Drainage has long been a major concern in New Orleans due to much of the city being below sea level. The city built levees to prevent flooding from the Mississippi River and Lake Pontchartrain, but this also prevented drainage of rainfall. Hurricane Katrina in 2005 caused catastrophic flooding when levees and floodwalls failed in multiple locations, submerging 80% of the city under water. Since then, efforts have focused on repairing and improving the drainage system and flood protections to prevent a similar disaster from occurring again.

1. Drainage in New Orleans
From Wikipedia, the free encyclopedia
Elevation map of New Orleans. Blue/purple indicates elevations below the average level of Lake
Pontchartrain (1983-2001) and orange/brown indicates elevations above.
Vertical cross-section of New Orleans, showing maximum levee height of 23Â feet
Drainage in New Orleans, Louisiana has been a major concern since the founding of the city in the

2. early 18th century, remaining an important factor in the history of New Orleans today. The central
portion of metropolitan New Orleans (New Orleans/Metairie/Kenner) is fairly unique in that it is
almost completely surrounded by water: Lake Pontchartrain to the north, Lake Borgne to the east,
wetlands to the east and west, and the Mississippi River to the south. Much of the land area between
these bodies of water is at or below sea level, and no longer has a natural outlet for flowing surface
water. As such, virtually all rainfall occurring within this area must be removed through either
evapotranspiration or pumping. Thus, flood threats to metropolitan New Orleans include the
Mississippi River, Lake Pontchartrain, and natural rainfall. Artificial levees have been built to keep
out rising river and lake waters but have had the negative effect of keeping rainfall in.
Contents
1 History
2 Hurricane Katrina
2.1 After Katrina
3 See also
4 References
5 External links
History
New Orleans was originally built on natural levees along the Mississippi River that were a result of
soil deposits left from the river's annual floods. The site chosen for New Orleans had many
advantages. Because it sits where distance between the river and Lake Pontchartrain is shortest,
Louisiana Indians had long used the area as a depot and market for goods carried between the two
waterways. The narrow strip of land also aided rapid troop movements, and the river's crescent
shape slowed ships approaching from downriver and exposed them to gunfire,[1] however flooding
was always a hazard.
The first artificial levees and canals were built in early colonial times. They were erected to protect
New Orleans against routine flooding from the Mississippi River. The "back of town" away from the
river originally drained down into the swamps running toward Lake Pontchartrain. Flooding from
the lake side was rare and less severe as most of the old town had been built on high ground along
the riverfront.
As the city grew, demand for more land encouraged expansion into lower areas more prone to
periodic flooding. For most of the 19th century most residential buildings were raised up at least a
foot above street level (often several feet), since periodic flooding of the streets was a certainty at
the time.
In the 1830s state engineer George T. Dunbar proposed an ambitious system of underground
drainage canals beneath the streets. The goal was to drain water by gravity into the low lying
swamps, supplementing this with canals and mechanical pumps. The first of the city's steam engine
powered drainage pumps, adapted from a ship's paddle wheel and used to push water along the
Orleans Canal out to Bayou St. John, was constructed in this decade. However, only a few of
Dunbar's plans were actually implemented as the panic of 1837 largely ended major systematic

3. improvements for a generation.
In 1859 surveyor Louis H. Pilié improved the drainage canals, bricking in some portions. Four
large steam "draining machines" were built to push water through the canals into the lake.
In 1871, some 36 miles (58Â km) of canals were built in the city for both improved drainage and
small vessel shipping within town. However, despite earlier efforts, at the end of the 19th century it
was still common for water to cover streets from curb to curb after rainstorms, sometimes for days.
In 1893, the city government formed the Drainage Advisory Board to come up with better solutions
to the city's drainage problems. Extensive topographical maps were made and some of the nation's
top engineers were consulted. In 1899, a bond was floated, and a 2 mill per dollar property tax
approved, which funded and founded the Sewerage & Water Board of New Orleans. The Sewerage &
Water Board had the responsibility of draining the city along with constructing a modern sewage
and tap water system for the city, which, at the time, still relied heavily on cisterns and outhouses.
(A different entity, the Orleans Levee Board, is in charge of supervision of the city's levee and
floodwall system.)
The Sewerage & Water Board found A. Baldwin Wood, a young engineer who not only supervised the
plans for improved drainage and pumping, but also invented a number of improvements in pumps
and plumbing in the process. These improvements were not only used in New Orleans, but adopted
all over the world.
The central power plant for the pumping stations of the New Orleans drainage system, 1904
As the 20th century progressed, much of the land that had previously been swampland or considered
fit for no other use than cow pasture (due to periodic flooding), was drained. The city then expanded
back from the natural higher ground close to the river and the natural bayou formed ridges.
On 15 April 1927 in what became known as the Great Mississippi Flood of 1927, the city was
deluged by a downpour of some 15 inches (380Â mm) of rain within 19 hours. At the time, almost all
of the city's pumps relied completely on the municipal electricity system, which went out early in the
storm, thus knocking the pumps off line, which led to extensive flooding in the city. After this, back
up diesel generators with sufficient fuel to run the pumps for at least a day if electricity failed were
added to the pumping stations. The "Good Friday Flood", as it was known locally, happened when
the Mississippi River levels were dangerously high along the levees at the city, but was not directly
connected to the more wide-ranging flood.

4. 1927 also saw the start of a project to build a more extensive system of levees on the shoreline of
Lake Pontchartrain. After 1945, all land up to the lake had been developed.
The city's system was effective when the 1947 Fort Lauderdale Hurricane directly hit the city.
Wood's drainage pumps kept the city proper mostly dry, while the neighboring suburbs on the East
Bank of Jefferson Parish (which at the time did not have a comparable system operational), flooded
under up to 6 feet (1.8Â m) of water.
Most of the city weathered Hurricane Betsy in 1965 without severe flooding, with the major
exception of the Lower Ninth Ward neighborhood. The Lower Ninth Ward is separated from the rest
of the city by the Industrial Canal and Gulf Intracoastal Waterway. It was flooded not by rainfall, but
by a breach in the Industrial Canal levee, resulting in catastrophic flooding and loss of life in the
neighborhood.
By the 1980s, the city boasted a system of 20 pumping stations with 89 pumps, with a combined
capacity of 15,642,000 US gallons (59,210,000Â L) per minute, equal to the flow of the Ohio River.
In May 1995, torrential rains (up to 20 inches (510Â mm) in 12 hours in some places) overwhelmed
pumping capacity, flooding substantial portions of the city. Slab houses in some low areas were
flooded, and great numbers of automobiles on the city's flooded streets were declared insurance
write-offs. This prompted projects increasing drainage capacity in the worst hit areas.
By early 2005, the city had 148 drainage pumps.
Hurricane Katrina
Main article: Hurricane Katrina
The greatest catastrophe in the city's drainage history occurred at the end of August 2005 when it
was hit by Hurricane Katrina, after which eighty percent of the city flooded. Katrina brought tropical
storm conditions to the city starting the night of 28 August, with hurricane conditions beginning the
following day and lasting through the afternoon.
The hurricane itself did not flood the city. Rather, a series of failures in mis-designed levees and
floodwalls allowed water from the Gulf of Mexico and Lake Pontchartrain to flow into the city.
The Industrial Canal was overwhelmed when storm surge, funneled in by the Mississippi River Gulf
Outlet, overflowed and breached levees and floodwalls in several locations, flooding not only the
Lower Ninth Ward, but also Eastern New Orleans and portions of the Upper Ninth Ward west of the
Canal.
Meanwhile, waters from storm-swollen Lake Pontchartrain poured into the city, first from a breach
in the 17th Street Canal, and then from a pair of breaches in both sides of the London Avenue Canal.
These canals were among those used to channel water pumped from city streets into the lake. The
storm caused the flow to reverse, and as water levels rose the entire drainage system failed.
Examinations afterwards showed that water levels in these locations never topped the floodwalls,
but instead the levees failed with a water level supposedly within their safe tolerance.
In much of town west of the Industrial Canal, residents who did not evacuate before the storm
reported that after the storm they were relieved to see their streets dry and the precipitation from
the storm successfully pumped out. However, disaster was already spreading from the series of

5. levee breaches. In areas of town far from the breaches, flood water came not in through the streets,
but up from the storm drains beneath the street, in some places changing streets from dry to under
3 feet (0.91Â m) of water within half an hour.
Flood lines show levels of high water on this Mid City New Orleans house
By the evening of August 30, some 80% of the city was under water. (This figure includes areas of
widely differing flood levels, ranging from areas where streets were covered with water which never
rose into homes to areas where homes were entirely submerged over the rooftops.) Most of the city's
pumping stations were submerged. The few above the water line had no power and the emergency
diesel fuel had run out. These few were often tiny islands in the flood, inaccessible even if intact
enough to hypothetically be turned back on.
For most of the city to the west of the Industrial Canal, the flood levels were much the same as those
reached in mid-19th century storms when, like Katrina, major hurricanes created a "lake flood" by
pushing Lake Pontchartrain up into the South Shore. At the time of these earlier storms the lower
lying areas of the city had little development, so effects on life and property were much less severe.
West of the Industrial Canal, the parts of the city unflooded or minimally flooded largely
corresponded with areas of the city developed on naturally higher ground before 1900.
On August 31, flood levels started to subside. The water level in the city had reached that of Lake
Pontchartrain, and as the lake started to drain back into the Gulf, some water in the city started to
flow into the lake via the same levee breeches they had entered through. In 19th century lake floods,
the water soon flowed back into the lake as there were no levees on that side. In 2005, while the
levees proved inadequate to keep the lake out of the city, even in breached form they were sufficient
to keep much of the flooding from flowing back out. As breaches were gradually filled, some city
pumps were reactivated, supplemented by additional pumps brought in by the United States Army
Corps of Engineers. Some of the city's pumps which survived could not be reactivated because of the
failures of the canals that they pumped flood waters into. The combined task of closing breaches and
pumping the flood waters out took weeks and was compounded by a setback in late September due
to further flooding from Hurricane Rita.
After Katrina
Main article: 2005 levee failures in Greater New Orleans

6. See also: Civil engineering and infrastructure repair in New Orleans after Hurricane Katrina
By the start of October 2005, only a few small areas of flood waters remained within the city, but the
disastrous flooding in the aftermath of Katrina left the majority of the city's houses and businesses
so damaged as to be unusable until major renovations or repairs could be made. An article in the
New Orleans Times-Picayune on 30 November 2005 reported that studies showed the 17th Street
Canal levee was "destined to fail" as a result of fundamental design mistakes by the United States
Army Corps of Engineers.[2]
Additional investigations have found more problems with the design and construction of the London
Avenue Canal, Industrial Canal, MRGO, and other levees and flood walls.
While the majority of the city's drainage pumps were able to be reactivated after the storm, some of
the usually reliable pumps failed in 2006 due to corrosion. This was caused by wiring being
submerged in the brackish water from Katrina.
As a stop-gap measure, the Corps of Engineers installed flood gates at the mouths of the drainage
canals at Lake Pontchartrain, to be closed if the lake water level rises. While this prevents lake
waters from flowing into the vulnerable canals, it also severely limits the ability of the city to pump
out rain water while the gates are closed.
In March 2006, it was revealed that temporary pumps installed by the USACE were defective.[3][4]
Until all problems are rectified, concerns remain that parts of the city could experience significant
flooding in a storm much smaller than Katrina. The system did survive during Hurricane Gustav in
2008. The storm weakened and brought less wind and rain than forecast. "The Lakefront pumps
operated smoothly".[5]
Metarie Pumping Station, also known as Pumping Station 6, building, constructed in 1899, near
Metarie Road and the head of the 17th Street Canal. Now housing 15 Wood Screw Pumps, it can
move over 6Â billion US gallons (23,000,000Â m3) of water a day.
See also
1947 Fort Lauderdale Hurricane
Bonnet Carré Crevasse
Bonnet Carré Spillway
Effect of Hurricane Katrina on New Orleans

7. Floods in the United States: 1901-2000
Floods in the United States: 2001-present
Grand Isle Hurricane of 1909
Great Mississippi Flood of 1927
Hurricane Betsy
Hurricane Katrina
Hurricane Rita
Levee failures in Greater New Orleans, 2005
May 8th 1995 Louisiana Flood
New Orleans Hurricane of 1915
Orleans Levee Board
Sauvé's Crevasse
Southeast Louisiana Urban Flood Control Project
References
Notes
^ "The Cabildo - Colonial Louisiana". Louisiana State Museum. Retrieved 11 August 2010.
^ "?".
^ "?". Retrieved 11 August 2010.
^ "?". Retrieved 11 August 2010.
^ "?". Retrieved 11 August 2010.
Bibliography
"Charting Louisiana" Edited by Alfred E. Lemmon, John T. Magill, and Jason R. Wiese; John R.
Hebert, consulting editor. Historic New Orleans Collection, 2003
"Geographies of New Orleans" by Richard Campanella, Center for Louisiana Studies, 2006
"History of New Orleans" by John Kendall. Lewis Publishing Company, 1922
"New Orleans The Making of an Urban Landscape" by Peirce F. Lewis. Second Edition, Center for
American Places, 2003

8. "Time and Place in New Orleans" by Richard Campanella. Pelican Publishing Company, 2002
"Transforming New Orleans and Its Environs" edited by Craig E. Colten. University of Pittsburgh
Press, 2000.
"An Unnatural Metropolis: Wresting New Orleans From Nature" by Craig E. Colten, Louisiana State
University Press, Baton Rouge, 2005
"Topical and Drainage Map of New Orleans and Surroundings From Recent Surveys and
Investigations, by T. S. Hardee, Civil Engineer. Thomas Sydenham Hardee, 1878
External links
Wikimedia Commons has media related to Drainage in New Orleans.
New Orleans: The Story of Three Great Public Utilities, 1914
History of New Orleans Drainage, 1718-1893 PDF
The Wood Screw Pump: A Study of the Drainage Development of New Orleans
New Orleans: A Wonderful Drainage System. Colliers Weekly, 1901
New Orleans Hurricane Risk
Public Health and Hurricanes: New Orleans Pilot Project
"Fix The Pumps" blog detailing post-Katrina repairs
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