, flooding.

Steve Waters: Very much so. In a storm like this we get rainfall amounts that overtax the drainage systems put in place. And then people say, well, you know, this huge storm and retention basins are not working and storm sewers are not working. Those are designed to carry a certain load based on the money available for them. In a storm like this they are going to be overtaxed.

Ted Simons: As far as the areas hit worst, what have you seen? In terms of flooding.

Steve Waters: In terms of flooding, probably Southeast Valley, areas around Chandler and Gilbert and Mesa. There was flooding of course in the freeways. And again there are some structures that were overtaxed, weren't able to do their jobs quite like they should. So people suffered as a result.

Ted Simons: Were any of the areas that flooded of note, unusual? Are these the places that usually get flooding when we have hard rain, or was this that and then some?

Steve Waters: Well, when we get hard rain we identify always new areas that are prone to flooding. We can't plan and model every area of the Valley. So when we have a storm that hits on the north-south of South Mountain or the urban areas, we identify new areas that are prone to flooding.

Ted Simons: Basically you learn with each storm, don't you?

Steve Waters: Oh, very much so. We have project managers and planners whose job it is to design facilities that are new and taking care of new water. And when we good and the storm like this they are out in the field. They are looking at their project areas and seeing where those problems are.

Ted Simons: And in general, then, the retention basins did what they were supposed to do?

Steve Waters: Let's talk about that for a second. There are detention basins with little developments. There are neighborhood sized detention basins, regional detention basins and they are all sized to different storms. Again, depending on the amount of money people want to spend on those. Detention basins designed for two or 10-year storms, yeah, they were overtaxed and probably spilled and did all kinds of stuff. The newest detention base we have out at Levine on the North side got to 90% but did its job.

Ted Simons: Levine is hit all the time.

Steve Waters: It has been this summer, other summers, no.

Ted Simons: Storms have been coming a lot from the west, it seems and new spots breaking out all the time.

Steve Waters: We've had a couple of very early season low pressure systems coming off the Pacific that have interacted with moisture coming from the South. That's caused the events of August 19th and the one yesterday to just be way worse than they usually are, because most of the time we have the moisture that comes from the northeast. As it comes downslope from the mountains, the air falls with it. But when it goes the other way, the air lifts up as it's moving and drops that much more rain.

Ted Simons: So it looks like things are getting back to normal here. We'll see what happens with storms tonight and maybe a touch or so tomorrow. Things are getting back and we hope the folks in Mesa are getting back too - because they are really -- and that was again regarding freeway stuff and, again, just a freak of geography?

Steve Waters: There may have been a little bit of influence from the upcoming El Nino. Early in the season we had one of the earliest ever category 5 storms in the East Pacific. We've had Hurricane Norbert come up and peel moisture into the southern U.S and having that interacting with the tropic come through.

Ted Simons: Before you go, we have a couple of shots just to prove these storms do happen. We have a shot from 1905, the state capitol. This looks like it could be an old photograph from a day or two ago, as far as the state capitol just absolutely being inundated with rain.

Steve Waters: Right. The state capitol is in the historic floodplain of Cave Creek. And Cave Creek now has a nice big dam up at Joe Max road. But back then, Cave Creek flowed to the Salt River. And the state capitol was in the way. When they had a big storm on upper Cave Creek, the state capitol would get flooded and actually a flooding of the capitol in the 1950s is what caused the legislature to create flood control districts in Arizona.

Ted Simons: Isn't that interesting? We have another shot of the capitol underwater during a flood. I think it was the same flood in 1905.

Steve Waters: Right, horse-drawn buggies, but still don't cross flooded recognize even with your horse.

Ted Simons: In the 1930s we have a lot of folks in Gilbert, Arizona, doing what's coming naturally.

Steve Waters: This was a storm in the '30s. There was also a big storm in the Southeast Valley in 1954. But the Corps of Engineers used to design the big dam that we see now.

Ted Simons: For this storm, coming up at 9th and Northern there was a canal break. This is 9th street and Northern.

Steve Waters: Wow.

Ted Simons: And this produced all this rain, they still weren't as much as yesterday, were they?

Steve Waters: Nope. In some places, no. For instance, the storm of June 1972, there were recorded amounts of five inches. But not quite in as large of an area as we saw yesterday.

Ted Simons: Those are some historical photos there to put it all into perspective. When we have storms, how -- is there a temptation to go too far too protect from these kinds of things? You know what I mean? You to build 100-year or thousand-year -- but even you were saying these weren't made for those. How do you work into the future with something like this?

Steve Waters: Well, you keep doing what you're doing. As the flood control district for Maricopa County, we look at a regional approach. We've been building structures over the years, dams and channels that protect large areas of land. The developers, they can do what they can do. Every city in the county has a little different drainage standard of how they want things built. But you're right, there can be a tendency to overdesign. And in my opinion, the big Corps dams on the north side of town were overdesigned. They are huge, they hold tons and tons and tons of water.

Ted Simons: Some of them got tons and tons of water yesterday. Good to have you here.

Steve Waters: My pleasure.
 

Steve Waters:Flood Warning Branch Manager, Flood Control District of Maricopa County;

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