Feds changing Lake Travis flood maps
Changes will affect hundreds of buildings and 3.2 square miles of property
Matt Rourke/AMERICAN-STATESMAN
(enlarge photo)
This is an aerial view of homes along the shores of Lake Travis. Unknown what elevation this is. Some structures are built on stilts.
By Marty Toohey
AMERICAN-STATESMAN STAFF
Friday, March 18, 2005
A change made to the federal government's flood maps will affect hundreds of properties along Lake Travis, raising insurance rates and creating new restrictions for building or modifying houses.
The change comes as the Federal Emergency Management Agency updates its flood maps for the lower Colorado River. The new FEMA maps will show that Lake Travis fills to higher levels during a flood than previously thought. The maps will also show that about 550 buildings face a greater risk of flooding.
"Not many people know this is coming," said Bill McCann, a spokesman for the Lower Colorado River Authority, which manages Lake Travis.
Local, state and federal officials are worried that property owners along "flash flood alley" could be caught unaware by the change. The new flood maps will be presented in September, and will be fully implemented in early 2006. Simple steps could save property owners time, money and hassle, officials say.
The federal change will send towns along Lake Travis scrambling to modify their own rules. One choice those communities will face: integrate the new maps into their own laws — and accept the insurance-rate hikes — or lose all flood insurance and federal aid following a disaster.
"That's really no choice at all," Lago Vista Mayor Dennis Jones said at a recent City Council meeting. "How do you say no to that?"
The chain of events leading to the change started in the 1990s. The lower Colorado was flooding differently and more frequently than available data said it should. The flood maps in Travis County were obviously faulty, the result of imprecise surveying common in the 1970s.
With suburbs sprouting along Lake Travis, more lives and property were at stake. Many of those new residents were only dimly aware of the lake's true function, which is to control floods that could threaten Austin and other downriver communities.
In 1999 the Lower Colorado River Authority and the Army Corps of Engineers agreed to conduct a comprehensive study and create more accurate maps. Travis County, the City of Austin and several other communities also pitched in money for the $16 million project.
The study is ongoing. But nearly three years ago it reached a significant conclusion: a major flood on Lake Travis will probably waterlog more property than previously thought.
The actual odds of being flooded have not changed. There is no change in the way the dams are operated. Water levels are not likely to be higher now than they were 10 or 20 years ago. It is, say flood-plain experts, simply that the old maps were wrong.
As the Army Corps reached this conclusion, FEMA decided to update flood maps nationwide. The federal agency will use the Army Corps study to draw new maps of the Lake Travis area.
FEMA will present the new maps to Lake Travis communities in September. A 90-day appeal period will begin in December. Once the appeals are resolved, the maps will be implemented.
One change will be a raised "100-year flood plain," which in turn will affect insurance rates and building codes.
Flood maps are based on probabilities. One benchmark is the "100-year flood," which experts say has a 1 percent chance of happening in any year. Such a flood would raise Lake Travis to 716 feet above sea level, according to current federal maps.
Those living in a 100-year flood plain must purchase federal flood insurance for the government to back their mortgages. They typically pay higher rates, because of their higher risk.
Many communities also restrict building in the flood plain. In unincorporated Travis County, for example, such land cannot be used for large-scale housing developments.
Lake Travis, in its sixty-plus years, has never experienced a 100-year flood, according to the Lower Colorado River Authority. Its highest level was 710 feet above sea level, on Dec. 27, 1991. Its normal water level is 681 feet.
But experts warn that sooner or later the lake will experience a 100-year flood, an event estimated to cause $192 million in damage in Travis County alone.
Unfortunately for those living just above the flood plain, the Army Corps found that a 100-year flood would actually raise Lake Travis to 722 feet above sea level, not 716. FEMA's maps will, in turn, mark the new flood plain at 722 feet.
When the maps are changed, about 3.2 square miles of total property ringing Lake Travis will be reclassified as part of the flood plain, according to data from the Lower Colorado River Authority.
Much of that land is prime real estate.
Lago Vista and Lakeway, two lakeside communities with gently sloping waterfront property, have quietly been notifying building-permit applicants of the upcoming changes.
"If people aren't paying attention," said Jones, the Lago Vista mayor, "there are some things that could definitely catch them off guard."
For property owners
The federal government plans to raise the flood plain along Lake Travis from 716 above sea level to 722 feet. This will make about 550 buildings and numerous other properties subject to higher flood-insurance rates and stricter building regulations. Officials say simple measures, like the following, could prevent big headaches for property owners along the lake:
1. Know your property's elevation. Even non-lakefront homes may fall into the new flood plain.
2. Buy flood insurance as soon as possible if your house sits between 716 and 722 feet above sea level. If you wait until the federal government officially raises the flood plain to 722 feet, you will almost certainly pay significantly more for the insurance.
3. Check whether a property falls into the new flood plain before buying. Sellers are not required to notify buyers if a property will fall into the new flood plain.
4. Be aware that Lake Travis was designed as a reservoir and flood-control device, not a residential attraction. Its function is to protect Austin and other downriver communities, not the houses built along its banks.
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