New flood plain maps ready soon

By Cherry Sokoloski
North Forty News

People who live along the Poudre and Big Thompson Rivers, or in other areas of the county prone to flooding, will have a chance to see Larimer County's new flood plain maps in early December.

The county will hold a public open house on Dec. 6, 6:30 p.m., in the commissioners' hearing room at the Courthouse Office Building. The public will have an opportunity to look at the revised flood plain maps and make comments pertaining to them. A 90-day public comment period begins Dec. 9.

The maps, called Flood Insurance Rate Maps, are used by lenders to determine which property owners need to buy flood insurance.

The county's flood plain maps were last changed in 1996. The new maps could go into effect by September 2006, after public review and approval by the local jurisdictions. The Larimer County Engineering Department is in charge of the mapping project.

Three stretches of river, one on the Poudre and two on the Big Thompson, were restudied this past summer prior to preparing the new maps. Mark Peterson, county engineer, said that some map changes can be expected in the areas that were restudied, and other areas could also see flood plain boundary changes due to more sophisticated mapping techniques.

The restudied areas are as follows: On the Poudre, from Shields Street upstream to Watson Lake; on the Big Thompson, from Marianna Butte Golf Course upstream about 2 miles to the confluence with Buckhorn Creek; and also on the Big Thompson, from the golf course downstream to County Road 9E, on the eastern edge of Loveland.

For these three areas, engineers used global positioning system technology to arrive at more accurate contours and elevations. As a result, the new maps should be "more up-to-date as to what the flood plain really looks like," according to Ed Woodward of the engineering department. Elevations on particular pieces of property and on the flood plain boundary at any given site should be more accurate, he said.

The Federal Emergency Management Agency will review the maps prior to the Dec. 6 meeting. FEMA will also digitize the maps this time around, so that people can go online to see if a given property is in a floodplain.

There are three different zones related to the flood plain, according to Woodward. They include the 100-year flood plain, the 500-year flood plain and the zone where no flooding or minimal flooding is anticipated. The engineers use hydrologic information from the various drainage basins in the county to determine flood plain zones.

New maps are not yet ready for the Little Thompson drainage area, since a study of the area is still under way. Those maps will be available for public review at a later date. All other flood plain areas of the county will have new maps in time for the open house.