CalClim: California Climate Data Archive

CALIFORNIA CLIMATE WATCH
CURRENT ISSUE: August 2005

Read the full newsletter here: PDF format

Below Sea Level

By Laura Edwards
Western Regional Climate Center

Broken levees. Flooded homes and crops that lie below sea level. Sounds like some recent scenes in New Orleans and the Gulf Coast, but this is what can happen in California's Central Valley.

Figure 1. North side of Jones Tract levee breach, June 2004. Credit: DWR, http://wwwowe.water.ca.gov/newsreleases/2004/06-16-04floodpics.html

Recent hurricane-induced flooding in the Gulf Coast has had devastating effects on a now displaced population, and brought flood awareness to the forefront for local Californians. A report released in January by the Department of Water Resources (DWR) states the levees that protect hundreds of thousands of people below sea level and convey water for millions are "deteriorating, and in some places, literally washing away" [1]. The Delta's residents do not likely need to worry about hurricanes, but flood potential due to other weather events is high, in combination with poor levee construction and maintenance, changing climate effects, and the risk of earthquakes.

Sitting below sea level, Sacramento and other Central Valley cities are protected by a series of levees, similar to other metropolitan areas like New Orleans and the Netherlands. The recent DWR report addresses the flood risk that is present in the Central Valley, and suggested measures to remedy an ailing levee system in the Delta. Unfortunately, reductions in staff and funding to maintain 1600 miles of levees and other facilities have delayed necessary repairs. A Levee Review Board in 1998 and a separate report in December 2002 discuss the continued deterioration of the system that has occurred, and continues to occur, over several years.

With an increasing population comes increasing reliance on the levees' ability to control high water conditions. Recently, a planned community for 35,000 people has been approved for an area near Lathrop where Stewart Tract is now located. This is one example of the development that relies on levee protection. The current standard for flood protection is designing for a 100-year flood. The DWR report states that "during a typical 30-year mortgage period, there is a 26% chance that a homeowner living behind a levee will experience a flood larger than the 100-year flood." That is better chances than a major home fire, for which most homes are required to have insurance. The report also states concerns over the outdated floodplain maps that are currently used to assist developers and planners in the Delta.

The cost of repairing flood damage is high. The Upper Jones Tract levee breach that occurred on a dry day in June of 2004, is currently running a tab of about $100 million. It is estimated that levees maintained by DWR protect property valued at about $47 billion. The state is exposed to liability when levees fail, as was ruled in November 2003 in Paterno vs. State of California. The state was required to pay $45 million to 600 victims as a result.

The deferred maintenance, poor initial levee construction in the early 20th century, and development using decades old floodplain maps are just chapters in the story. A number of climate models show increasing sea level and different snowpack and snowmelt patterns in the coming decades and century. The amount and quality of water that flows into the delta will also have impacts on the demand for flood protection. In addition, earthquakes can destroy these earthen dams. And, as the flood of January 1997 showed us, just plain rain can create dozens of levee breaks and inundate thousands of acres and displace hundreds of thousands of people.

The good news is the Governor has appropriated more money this year for levee maintenance, but it is far from the billions of dollars DWR says is needed to bring this aging system up to date. The Governor has also called on the state's congressional delegation to seek more federal funds. The monies are sure to be put to good use, as there is a lot of work that needs to be done to improve this levee system that is in worse condition than those of New Orleans.

Figure 2. Jones Tract levee after repairs, August 24, 2004. Credit: DWR, http://www.publicaffairs.water.ca.gov/newsreleases/2004/08-26-04floodpics.cfm

References:

1. Department of Water Resources, 2005. Flood Warnings: Responding to California's Flood Crisis. http://www.publicaffairs.water.ca.gov/newsreleases/2005/01-10-05flood_warnings.pdf

2. Department of Water Resources, 2005. Flooded Islands Feasibility Study Baseline Report. http://baydeltaoffice.water.ca.gov/ndelta/floodedislands/index.cfm

3. Department of Water Resources, 1995. Sacramento-San Joaquin Delta Atlas. http://rubicon.water.ca.gov/delta_atlas.fdr/daindex.html

Page last updated 9/23/05.

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California Climate Watch Archive All data in the Climate Watch is provisional and subject to change. Please contact us for updated and quality-checked data. Jan 2005 [PDF] [Word] Feb 2005 [PDF] [Word] Mar 2005 [PDF] [Word] Apr 2005 [PDF] [Word] May 2005 [PDF] [Word] Jun 2005 [PDF] [Word] Jul 2005 [PDF] Aug 2005 [PDF] Sep 2005 [PDF] For 2004 stories, click here For 2005 stories, click here Monthly Weather Summaries 2005 2004	CALIFORNIA CLIMATE WATCH CURRENT ISSUE: August 2005 Read the full newsletter here: PDF format Below Sea Level By Laura Edwards Western Regional Climate Center Broken levees. Flooded homes and crops that lie below sea level. Sounds like some recent scenes in New Orleans and the Gulf Coast, but this is what can happen in California's Central Valley. Figure 1. North side of Jones Tract levee breach, June 2004. Credit: DWR, http://wwwowe.water.ca.gov/newsreleases/2004/06-16-04floodpics.html Recent hurricane-induced flooding in the Gulf Coast has had devastating effects on a now displaced population, and brought flood awareness to the forefront for local Californians. A report released in January by the Department of Water Resources (DWR) states the levees that protect hundreds of thousands of people below sea level and convey water for millions are "deteriorating, and in some places, literally washing away" [1]. The Delta's residents do not likely need to worry about hurricanes, but flood potential due to other weather events is high, in combination with poor levee construction and maintenance, changing climate effects, and the risk of earthquakes. Sitting below sea level, Sacramento and other Central Valley cities are protected by a series of levees, similar to other metropolitan areas like New Orleans and the Netherlands. The recent DWR report addresses the flood risk that is present in the Central Valley, and suggested measures to remedy an ailing levee system in the Delta. Unfortunately, reductions in staff and funding to maintain 1600 miles of levees and other facilities have delayed necessary repairs. A Levee Review Board in 1998 and a separate report in December 2002 discuss the continued deterioration of the system that has occurred, and continues to occur, over several years. With an increasing population comes increasing reliance on the levees' ability to control high water conditions. Recently, a planned community for 35,000 people has been approved for an area near Lathrop where Stewart Tract is now located. This is one example of the development that relies on levee protection. The current standard for flood protection is designing for a 100-year flood. The DWR report states that "during a typical 30-year mortgage period, there is a 26% chance that a homeowner living behind a levee will experience a flood larger than the 100-year flood." That is better chances than a major home fire, for which most homes are required to have insurance. The report also states concerns over the outdated floodplain maps that are currently used to assist developers and planners in the Delta. The cost of repairing flood damage is high. The Upper Jones Tract levee breach that occurred on a dry day in June of 2004, is currently running a tab of about $100 million. It is estimated that levees maintained by DWR protect property valued at about $47 billion. The state is exposed to liability when levees fail, as was ruled in November 2003 in Paterno vs. State of California. The state was required to pay $45 million to 600 victims as a result. The deferred maintenance, poor initial levee construction in the early 20th century, and development using decades old floodplain maps are just chapters in the story. A number of climate models show increasing sea level and different snowpack and snowmelt patterns in the coming decades and century. The amount and quality of water that flows into the delta will also have impacts on the demand for flood protection. In addition, earthquakes can destroy these earthen dams. And, as the flood of January 1997 showed us, just plain rain can create dozens of levee breaks and inundate thousands of acres and displace hundreds of thousands of people. The good news is the Governor has appropriated more money this year for levee maintenance, but it is far from the billions of dollars DWR says is needed to bring this aging system up to date. The Governor has also called on the state's congressional delegation to seek more federal funds. The monies are sure to be put to good use, as there is a lot of work that needs to be done to improve this levee system that is in worse condition than those of New Orleans. Figure 2. Jones Tract levee after repairs, August 24, 2004. Credit: DWR, http://www.publicaffairs.water.ca.gov/newsreleases/2004/08-26-04floodpics.cfm References: 1. Department of Water Resources, 2005. Flood Warnings: Responding to California's Flood Crisis. http://www.publicaffairs.water.ca.gov/newsreleases/2005/01-10-05flood_warnings.pdf 2. Department of Water Resources, 2005. Flooded Islands Feasibility Study Baseline Report. http://baydeltaoffice.water.ca.gov/ndelta/floodedislands/index.cfm 3. Department of Water Resources, 1995. Sacramento-San Joaquin Delta Atlas. http://rubicon.water.ca.gov/delta_atlas.fdr/daindex.html Page last updated 9/23/05.