SIOUX FALLS - People and organizations that use telephone polls face the prospect that 11 percent of the population is unreachable because they use cell phones only.

Those people are not in the directories that pollsters use to line up the samples they need in their surveys.

"This is a problem a lot of people are starting to worry about," said Dusty Johnson, chairman of the South Dakota Public Utilities Commission. "For political candidates running for office and nonprofit agencies trying to raise money and polling agencies, this is an issue."

The Sioux Falls School District is paying $9,000 for a telephone poll to see how the public perceives public schools.

Superintendent Pam Homan said she recognized the cell phone problem but said a phone survey beats the other choices. The district ran a similar phone survey two years ago but does others by mail requiring someone to fill out a form and return it.

"I do know from the past many years of surveying that when you go paper and pencil, your response rate is so low that we don't have anything we can project," she told the school board.

Johnson said South Dakota has about 415,000 wire phone lines in homes and businesses and 515,000 wireless phones.