The City Council in Elko New Market was nearing the final stages of commissioning an $8 million water treatment plant last fall when the word came down: The Metropolitan Council was proposing to drastically reduce the city's growth forecast.

A city that had once been projected to explode from roughly 4,000 people to more than 20,000 by the year 2030 was being ratcheted back to just 8,000 by 2040.

In an era when some small exurban towns have faced severe financial distress after investing in oversized infrastructure and then finding the growth didn't materialize, what was Elko New Market to do? The plant was sized for 10,000 people.

The final call: Stay the course.

"As a city we have some concern about assuming a radical change geographically in where people are going to want to live, based on several decades of a market existing for the type of housing we provide," said City Administrator Tom Terry.

"Will there be some changes in the future? Undoubtedly. But to the degree that the Met Council projections show, I don't know if that's entirely warranted. The reality is, they don't know for sure and neither do we. We need to take a temperate approach and see over time what the rate of change proves to be. Historically, the Met Council has significantly underestimated the growth in our community."

Last month the council issued revised projections bumping Elko New Market up to 12,200 by 2040. But that's still nowhere near the 2004 forecasts, which were made at a time when suburban and exurban growth rates were at their hottest.

Generally speaking, it's the farther-out communities that are concerned about projections feeling low, while those closer in have been concerned about too much development projected.

In Credit River Township, town board supervisor Brent Lawrence concedes that his community has hardly been a development hotbed lately.

"I don't think [we have] approved a new platted development in a long time, probably six years," he said.

Still, he said, the new projections call for only a relative handful of building permits annually over 30 years.

"Over time, that would mean a real slowing down. When you look at us and our proximity to Interstate 35, I think this might be low for us."

Belle Plaine has a mixed reaction to the new estimates.

The city is pleased to see the revised numbers after concerns of being reclassified by the council as a "rural center" when it was considered a "rural growth center" in the 2030 projections, a decade ago.

Community Development Director Chelsea Alger said the city invested time and money in planning for the growth based on the 2030 predictions and was concerned the council isn't considering outer communities as "developing."

The newest projections, although more encouraging, Alger said, are still short 3,000 people compared to the 2030 numbers.

Overall, the projections do represent a change from the last round in 2004, said the Met Council's Libby Starling, and that reflects a number of changes since then, notably in demographics.

"Development patterns are changing," she said, "and what's driving that is the demographics of the region. As we look at primary part of new household growth being senior citizen households, some of them will want to age in place while others will want to move to areas where they don't have to shovel as much snow.

"There simply are not enough people behind the boomers [in age] to replace those households."

What to do about water plant?

In Elko New Market, administrator Terry stresses that the city would not be creating a new treatment plant at all right now, given the growth uncertainties, were it not for the fact that there are problems with city water.

Not only is it rusty and hard, so that the vast majority of households have water softeners; some of it also bears traces of potentially harmful radium, so much so that state health officials have pressed for treated water.

"Radium is a naturally occurring element within deep bedrock wells," Terry said. "A lot of cities have it, but they also have water treatment facilities in place to improve quality — and the fringe benefit for them is elimination of radium."

The city, he adds, has taken a modest approach in sizing the plant for just a tiny fraction of the 80,000 people it expects to have in the distant future, given its proximity to I-35. It sought a site that could house multiple expansions years from now, assuming that growth comes to pass.

Still, it couldn't be a more glaring example of the uncertainties of future growth, considering that Elko New Market has by far the biggest reduction in growth prospects of any city in Scott or Dakota counties, whether measured by ­population numbers or percentages.

The decision on the size of the plant was made before the Met Council projections emerged, Terry said.

"We did have some discussions after they came out. But in the end they didn't have an impact. We identified a project that was large enough to be efficient and provide capacity for growth, but one that we could reasonably afford even under very conservative projections."

During the exurban land rush, Elko New Market — first two towns, then a merged entity — was one of the ­fastest-growing communities in the state. It multiplied several times over, from mere hamlets of just a few hundred people to 4,110 in 2010.

That was much less, though, than the 5,700 that the Met Council had expected by 2010, as the housing collapse and rising gas prices bit deeply into growth expectations.

Partly for environmental reasons, as there was danger to a pristine trout stream nearby, the Met Council brought costly sewer pipe out to Elko New Market during the growth spurt, making a major investment in a community that it then saw as a growth target.

During the boom, Elko New Market soared above 200 housing units added in a single year at its peak, 2003. By 2011, according to Met Council statistics, it was stagnant, with just four new units.

Today some exurbs are again seeing signs of life — notably Elko New Market. From four in 2011, the number of single-family homes started anew jumped to 27 in 2012 and to 40 in 2013, officials report.

Bottom line, Terry said:

"Regardless of any projections, we think we have growth potential. The market will determine what the growth actually is."