As Stanford University advances its request to add more than 2 million square feet of academic space to its campus by 2035, one question that has long bedeviled local residents and policymakers is: How big can the university get?

Now, there is an answer. According to a study commissioned by Santa Clara County planners, the university can roughly triple its density and expand to 44 million square feet. Currently, the university has 15.2 million square feet of development. Furthermore, the study concluded that Stanford has enough space on its academic campus to accommodate such a level of growth without infringing on the foothills.

Known as the Sustainable Development Study Supplement, the new analysis aims to address a question that's been posed by Palo Alto council members, Santa Clara County supervisors and concerned residents, more than 500 of whom signed a petition last December demanding that the county establish a "maximum buildout" on Stanford.

"Stanford cannot continue to grow indefinitely without seriously compromising our quality of life on the Peninsula," states the petition, which was launched by former Palo Alto Mayor Peter Drekmeier.

The county Board of Supervisors expected the university to address the question of "maximum build-out" in 2000, when it approved Stanford's last application for a General Use Permit (GUP). As part of the approval, the county required Stanford to submit a Sustainable Development Study that would "identify the maximum planned buildout potential for all of Stanford's unincorporated Santa Clara County land" and identify the university's strategies for preventing sprawl into the hillsides.

Instead, Stanford submitted a study that considered three theoretical growth scenarios -- with low-, moderate- and high growth -- with a 2035 horizon (despite some misgivings, the supervisors approved the study in 2009 by a 3-2 vote).

Joe Simitian, president of the Board of Supervisors, said the new supplement was commissioned by county staff as part of the board's ongoing review of the new GUP application, a process that is expected to conclude by March 2019. Simitian told the Weekly that in commissioning the study, county officials were hoping to get Stanford to answer the question posed two decades ago.

"Then as now, people were asking, 'Is there an end to this and, if so, at what point? Or are we going to expect that every 15 years or so, the university will come back to ask for another few million square feet?" said Simitian, who was also on the board in 2000, when the existing GUP was approved.

The study's conclusion is based on existing land use designations, land capacity, development patterns at other universities and various resource constraints (energy, water and transportation). The study used a classification tool created by the Carnegie Commission of Higher Education to find 27 universities categorized as comparable to Stanford -- a list that includes University of Michigan-Ann Arbor, Northwestern University and -- closer to home -- UCLA and UC Berkeley. After evaluating the floor area ratio (FAR) on each campus (a measure of density), it concluded that Stanford has a "relatively low development density" and "one of the largest acreages across comparable universities."

Not surprisingly, the survey of universities showed that those with less land generally tend to build at a greater density. Universities with lower density than Stanford -- including UC San Diego, University of Colorado, at Boulder, and Yale University -- all have more than 1,000 acres of developable land and FAR of under 0.3 (Stanford has 1,018 acres on its academic campus).

Those on the higher end of the density spectrum -- including Johns Hopkins University, Boston College and Massachusetts Institute of Technology -- all have less than 200 developable acres and FAR levels greater than 0.9.

Stanford's 1,018-acre academic campus currently has a FAR of 0.34, though it is slated to go up to 0.38 once the university completes construction of the Escondido Village Graduate Residences and to 0.46 once the university fully implements the construction plans in its new General Use Permit.

Even with this expected growth spurt, the study suggests that Stanford can potentially accommodate much more. It acknowledges that Stanford is unlikely to ever reach an FAR of 1.5, which is generally associated with "very small campuses in highly urbanized cores of major cities (New York, Boston and Washington, D.C.)."

It does, however, deem a FAR of 1.0 to be a more reasonable "maximum" density to plan for. If Stanford were to reach for that density level (which would still be a bit below Berkley's FAR of 1.11), its academic campus would accommodate 44.4 million square feet of development.

Even at a more modest a FAR of 0.75, Stanford could accommodate 33.3 million square feet of development, effectively doubling its campus.

To be sure, there's been no sign to date that Stanford wants to go that route, a fact that Stanford officials had emphasized in a fact sheet released Tuesday. The current General Use Permit application requests permission to build 2.275 million square feet of academic space and 3,150 new housing units or student beds by 2035.

Stanford noted that the new report's study horizon is "beyond a reasonable planning frame" and that its conclusions are on "hypothetical development capacity."

"It is not possible to know what the needs of the university and the community will be in the future," Stanford response stated. "Land use is a dynamic and rapidly-evolving field being shaped by advances in knowledge and technology. And given the rapid rate of economic and societal change in the world, the work done by Stanford is likely to continue evolving in the coming decades as new needs and opportunities emerge for the research and teaching missions of the university."

The report also recognizes its own forecasting limitations. Five decades, it notes, is the typical limit of anyone's ability to accurately predict future development and land use patterns. Most General Plans look only about two or three decades into the future. At current rates of development, doubling Stanford's density would take at least 50 years and possibly more than a century, "well beyond the planning horizon for even the most long-range plans."

"Extrapolating the present to the distant future through the lens of the current environment is invariably uncertain and speculative," the plan states.

Of the various development constraints that the study considers (including energy, wastewater, solid waste), water usage is deemed among the most significant. In the absence of a drought, projects that supply of potable water would become a constraint once total campus development grows from its current level of about 15.2 million square feet to about 25.4 million square feet. With drought conditions, water supply would become a constraint when campus reaches 21 million square feet.

Traffic and transit can also become a constraint, the study states, though not necessarily an insurmountable one. The study notes that there are various transit improvements being implemented throughout the region ("with varying success"); that technological innovations (including autonomous vehicles) can potentially increase roadway capacity; and that Stanford is pursuing its own congestion-management programs as part of its efforts to comply with a "No Net New Commute Trip" policy in its General Use Permit.

"Transportation conditions in and of themselves do not represent a physical constraint to development on the Stanford campus," the study concludes. "Rather, the acceptability of levels of congestion, and the comfort and convenience of different modes of travel are the real constraints. Societal norms related to these factors have and likely will continue to evolve over time. It is unknown to what extent the surrounding community could accept higher congestion levels and whether social norms would represent a future constraint to campus growth."