Hanover — The vast majority of Dartmouth College alumni met the idea of expanding undergraduate enrollment with skepticism or outright opposition, according to a recently released internal report.

The Presidential Task Force on Enrollment Expansion this week released its research on the prospect of increasing the undergraduate student body by up to 25 percent, or 1,100 students — a move that college President Phil Hanlon said could allow for more diverse classes, economies of scale and an increase in Dartmouth’s influence in the world.

Hanlon and the college’s board of trustees elected not to pursue expansion after receiving the task force’s report, which outlined a lengthy, complex process for the college to follow in order to grow, and also recommended that administrators meet existing infrastructure needs first.

“The trustees ultimately decided, based on my recommendation, that the undergraduate student body should remain at its current level,” Hanlon said in a Tuesday letter to the Dartmouth community. “Both my recommendation and the subsequent decision by the trustees were informed by this report, which will continue to serve as a valuable tool for any future considerations of enrollment scale.”

Starting in August, the task force compiled nearly 800 alumni responses to the idea and found that 75 percent of those polled were what the task force deemed “skeptical.” Another 9 percent were “categorically” against the idea, with about 14 percent in favor and a sliver undecided.

The task force, which comprised faculty, administrators and a trustee, created projections of how many extra faculty members, staff members and dorms various student increases would require. The full 25 percent expansion would mean roughly 160 more faculty members, more than two-thirds of them tenure track.

But the researchers did not supply Hanlon with hard numbers for the likely cost of each option. Mark McPeek, a professor of biology and a task force member, said the problem was too complex and too sensitive to long-term economic change to make such predictions.

In 10 to 20 years, “who knows what’s going to happen to the economy, to the cost of various things?” he said in an interview. “It just didn’t seem feasible.”

The task force found that economies of scale — ways of saving money through growth — were unlikely. Costs associated with extra students grow in a linear way, he said, or at an even greater rate in some cases.

“Every one of them needs a dorm room. Every one of them needs a seat in the cafeteria,” he said, adding that the same applied to academic support, health services and a host of other amenities.

The enrollment report also questioned whether enrollment growth would bring academic or demographic diversity to the student body, especially given that the Admissions Office already is showing results in achieving those goals without an expansion.

“It may be that crafting a diverse class is more easily achieved with a larger class size; however, enlargement is neither necessary nor sufficient for it,” the report said, in part.

Dennis Kaufman, a 1966 graduate who lives in Norwich and is active in the area’s Dartmouth alumni group, offered both an alumnus’ and a resident’s perspective on expansion.

He harked back to the changes that came to the area in the late 1960s, when the interstates were completed, and the early 1970s, when the college expanded to admit women.

Although Kaufman did not oppose either change, he said they contributed to transportation problems that the region still faces.

“The interstate exit required infrastructure changes that there was simply not enough room for either in Hanover or Norwich to accommodate,” he said in an email. “In Hanover, the traffic backlog at Main and Wheelock is a fact of life and relief from a public transportation system is simply lacking, and in Norwich, we are perennially trying to decide what to do with the land along the roads that approach the Interstate exit.

“So am I opposed to a population increase of nearly 25 percent in the Dartmouth population (students and staff and professors to serve the student increase)? Yes, but not for nostalgic reasons, but rather for the things left undone dating back to the 1960s.”

The task force made a similar point about infrastructure needs left unmet, noting that the college needed to “modernize and expand existing classrooms, faculty offices and academic gathering spaces,” as well as dorms, parking and other areas.

Changes of this magnitude would require careful planning, the report said, which would mean a step-by-step process spanning as long as a decade and drawing funding from as many as two capital campaigns.

In his community letter, Hanlon highlighted some ongoing efforts to meet those infrastructure needs, including plans for new dorms, new parking on the north side of campus, and a $1.5 million annual increase to the budget for facilities renewal.

“This is a period of historic investment in meeting current campus needs and pursuing bold ambitions for the future of Dartmouth,” he said.

Rob Wolfe can be reached at rwolfe@vnews.com or 603-727-3242.