When Brendan Murphy faced the prospect of choosing his individual graduate challenge — a prerequisite for all seniors at Hinesburg's Champlain Valley Union High School — he suggested perfecting a recipe for barbecued pulled pork. His father was underwhelmed by the idea. As other CVU students were learning new musical instruments and volunteering with local nonprofits for their senior projects, Murphy's dad, Liam, urged his son to take on something "a little more ambitious," especially because his college applications were on the line.

The younger Murphy rose to the challenge. A few months after embarking on the project, he presented the findings of his research on Lake Champlain's changing water levels not just to his fellow CVU students, faculty and parents, but also to members of the Vermont Geological Society. Some of them were keenly interested in the young man's work.

Murphy demonstrated what many Vermonters living along the lake have casually observed for years, but no researcher had quantified in four decades: The water levels of Lake Champlain — including its average lows and highs and its mean — are higher than previous measurements would suggest. Since the early 1970s, the lake has been slowly but steadily rising.

It's easy to jump to the conclusion that global warming is to blame, but Murphy suggests that climate change actually plays a modest role at best. He theorizes that a "confluence of factors," both natural and related to human activity, are causing the lake to rise. Those factors range from the retreat of the glaciers beginning 15,000 years ago to the proliferation of new roads, parking lots and other impermeable surfaces that speed the flow of rivers and streams.