For the first time in over 20 years Yavapai County is reviewing and remapping the Verde Valley's floodplains.
The $500,000 project, set to begin shortly after the first of the year, will update the maps originally made in the early 1980s and fine tune some of the data used to determine what low-lying areas are susceptible to flooding and what areas are not.
The county uses the maps to regulate construction within the floodplain boundaries. But the average resident of the floodplain areas knows the maps as the determining factor in whether they need to pay for federal flood insurance and how much.
The maps are known as Flood Insurance Risk Maps and are ultimately approved by the Federal Emergency Management Administration.
"It's not a flood risk map so much as it is a flood insurance rate map," said Charlie Cave, project engineer with the Yavapai County Flood Control District.
"They were a result of the national flood insurance program that began in the late 1970s. But they also provide us with a lot of other useful information that we need to carry out our administered duties."
Cave says that some of the data used in the original maps is outdated and that newer and better techniques can now be applied to better delineate the floodplain boundaries.
"There are areas where we know the current FEMA maps are wrong. We know of areas that regularly have water on them but don't show on the map," Cave said. "Some of the earlier determinations were done rather rudimentary."
However, Cave said the district does not expect to see any drastic changes.
"We don't believe there will be any huge areas that will go into the floodplain or come out of the floodplain. The focus of the effort is to use newer methodology, to use the newer mapping we flew a year and a half ago, and just kind of perfect the map a bit," Cave said.
Most of the corrections, Cave believes, will be along the edges of the flood plain and will result from newer and better digital methods for determining the subtle details in the land contours.
"There has also been some evolution in the water course. The river meanders and changes over time," Cave said.
Cave expects the project, which is funded for the current fiscal year, will go to bid in early 2009. And take 18 months for the new maps to be approved.
"Once the engineering is done and the draft maps created there will be a period of public comment. Then it will go to FEMA, which will take four to eight months to be approved," he said.
Clarkdale and Camp Verde contract with the Yavapai County Flood Control District for their floodplain management. Cottonwood does its own.