158:, a natural log jam that was obstructing the Atchafalaya River. The project was finished in 1840. After that, the Lower Old River would flow eastward to the Mississippi when the Red River was high and the Mississippi was low, and westward to the Atchafalaya when the Mississippi was high and the Red River was low. Over time, the number of days when the river flowed east to the Mississippi decreased and the number of days when the river flowed west increased, until eventually the Lower Old River flowed west over half the time. By 1880, it rarely flowed eastward and was rapidly capturing more and more of the flow of the Mississippi. With this increased water flow, the channel of the Atchafalaya River was worn deeper and wider throughout the 1800s and early 1900s.
232:
290:, between the Mississippi and the Atchafalaya Basin nearby downstream, is normally closed. It can be opened in an emergency to relieve water levels and water-pressure stress on various levees and other flood-control structures, including the Old River Control Structure. The floodway can reduce stress by diverting additional water from the Mississippi into the Atchafalaya. The Morganza Floodway was never used before the construction of Old River Control Structure, and as of 2016 has been opened only twice for flood control since completion of the Old River Control Structure.
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Structure is only used when the
Mississippi exceeds its banks. The ORCAS is used during floods to assist the ORCS and prevent it from being damaged due to high flow rates. ORCAS was added to reduce pressure on the original floodgates after extensive damage caused by the flood of 1973. The northernmost and newest structure is the
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Water from the
Mississippi is normally diverted into the Atchafalaya Basin only at Old River, where floodgates are routinely used to redirect the Mississippi's flow into the Atchafalaya River, such that the volume of the two rivers is split 70%/30%, respectively, as measured at the latitude of Red
243:
The Old River
Control Structure (ORCS) and Overbank Control Structure became operational in 1964 and expanded in 1986 with the addition of the Old River Control Auxiliary Structure (ORCAS). The primary one that regulates routine flow in the waterway is the Low Sill Control Structure. The Overbank
169:
Between 1850 and 1950, the percentage of latitude flow entering the
Atchafalaya River had increased from less than 10 percent to about 30 percent. By 1953, the U.S. Army Corps of Engineers concluded that the Mississippi River could change its course to the Atchafalaya River by 1990 if it were not
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A navigation channel and lock are also part of the facility design, but they are situated well south of the other structures on the Lower Old River at the Old River Lock. This makes the Lower Old River navigable, allowing ship and barge traffic between the
Mississippi River and the Atchafalaya
134:
along the
Mississippi River, such a vessel would need several hours to travel the 20 miles (32 km) of Turnbull's Bend, after which it would have progressed only about 1 mile (1.6 km) from the entrance to the bend. To reduce travel time, Captain
143:, Louisiana, dug a canal in 1831 through the neck of Turnbull's Bend; this canal became known as Shreve's Cut. At the next high water, the Mississippi roared through this channel. The upper portion of Turnbull's Bend was referred to as
177:
The Corps completed construction on the Old River
Control Structure in 1963 to prevent the main channel flow of the Mississippi River from altering its current course to the Gulf of Mexico through the natural geologic process of
182:. Historically, this natural process of course change has occurred about every 1,000 years, and is overdue. Some researchers believe the likelihood of this event increases each year, despite manmade artificial control efforts.
161:
The U.S. Army Corps of
Engineers measured the amount of water flowing through the Mississippi River and compared it to the amount entering the Atchafalaya Basin by monitoring "latitude flow" at the latitude of the
436:
90:
The Old River
Control Structure is a complex containing the original low-sill and overbank structures, as well as the auxiliary structure that was constructed after the low-sill structure was damaged during the
166:, located five miles (8.0 km) downstream of Old River. In this case, latitude flow is a combination of the flows of the Mississippi and Atchafalaya rivers as they cross an imaginary line at that latitude.
763:
248:, completed in 1990. It provides an additional measure of control at the site. These four structures are located approximately where the Upper Old River used to be before Shreve's Cut.
272:
River
Landing. This flow split was not based on science, but rather was based on the approximate flow allocation between the two rivers that existed at the time of construction.
404:
773:
263:, starting at the power plant, then the Overbank Structure, then the Low Sill ORCS, followed by ORCAS, the island created between the rivers, and finally the Old River Lock.
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and Mississippi River were entirely separate and flowed more or less parallel to one another. Beginning in the 15th century, the Mississippi River created a small, westward,
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123:. This loop eventually intersected the Red River, making the downstream part of the Red River a distributary of the Mississippi; this distributary came to be called the
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Water diverted at Old River flows into the Atchafalaya Basin, first entering the Red River, then continuing down the Atchafalaya River to the Gulf of Mexico, bypassing
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almost caused the control structure to fail. Maintenance of the integrity of the Old River Control Structure, the nearby
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At first, the Lower Old River would flow eastward, to the Mississippi, until 1839, when locals began removing the
79:, thereby preventing the Mississippi River from changing course. Completed in 1963, the complex was built by the
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in a side channel of the Mississippi known as "Old River", between the Mississippi's current channel and the
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95:. The complex also contains a navigation lock and the Sidney A. Murray Jr. Hydroelectric Station.
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217:, and other levees in the area is essential to prevent such a diversion. Jeff Masters of
668:"Morganza Floodway opens to divert Mississippi River away from Baton Rouge, New Orleans"
371:
171:
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Formation of the Atchafalaya River and construction of the Old River Control Structure.
24:
752:
55:
Old River low-sill control structure discharging water into the Atchafalaya, May 2011
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noted that failure of that complex "would be a serious blow to the U.S. economy."
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in southern Louisiana, greatly reducing water flow to its present channel through
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405:"Louisiana Old River Control Structure and Mississippi river flood protection"
155:
734:
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411:. Loyola University's Center for Environmental Communication. Archived from
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72:
64:
593:"Mississippi River sets all-time flood records; 2nd major spillway opens"
641:"Daily State and Discharge Data - Water Control - New Orleans District"
510:
The Atchafalaya River Basin: History and Ecology of an American Wetland
437:"Will the Mississippi River change its course in 2011 to the red line?"
116:
617:. United States Army Corps of Engineers. May 7, 2011. Archived from
686:"Morganza Floodway will not be opened, Corps of Engineers decides"
460:"The Mississippi Levee System and the Old River Control Structure"
230:
102:
50:
18:
75:. It regulates the flow of water from the Mississippi into the
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through the Atchafalaya River is much shorter and steeper.
47:, is in the background, across the Mississippi on the left.
209:, with adverse economic effects on both port cities. The
23:
The Old River Control Structure complex. View is to the
764:
Buildings and structures in Concordia Parish, Louisiana
578:
On Risk and Disaster: Lessons from Hurricane Katrina
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while the larger, lower portion became known as the
235:A diagram that depicts river flows associated with
185:If the Mississippi diverts its main channel to the
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119:, later called Turnbull's Bend, near present-day
615:"Mississippi River at Red River Landing (01120)"
431:
429:
580:. University of Pennsylvania Press. p. 45.
537:"$ 500 Million (and Rising) to Contain a River"
488:"Old River Control Structure, Point Breeze, LA"
170:controlled, since this alternative path to the
643:. U.S. Army Corps of Engineers. Archived from
8:
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774:United States Army Corps of Engineers dams
246:Sidney A. Murray Jr. Hydroelectric Station
531:
529:
259:All five structures in the complex carry
87:, a former channel of the Mississippi.
43:is in the foreground, on the right, and
310:
555:"Mississippi Rising: Apocalypse Now?"
7:
320:"The Control of Nature: Atchafalaya"
458:Kemp, Katherine (January 6, 2000).
139:, a river engineer and namesake of
512:. Texas A&M University Press.
318:McPhee, John (February 23, 1987).
16:Floodgate system in Louisiana, USA
14:
409:America's Wetland Resource Center
39:to the right of the Mississippi.
779:1963 establishments in Louisiana
543:. Associated Press. May 3, 1987.
93:Mississippi River Flood of 1973
35:across channels leading to the
557:. Daily Impact. April 28, 2011
1:
704:"Old River Control Structure"
591:Masters, Jeff (May 9, 2011).
576:Daniels, Ronald Joel (2006).
341:. Farrar, Straus and Giroux.
111:Before the 15th century, the
45:Wilkinson County, Mississippi
666:Rioux, Paul (May 14, 2011).
383:. Includes map and pictures.
368:The Mighty Mississippi River
81:U.S. Army Corps of Engineers
61:Old River Control Structure
41:Concordia Parish, Louisiana
27:, looking downriver on the
795:
769:Dikes in the United States
67:system in a branch of the
508:Piazza, Bryan P. (2014).
211:Mississippi flood of 1973
193:, it would develop a new
362:Angert, Joe and Isaac.
300:Lower Mississippi River
254:Red River of the South
240:
108:
56:
48:
621:on September 27, 2011
595:. Weather Underground
339:The Control of Nature
337:McPhee, John (1989).
234:
106:
54:
22:
688:. 27 September 2023.
474:"Low Sill Structure"
261:Louisiana Highway 15
237:Project Design Flood
735:31.0768°N 91.5979°W
731: /
364:"Old River Control"
220:Weather Underground
541:The New York Times
241:
109:
57:
49:
759:Atchafalaya River
740:31.0768; -91.5979
519:978-1-62349-039-3
492:www.johnweeks.com
348:978-0-374-12890-6
288:Morganza Floodway
215:Morganza Spillway
191:Atchafalaya River
187:Atchafalaya Basin
164:Red River Landing
130:In the heyday of
125:Atchafalaya River
121:Angola, Louisiana
85:Atchafalaya Basin
77:Atchafalaya River
69:Mississippi River
37:Atchafalaya River
31:, with the three
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370:. Archived from
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145:Upper Old River,
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335:Republished in
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283:(see diagram).
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149:Lower Old River
137:Henry M. Shreve
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324:The New Yorker
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172:Gulf of Mexico
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25:east-southeast
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649:. Retrieved
645:the original
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623:. Retrieved
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599:November 11,
597:. Retrieved
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738: /
281:New Orleans
277:Baton Rouge
207:New Orleans
203:Baton Rouge
199:Morgan City
71:in central
29:Mississippi
753:Categories
726:91°35′52″W
723:31°04′36″N
709:2014-09-20
419:2007-04-01
378:2011-05-12
306:References
227:Components
156:Great Raft
141:Shreveport
132:steamboats
117:oxbow loop
267:Operation
197:south of
113:Red River
99:Old River
73:Louisiana
65:floodgate
672:NOLA.com
294:See also
189:and the
180:avulsion
651:May 10,
625:May 10,
561:May 10,
329:May 12,
516:
443:May 8,
345:
252:River/
195:delta
63:is a
653:2011
627:2011
601:2017
563:2011
514:ISBN
445:2011
343:ISBN
331:2011
286:The
279:and
205:and
59:The
33:dams
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Text is available under the Creative Commons Attribution-ShareAlike License. Additional terms may apply.
