Floodplain flap is likely over

SANDPOINT — A convoluted controversy surrounding a waterfront home thought to be in violation of Bonner County’s floodplain ordinance is expected to come to an anticlimactic end today.

County commissioners are scheduled to take up a proposed variance from a floodplain development standard by landowners who expanded their home without a permit. But the homeowners no longer need the variance because a new survey found the home is actually two-tenths of a foot above the base flood elevation of Lake Pend Oreille.

A previous survey done on Dwight and Pamela Sheffler’s home indicated the top of the bottom floor was nine-tenths of a foot below base flood, which meant the home was not in compliance with the floodplain standard.

However, the two surveys are basically identical. They appear to be different because of a change in the datum, the federally established set of reference points that were used to determine the home’s elevation.

The original survey done by Glahe & Associates indicated the home intruded slightly into the floodplain. That determination was based on the most recent floodplain map available at the time, although that map utilized datum from 1929.

The new survey, conducted by Tucker, Brown & Vermeer, certified the home’s elevation as being slightly above the base flood elevation. The latter survey, however, utilizes more precise datum from 1988.

The older datum put the lake’s base flood elevation at 2,071 feet, while the newer datum raised that elevation an average of 3.87 feet, according to Planning Director Clare Marley.

When the datum conversion factor of 3.87 feet is added to the original survey elevation, it almost perfectly matches the elevation certified in the newer survey.

“They were very, very close to the same. The only difference, ultimately, was the difference between the old map and the new map, and he’s entitled to the new map,” Marley said.

Some are suspicious of a newer survey producing a more favorable result for the landowners, but Marley said the numbers check out and the home has been proven to be in compliance.

When the datum conversion factor is added to the elevation in the Glahe survey, it puts the home at 2,073.97 feet. The Tucker survey put the home at 2,073.9 feet.

“I double checked that four, five times just to make sure that we were correct,” added Larry Glahe.

Another layer of confusion to the issue emerges when you apply the datum conversion factor to the older base flood elevation of 2,071 feet, which produces an elevation of 2,074.87.

But the newer flood maps from the Federal Emergency Management Agency list the lake’s base flood elevation as 2,074 feet. Marley said she is working with the agency to determine why there’s a discrepancy of nearly a foot.