A new report from the Delaware Population Consortium shows growth is expected to slow in Kent County following several years of rapid expansion and building.

    The consortium’s annual population projections, released last month, also predict the state’s total population could top 1 million by 2025.

    Among other factors, the booming housing market caused Kent County’s population to grow by 13% percent from 2003 to 2008, said Ed Ratledge, director of the Center for Applied Demography and Survey Research at the University of Delaware and a member of the consortium.

    But the report projects the county’s population only will grow approximately 8% from 2008 to 2015.

    Figures are similar for the city of Dover, where population grew by 9.6% from 2003 to 2008 and where it is expected to grow by roughly half that amount through 2015. Right now the city has approximately 36,300 residents, according to the report.

    The projections are invaluable to the city’s government, which uses the data when considering housing projects, infrastructure needs and school construction recommendations.

    Dover city planner Janelle Cornwell, who also chairs the consortium, said the projections are a good thing for the city and that slower growth will take some strain off municipal resources.

    “In the last couple of years we were growing at higher rates than we’ve normally been growing, now we’re going to see a little bit of a slowdown,” she said. “We knew the population was going to peak at one point; we couldn’t handle the fast growth.”

    Since the data used to make the projections were based in part on real numbers, the slowdown is already underway, explained Mike Mahaffie, a planner with the state Office of Management and Budget, and a member of the consortium.

    “The projections reflect changes in the data, so from a very technical standpoint the input that were receiving has shown a slow down,” he said. “A lot of it’s going to [depend on] what’s the current number of building permits, how does it compare to previous building permits.”

    Overall, Cornwell said, the projections show Dover will maintain a solid population in the coming years.

    “I think we were happy to see the numbers showed that we’ve had some good growth, the population is over 36,000, which is good. We’re continuing to grow, which is a good thing. We don’t see any decrease in population, which is also good.”

    Cornwell said the projections also are useful in the city’s long-term planning efforts.

    “We actually were able to take these numbers and put them into our draft Comprehensive Plan,” she said. “We use them to determine, if we have a large number of older people, do we need more senior housing or do we need less of that? Do we have the right type of housing that we’re going to need, the right kind of infrastructure?”

    The final draft of the city’s 2008 Comprehensive Plan will be presented to the Dover Planning Commission and the public at a special meeting Tuesday, Dec. 2. The city council will vote on the plan later next month.

    Ratledge said the consortium’s projections consider a variety of data from private and public institutions and also rely heavily on the eyes and ears of consortium members, who represent a wide range of state agencies, local governments and research concerns.

    The projections, he said, begin with an analysis of confirmed, concrete data.

    “There are three basic components of any projection. We always start with the latest census, 2000 in this case, then we’re looking at things like the fertility rates and mortality rates,” he said. “We can get that stuff down very accurately.”

    But after that, things get a little trickier.

    “Then we go looking at another factor, migration. That’s always the most difficult part,” he said.

    Migration refers to the portion of the population that comes into or leaves the area from year to year. Migration can be tough to pin down, Ratledge said, because it depends on a whole new set of factors and indicators.

    Job opportunity drives migration most, and by examining data from the Internal Revenue Service and the U.S. Citizen and Immigration Services office, as well as business development figures from local governments, the consortium can make a pretty good estimation of migration in and out of a given area, Ratledge said.

    Hard numbers are fed into roughly 20 computer spreadsheets, which synthesize some of the data, but the process for formulating the projections is far from automated.

    “We don’t actually have to take all that [data] at face value if it disagrees with what we know on the ground,” Ratledge said. “We look at things like building permits, actual construction that takes place; that information is supplied by members of the consortium from planning agencies, everybody contributes what they see going on the ground right now.”

    When the raw data are combined with these on-the-ground perspectives, it can make for pretty accurate projections.

    Ratledge looks for a margin of error of about plus or minus 3% in the consortium’s 10-year projections, but they’ve done better than that since the consortium was founded in 1975.

    “One time we came in with Kent [County] within one person from what we forecasted 10 years out,” he said. “In 1990 we were actually more accurate than the Census Bureau was.

    “Our motto is: ‘Project Often.’ That’s why we do it every year.”

Email Doug Denison at doug.denison@doverpost.com