Arden Hills is thinking about imposing a cap on how much of its land base can be consumed by its two expansion-minded private colleges.

The city has already imposed a one-year ban on any moves taken by higher education institutions after one of the colleges showed interest in a major facility that once housed Smiths Medical.

Now city officials are studying what they can legally do to corral the ambitions of Bethel University and the University of Northwestern-St. Paul, both four-year evangelical Christian schools with robust enrollment.

Most of the concern involves evidence that educational institutions do not provide the economic punch of a corporate firm like Smiths Medical when it comes to high-paying jobs per square foot. An underlying worry is a loss of tax base to tax-exempt religious institutions.

Northwestern said last fall that it wished to buy the building left behind when Smiths suddenly decided to move its corporate headquarters west to Hennepin County.

That announcement followed Bethel’s purchase of a 225,000-square-foot building once occupied by Countrywide Financial for what is now its Anderson Center, 1½ miles from its main campus.

Both Bethel and Northwestern “want to double their student population in five years,” City Planner Eric Zweber told planning commission members last week, as he presented the latest thinking of city staffers and City Council members on how to proceed.

One proposal, which drew a bit of pushback: capping higher education uses at 25 percent of one key zoning category. Zweber conceded that Bethel’s Anderson Center already consumes 23 percent of it, leaving little room for expansion.

Planning Commission Chair Roberta Thompson said she likes the idea of a limit, but as for 25 percent, “I’d have to think about that. I’m not sure how I feel.”

Arden Hills, she added, is a small community that runs the risk of having its most desired land base overwhelmed.

“You don’t want to be out of balance with no place to shop or eat,” she said.

City officials also are thinking of ensuring that certain uses, such as sports fields, happen on a core campus alone.

The city plans to meet with both schools, Zweber said. Its timeline for the next steps:

• In August, a draft policy ready to review with commissions;

• On Aug. 21, a City Council work session;

• On Sept. 6, a public hearing, with a planning commission recommendation later that month.

The City Council needs to act by October, when its moratorium on action by the colleges expires.

The Northwestern campus, which the school has occupied since 1972, rests in both Roseville and Arden Hills on Lake Johanna. It has about 3,400 students. Bethel, with 6,000 students, is on Valentine Lake in Arden Hills.