being in the mountainous areas, they didn't need to worry about floods as big as the ones
that we were looking at over in the plains. They said, "Well, storms won't move as far
in the mountains. You can't transpose a major storm from one location to the other in the
mountain areas like you can out in the open area where you don't have big mountains.
There was a lot of controversy between the Weather Service and the Bureau of
Reclamation about transposing storms. If you didn't transpose a storm very far and there
weren't any other big storms in your area, you could say that the potential was small there.
So there was a lot of controversy. That was a big reason why the Corps was having a lot
larger probable maximum floods than the Bureau of Reclamation.
The SCS, they used the National Weather Service to get their probable maximum precip
[precipitation], same as the Corps did, but they didn't put freeboard on their dams. They
would design the dam to take care of the highest level attained by that probable maximum
flood without any freeboard. The Corps always added freeboard on their dams.
I guess the SCS could argue that since their dams were usually small dams, they didn't
need to worry about wave overtopping, run-up and waves overtopping, as much as the
Corps did on it's big dams. So they had less conservative design than the Corps. Then
you get into the states and the kind of requirements they put on--a lot of states didn't have
any requirements. They would let you build almost any kind of dam you wanted to, and
the states wouldn't care.
Since the big dam safety study several years ago that the Corps did and many dam failures,
they've gotten a lot of the states to put in requirements. A lot of the states have adopted
the standards we used to investigate whether a dam was safe or not. They use the same
kinds of standards that we put together to evaluate the non-Federal dams. Those standards
were really not supposed to be design standards. They were supposed to be standards to
look at existing projects under the concept that it's awfully hard to change an existing
project. It's better to spend more money in the original design.
So we set up some criteria that weren't quite as strong as what we would have wanted
them to use if they were building a new project. But just to find out whether they were
reasonably safe or not. But states picked that up and said, "Well, that's design criteria.
Our view of it was safety evaluation criteria, not design criteria. They say they're one and
the same. But, anyway, that was interesting. At least it increased the design level most
states were using.
Then they have a big problem if there's no development downstream from the dam, a lot
of these states won't have a major requirement on how you build the dam. Maybe they' 11
use a
flood or even less in designing the dam because there's nobody living
Previous Page
