# Opening Flood Gates? **URL:** \ **Category:** Factual Questions\ **Created:** [May 15, 2011, 1:08pm UTC](https://boards.straightdope.com/t/opening-flood-gates/581978 "2011-05-15T13:08:20Z")\ **Posts on this page:** 20\ **Page:** 1
**Author:** ![Jinx](https://avatars.discourse-cdn.com/v4/letter/j/c6cbf5/32.png) [@Jinx](https://boards.straightdope.com/u/Jinx)\ **Post date:** [May 15, 2011, 1:08pm UTC](https://boards.straightdope.com/t/opening-flood-gates/581978/1 "2011-05-15T13:08:20Z")
Am I missing something in the news story about opening flood gates on the mighty Mississippi upstream of New Orleans? How does opening these gates help save New Orleans? The water STILL has to go somewhere, and New Orelans is STILL at the lowest point!?! Am I missing something here? Wouldn’t draining-off the water from dams upstream at a slower pace make more sense??? ---
**Author:** ![johnpost](https://avatars.discourse-cdn.com/v4/letter/j/f17d59/32.png) [@johnpost](https://boards.straightdope.com/u/johnpost)\ **Post date:** [May 15, 2011, 1:35pm UTC](https://boards.straightdope.com/t/opening-flood-gates/581978/2 "2011-05-15T13:35:15Z")
there are locks and dams/spillways on the northern Mississippi River due to elevation to permit navigation of that part of the river. the lower river is open to navigation. these flood gates divert the river through its normal course (sideways) into areas intended to be flooded in high water situations. ---
**Author:** ![Shagnasty](https://avatars.discourse-cdn.com/v4/letter/s/9dc877/32.png) [@Shagnasty](https://boards.straightdope.com/u/Shagnasty)\ **Post date:** [May 15, 2011, 1:51pm UTC](https://boards.straightdope.com/t/opening-flood-gates/581978/3 "2011-05-15T13:51:33Z")
You are missing the fact that the area where they are opening the gates is quite flat and over 100 miles from New Orleans. Allowing a giant area to flood to shallow depth lightens the load on the main river channel immediately but it also makes so that much of the water will never reach New Orleans. Some of it will soak into the ground or evaporate over time. ---
**Author:** ![Exapno\_Mapcase](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/exapno_mapcase/32/1051_2.png) [@Exapno\_Mapcase](https://boards.straightdope.com/u/Exapno_Mapcase)\ **Post date:** [May 15, 2011, 1:54pm UTC](https://boards.straightdope.com/t/opening-flood-gates/581978/4 "2011-05-15T13:54:52Z")
There aren’t any dams on the Mississippi either. Flood gates are not dams in the normal sense. ---
**Author:** ![zagloba](https://avatars.discourse-cdn.com/v4/letter/z/977dab/32.png) [@zagloba](https://boards.straightdope.com/u/zagloba)\ **Post date:** [May 15, 2011, 2:17pm UTC](https://boards.straightdope.com/t/opening-flood-gates/581978/5 "2011-05-15T14:17:38Z")
> [@Exapno\_Mapcase](#): > > There aren’t any dams on the Mississippi either. Flood gates are not dams in the normal sense. Well, there are dams on the Mississippi, but none south of St. Louis, I believe. ---
**Author:** ![excavating\_for\_a\_mind](https://avatars.discourse-cdn.com/v4/letter/e/e8c25b/32.png) [@excavating\_for\_a\_mind](https://boards.straightdope.com/u/excavating_for_a_mind)\ **Post date:** [May 15, 2011, 3:21pm UTC](https://boards.straightdope.com/t/opening-flood-gates/581978/6 "2011-05-15T15:21:44Z")
> [@Jinx](#): > > Am I missing something in the news story about opening flood gates on the mighty Mississippi upstream of New Orleans? How does opening these gates help save New Orleans? The water STILL has to go somewhere, and New Orelans is STILL at the lowest point!?! Am I missing something here? Wouldn’t draining-off the water from dams upstream at a slower pace make more sense??? What you are missing is that the Atchafalaya basin (swamp, whatever) does not drain to the Mississippi River, but to the Gulf of Mexico through the Atchafalaya River. In fact, the Mississippi would naturally have already changed its course to flow into the Atchafalaya River had the Army Corps of Engineers not built the series of levees and flood gates early in the last century. This was done mainly to keep the Port of New Orleans a commercial port, which it would not be if the Mississippi drained into the Gulf 100 miles west of its current location. excavating (for a mind) ---
**Author:** ![ZenBeam](https://avatars.discourse-cdn.com/v4/letter/z/3ab097/32.png) [@ZenBeam](https://boards.straightdope.com/u/ZenBeam)\ **Post date:** [May 15, 2011, 3:27pm UTC](https://boards.straightdope.com/t/opening-flood-gates/581978/7 "2011-05-15T15:27:49Z")
Opening the [Morganza spillway](http://en.wikipedia.org/wiki/Morganza_Spillway) allows Mississippi water to flow into the [Atchafalaya river](http://en.wikipedia.org/wiki/Atchafalaya_River), which means it won’t flow past New Orleans. That second link has a simple map. The Morganza spillway is where the Atchafalaya meets the Mississippi. ---
**Author:** ![GaryM](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/garym/32/241_2.png) [@GaryM](https://boards.straightdope.com/u/GaryM)\ **Post date:** [May 15, 2011, 8:02pm UTC](https://boards.straightdope.com/t/opening-flood-gates/581978/8 "2011-05-15T20:02:51Z")
> [@zagloba](#): > > Well, there are dams on the Mississippi, but none south of St. Louis, I believe. Correct. The furthest South dam, and accompanying navigation locks, is the [Chain of Rocks](http://en.wikipedia.org/wiki/Chain_of_Rocks_Lock). This is located just South of where Interstate 270 crosses into Illinois. All the rest of the river to the South is free flowing. ---
**Author:** ![septimus](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/septimus/32/410_2.png) [@septimus](https://boards.straightdope.com/u/septimus)\ **Post date:** [May 15, 2011, 10:26pm UTC](https://boards.straightdope.com/t/opening-flood-gates/581978/9 "2011-05-15T22:26:59Z")
> [@ZenBeam](#): > > Opening the [Morganza spillway](http://en.wikipedia.org/wiki/Morganza_Spillway) allows Mississippi water to flow into the [Atchafalaya river](http://en.wikipedia.org/wiki/Atchafalaya_River), which means it won’t flow past New Orleans. Thanks for the link. I learned a new word. > [@](#): > > The Atchafalaya River is a 170-mile distributary of the Mississippi River and Red River … ---
**Author:** ![FoieGrasIsEvil](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/foiegrasisevil/32/16638_2.png) [@FoieGrasIsEvil](https://boards.straightdope.com/u/FoieGrasIsEvil)\ **Post date:** [May 15, 2011, 11:29pm UTC](https://boards.straightdope.com/t/opening-flood-gates/581978/10 "2011-05-15T23:29:10Z")
I hope nobody is blaming the Corps of Engineers for any of this shit. Rivers flood, rains fall more some years than others, and there’s only so much control one can exert over a huge mass of moving water. ---
**Author:** ![Shagnasty](https://avatars.discourse-cdn.com/v4/letter/s/9dc877/32.png) [@Shagnasty](https://boards.straightdope.com/u/Shagnasty)\ **Post date:** [May 16, 2011, 12:40am UTC](https://boards.straightdope.com/t/opening-flood-gates/581978/11 "2011-05-16T00:40:11Z")
> [@FoieGrasIsEvil](#): > > I hope nobody is blaming the Corps of Engineers for any of this shit. Rivers flood, rains fall more some years than others, and there’s only so much control one can exert over a huge mass of moving water. I haven’t heard anyone saying that. However, if anyone does, they have never witnessed the size and power of the lower Mississippi. It is one of the biggest rivers in the world and handles some of the largest ships in the world including cruise ships and aircraft carriers. It is a miracle that they have been able to keep it in its current channel for this long. If it managed to change channels, God help us because we are just fleas on a dog in the fight. ---
**Author:** ![FoieGrasIsEvil](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/foiegrasisevil/32/16638_2.png) [@FoieGrasIsEvil](https://boards.straightdope.com/u/FoieGrasIsEvil)\ **Post date:** [May 16, 2011, 12:57am UTC](https://boards.straightdope.com/t/opening-flood-gates/581978/12 "2011-05-16T00:57:14Z")
> [@Shagnasty](#): > > I haven’t heard anyone saying that. However, if anyone does, they have never witnessed the size and power of the lower Mississippi. It is one of the biggest rivers in the world and handles some of the largest ships in the world including cruise ships and aircraft carriers. It is a miracle that they have been able to keep it in its current channel for this long. If it managed to change channels, God help us because we are just fleas on a dog in the fight. Its akin to the blame many people assigned to the Corps over Katrina. The levees there were built in accordance with the projection of facing a certain level of hurricane and also the funding available to construct it. I know some folks are upset with the Corps blowing up levees further upriver to help spare the more populated areas downriver…but what else are you going to do? Risk major population centers in favor of 3,000 farms? It was a bad choice, but a necessary one. As you say…essentially, the river always wins. ---
**Author:** ![Shawn1767](https://avatars.discourse-cdn.com/v4/letter/s/ee7513/32.png) [@Shawn1767](https://boards.straightdope.com/u/Shawn1767)\ **Post date:** [May 16, 2011, 1:36am UTC](https://boards.straightdope.com/t/opening-flood-gates/581978/13 "2011-05-16T01:36:57Z")
This may help your understanding: [Portal Berita Milenial Paling Update](http://images.bimedia.net/images/inundationmap.jpg) ---
**Author:** ![ElvisL1ves](https://avatars.discourse-cdn.com/v4/letter/e/5daacb/32.png) [@ElvisL1ves](https://boards.straightdope.com/u/ElvisL1ves)\ **Post date:** [May 16, 2011, 1:37am UTC](https://boards.straightdope.com/t/opening-flood-gates/581978/14 "2011-05-16T01:37:22Z")
John McPhee discussed the subject very well [here](http://www.newyorker.com/archive/1987/02/23/1987_02_23_039_TNY_CARDS_000347146?currentPage=all). Pre-Katrina but still applicable and still very readable. ---
**Author:** ![Oslo\_Ostragoth](https://avatars.discourse-cdn.com/v4/letter/o/a9a28c/32.png) [@Oslo\_Ostragoth](https://boards.straightdope.com/u/Oslo_Ostragoth)\ **Post date:** [May 16, 2011, 1:46am UTC](https://boards.straightdope.com/t/opening-flood-gates/581978/15 "2011-05-16T01:46:54Z")
> [@ElvisL1ves](#): > > John McPhee discussed the subject very well [here](http://www.newyorker.com/archive/1987/02/23/1987_02_23_039_TNY_CARDS_000347146?currentPage=all). Pre-Katrina but still applicable and still very readable. Very nice. I’m going to set aside some time to read that. ---
**Author:** ![chacoguy](https://avatars.discourse-cdn.com/v4/letter/c/50afbb/32.png) [@chacoguy](https://boards.straightdope.com/u/chacoguy)\ **Post date:** [May 16, 2011, 1:59am UTC](https://boards.straightdope.com/t/opening-flood-gates/581978/16 "2011-05-16T01:59:02Z")
I’ve posted this elsewhere, but the Morganza Spillway has a capacity of 600,000 cubic feet a second. The Colorado River is near here and expected to crest higher than it has in decades. 600,000 cfs is almost _200 times_ what we are expecting. ---
**Author:** ![Musicat](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/musicat/32/20189_2.png) [@Musicat](https://boards.straightdope.com/u/Musicat)\ **Post date:** [May 16, 2011, 2:08am UTC](https://boards.straightdope.com/t/opening-flood-gates/581978/17 "2011-05-16T02:08:32Z")
> [@FoieGrasIsEvil](#): > > I hope nobody is blaming the Corps of Engineers for any of this shit. On the contrary. If the Corps of Engineers hadn’t restricted the river to a narrow channel, preventing it from finding a natural course, and preventing it from soaking into large tracts of land the way it used to, this year’s problems would be a lot less. The Corps is totally responsible for the height of the river and the resulting damage thereof. That’s not to say that there wouldn’t be damage without the controls, but it would be different. You can’t fool Mother Nature. ---
**Author:** ![ElvisL1ves](https://avatars.discourse-cdn.com/v4/letter/e/5daacb/32.png) [@ElvisL1ves](https://boards.straightdope.com/u/ElvisL1ves)\ **Post date:** [May 16, 2011, 2:15am UTC](https://boards.straightdope.com/t/opening-flood-gates/581978/18 "2011-05-16T02:15:32Z")
The Corps is only following the law. Congress requires it to control the Mississippi’s flow the way it is. ---
**Author:** ![YogSothoth](https://avatars.discourse-cdn.com/v4/letter/y/8edcca/32.png) [@YogSothoth](https://boards.straightdope.com/u/YogSothoth)\ **Post date:** [May 16, 2011, 2:16am UTC](https://boards.straightdope.com/t/opening-flood-gates/581978/19 "2011-05-16T02:16:30Z")
> [@chacoguy](#): > > I’ve posted this elsewhere, but the Morganza Spillway has a capacity of 600,000 cubic feet a second. The Colorado River is near here and expected to crest higher than it has in decades. 600,000 cfs is almost _200 times_ what we are expecting. How do you even prepare for something like that? :eek:😕 ---
**Author:** ![NinetyWt](https://avatars.discourse-cdn.com/v4/letter/n/cc9497/32.png) [@NinetyWt](https://boards.straightdope.com/u/NinetyWt)\ **Post date:** [May 16, 2011, 2:28am UTC](https://boards.straightdope.com/t/opening-flood-gates/581978/20 "2011-05-16T02:28:38Z")
> [@YogSosoth](#): > > How do you even prepare for something like that? :eek:😕 You use a big cross-section. 😃 The Mississippi, as it passes New Orleans, can handle 1.2 million cfs. > [@Musicat](#): > > The Corps is totally responsible for the height of the river and the resulting damage thereof. No, the public demanded that levees be built. The Corps has merely done what Congress and the people have asked them to do: > [@](#): > > Extreme floods along the Mississippi in 1927 floods led the U.S. Congress to pass to the Flood Control Act of 1928, authorizing construction of levees, floodways, and other landscape modifications to control the flow of the Mississippi River. [Next page](https://boards.straightdope.com/t/opening-flood-gates/581978.md?page=2)