WEBVTT

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- [Narrator] During the spring of 2015,

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rain inundated Oklahoma and North Texas

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causing widespread flooding.

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The amount of water flowing into Corps Of Engineer lakes

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rivaled the worst floods in the history of the area.

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More water than floods in the 1920s and 40s

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when one flood, in particular, in 1943,

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wiped out whole towns in South Eastern Oklahoma.

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During it all, the flood risk management structures,

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the dams and levies, did what they were designed to do,

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minimize the amount of flooding.

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Even then, one question came up more than others,

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why no prerelease?

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Why doesn't the Corps release water from a dam

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before the rainfalls, essentially adding space

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to the flood pool?

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Doesn't the Corps keep track of rain forecasts?

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Forecasts can be wrong and even the slightest difference

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between the forecasts and where the rain actually falls

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can spell catastrophe.

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^- Say you did do prerelease

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^and the rainfall doesn't fall in the water shed,

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it falls below the dam, three to five inches.

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We've got the river at channel capacity

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thinking it's gonna fall upstream,

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it falls downstream, guess what happens?

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You just flooded a lot of people.

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- [Narrator] So, the Corps waits until the water

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is on the ground, measured in the inlet channels

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and tributaries before making decisions on water release.

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^- All of our major releases are always based

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^on water that's already fallen on the ground

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^and is in the process of coming in to our reservoirs

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and is going to impact our reservoirs and fill it up.

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Then we make our decisions on what we release

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at that point.

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- [Narrator] With that in mind, water managers run models,

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gather data from upstream gauges,

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and, of course, monitor weather patterns.

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They then follow a plan of water release

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depending on the amount of water

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actually flowing into the lake.

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Now you know why we don't normally prerelease water.

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You can get more information on water releases

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by going to our website at WWW.SWT.USACE.Army.Mil.

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There you will find a wealth of information

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by clicking on the blue water control data system button

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including real-time gauge data for reservoirs and streams.