It was a year ago, a sunny summer morning overlooking the Choptank River… We were discussing what it has all meant, studying the Chesapeake Bay for about 40 years with just retired University of Maryland scientists Walter Boynton and Michael Kemp.

Except they’re not sounding as retired as they should. Both have completed enviable careers; Walt’s dealing with leukemia and post-polio stuff, Mike with Parkinson’s disease. But like two old hounds, legs feeble but noses still keen, they’ve picked up the hot scent of a scientific mystery.

“Oligotrophication.” Mike almost doesn’t know how to pronounce it. It’s rarely uttered — the opposite of “eutrophication,” the term for the overfertilization and resulting de-oxygenation of waters through he addition of human wastes and fertilizers, which has become the sorry norm for the Bay and coastal waters around the planet for many decades.

Some oligotrophication would be a good thing for our Chesapeake, promising cleaner, clearer waters, lusher with all of the life that abounded when Walt first saw the Bay in 1969.

Could it be happening, even a smidgen, after 30-plus years of federal-state Bay restoration efforts?

Collegially, the two scientists go back and forth about the prospect, prodding, second guessing, arguing as they’ve done since they started working together in the 1970s — as scientists have done with one another since there was science.

With their younger colleague Jeremy Testa, they’ve recently uncovered tantalizing hints that the Chesapeake, decades after tipping over the edge toward a more degraded state, could be on the threshold of a comeback. “My gut says so, but [it’s] still just bits and pieces of proof…not conclusive,” Mike said.

Both men acknowledge that environmental science knows more about how ecosystems go to hell than about how they come back. There’s too little experience with the latter.

Walt’s more convinced at this point than Kemp. He recalled earlier work in the Potomac River where the water had gotten so cloudy that only a single species of nonnative grass inhabited the bottom. Visibility, measured by a black-and-white Secchi disc lowered into the river was 0.6 of a meter.

Visibility improved very marginally to where you could see another 0.05 of a meter into the water. But that was enough to explode the river bottom with many species of native grasses. Both scientists find it “thrilling,” this notion that there are “thresholds” or “tipping points” where a slight change can create a cascade of other changes.

They’re excited by what’s emerging from decades of old water quality data they’ve been reworking, reanalyzing “a thousand different ways” for the last few years, Mike said.

Something unanticipated seems to be happening, a trend involving forms of nitrogen — technically NH4, N2, N3 and NO2 — that might make you want to stop reading right here. But to a Bay scientist…well, let Mike tell you:

“When I first saw that relationship [in the data] I felt like the Conquistadors traveling across the American Southwest and coming upon the Grand Canyon — Wow! How’d this get here?”

In essence, it makes them suspect our modest gains in reducing nitrogen entering the Bay so far might have still been enough to reach a tipping point, creating a positive feedback loop, boosting the estuary’s ability to rid itself of pollution faster than expected.

Our traditional measurements of progress, like reductions in volumes and duration of oxygen-poor waters or total pollution entering the estuary, might not be the whole story, might not be accounting for the Bay, in effect, also beginning to help itself.

Walt and Mike were born to do just this stuff, to tease out scientific truths from big, complicated, ever-shifting ecosystems like the 187-mile-long Chesapeake, embedded at the base of 64,000 square miles of lands that drain into it through 40-odd significant rivers.

Both came here as Ph.D. students of the legendary H. T. Odum at the University of Florida, a genius who brought systems analysis to ecology, pioneered tracing the flows of energy through nature that allowed a fuller understanding of how all of the parts, including humans, fit together. Other scientists might publish on wetlands and fisheries; Odum delved into economics, physics, even religion and wrote books like Environment, Power and Society, which has influenced my own writing about the Chesapeake.

The pair’s Odumesque training would prove a good fit for the efforts begun in the 1970s to understand the estuary’s unprecedented, systemwide decline. Just as important from Odum, who worked his whole career with his even more famous brother, ecologist Eugene, Mike and Walt also learned collaboration, which was not encouraged in their field when they started.

Together, they’ve published around 50 peer-reviewed papers and in 2009 won the prestigious Odum Award for Lifetime Achievement, the only joint winners of the prize.

“We live in the age of estuaries,” the late oceanographer Donald Pritchard (an Odum winner) used to say, meaning the geologically brief times between Ice Ages when seas rise and Chesapeake Bays form.

More recently, in the last half century, we entered the age of eutrophic or polluted estuaries — more recently still the era of trying to reverse such trends.

Is it possible we may now be trending, slightly but surely, toward oligotrophic, or recovering estuaries?

It would be a fitting capstone to the careers of those two old dogs, Walter Boynton and Michael Kemp; both of whom would say more research needs to be done to confirm that.

The views expressed by columnists are not necessarily those of the Bay Journal.