Pueblo: Levee system and new FEMA floodplain map

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Here’s the lowdown on planning for upgrades and certification of the levee system in Pueblo, from Chris Woodka writing for the Pueblo Chieftain. From the article:

After Hurricane Katrina in 2005, FEMA began a nationwide effort to reassess the effectiveness of levees. In Pueblo, levees were built on the Arkansas River and Wild Horse Dry Creek in 1926, while the Fountain Creek levees were built in the 1980s. While the Fountain Creek levees might be more susceptible to actual flooding, it has been more difficult to certify the Arkansas River system because it is more than 80 years old and much of the original engineering data is missing.

There’s also a communication problem. “Our big concern is that they are so determined to meet their deadline rather than be accurate,” said Gus Sandstrom, president of the Pueblo Conservancy District that owns and manages the Arkansas River levees. “Three months ago, we were told there would be only one national standard.” Sandstrom explained that the district has tried, with little success, to convince FEMA that the standards for levees on Western rivers that are prone to flash flooding should be different from those for levees in hurricane zones. In addition, the district and FEMA disagree on the potential high-water mark and effectiveness of some of the levees…

The problems on Fountain Creek have been addressed in an Army Corps of Engineers study completed last year, which found that levees are not sufficient to contain the freeboard – basically, waves above the high-water mark – in a 100-year flood. A combination of capping an existing levee, removal of obstructive vegetation, proposed dredging and stabilization projects are being used to address the problem.

The Arkansas River is largely protected by Pueblo Dam, which holds back flood water and has operating criteria that call for shutting down release gates if flows on the river reach a certain point – 6,000 cubic feet per second or greater at Avondale. The levees along the river that have become a canvas for local artists are designed to contain far greater floods of up to 120,000 cfs. FEMA’s position is that the dam might not be closed in time during 100-year floods. “They use a very conservative approach,” [Dennis Maroney, Pueblo stormwater director] said.

The concern for the city, at least in terms of what shows up on future FEMA maps, is the earthen levee on Wild Horse Dry Creek north of 11th Street, Maroney said. The levee is badly eroded, yet well above the base elevation of the creek. However, if it is not certified, FEMA’s maps would omit it. In addition, FEMA wants guarantees that culverts on the 18th Street bridge will be maintained, and its maps do not include railroad beds that channel water as physical structures.

The result of all those factors could be that the historic flood plain that includes much of Downtown Pueblo could be listed as unprotected by levees. That could mean that Downtown property owners could be required to obtain flood insurance, but it would not mean an end to future development or the city’s ability to finance projects, city attorneys said. City ordinances were rewritten in 2005 to restrict development in flood plains and areas of special flood hazard, said Tom Florczak, assistant city attorney. The city allows development that does not restrict flows or encroach on floodways and that is constructed so that buildings would not suffer flood damage, Florczak said.

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