As an environmentalist approaching 70, with peaceful coexistence between my species and the rest of nature still around the bend, I have wondered: Am I getting too old for this “saving the world” gig, tired of walking north on a southbound train?

Maybe I’m just not old enough. In the space of a single October week I was thoroughly inspirited by two gentlemen, one 90 and going strong, the other hard at it until the day he died recently at 88.

The late Michael Beer came from a cultured Hungarian family that fled the Nazis in 1939. He was a world-class scientist, an eminent Johns Hopkins biophysicist who built microscopes that could see atoms and envisioned half a century ago that we would someday (soon now) sequence genes by looking directly at the DNA.

The still vital Bernie Fowler was the only boy on Broomes Island, his little Patuxent River community, to go to high school. His family was warned that when a boy was big enough to see over the culling board it was time he went oystering. So much education would ruin him for work on the river.

Like Michael, Bernie had vision. He could see half a century ago that growth spreading downriver from the suburbia of central Maryland and Washington, DC, could overwhelm little, rural Calvert County.

He could also see that increasingly he couldn’t see his toes anymore when wading out in the seafood-rich grass flats of the lower Patuxent. Pollution from upstream sewage was murking the water, killing the grasses where Broomes Islanders had always netted softshell crabs.

He went into politics after his service overseas in World War II, serving as chairman of the Calvert County commissioners and later as an influential state senator. He set the tone for sane land use that serves the county to this day.

And he led a historic lawsuit by the lower river counties that forced Maryland and the EPA to fundamentally broaden their approach to cleaning up the river. The settlement became a template for the restoration of the whole Chesapeake.

Michael, like Bernie, was devoted to the part of the vast Chesapeake system that was his backyard—Stony Run and the Jones Falls, long-neglected, urban streams that run through Baltimore to the harbor and the Bay.

He lived there, between the Falls and the Hopkins campus for more than 50 years, planting native trees, leading schoolchildren on trash cleanups and nature walks and mobilizing students to stop development in the floodplains.

To raise awareness, he sponsored memorable kayak trips — persuading the city to open the dam at Lake Roland to flood the Jones Falls enough for a rollicking paddle through the urban heart of the city.

In retirement, Michael worked virtually full time to help restore Stony Run as a first-class park, an urban amenity for the dense city neighborhoods through which it flows. At 86, having moved to a retirement complex near his old home on the run, Michael set about getting a green roof of living vegetation planted there.

Bernie came this fall to speak to students at Salisbury University, where I teach. The Patuxent, he told them, by the 1990s was responding to all of the cleanup effort he inspired, but continued upstream growth ultimately outpaced pollution control. “It’s no better now than when I started working on it 45 years ago,” he said.

And a solution does not seem near, though the science is clear that the river can still respond, and quickly, if we do right by it. Had it not been for Bernie, that possibility might have vanished long ago.

Bernie said he’s accepted that clear water for the Patuxent, where he still leads annual “wade-ins,” won’t come to pass on his watch. “I remind myself Moses led the Israelites for 40 years in the wilderness and was not allowed to enter the Promised Land,” he said.

And he repeated Winston Churchill from World War II about “never give in…never, never, never, never.” hammering the words with Churchillian conviction.

Michael, too, knew huge work remained on the Jones Falls, and that Stony Run would never have the biological diversity of less-developed streams. He planted seedlings locally while his mind ranged globally to climate change and a world population grown beyond Earth’s capacity to sustain.

Such different men of different circumstances: Bernie, the country boy of deep religious faith; Michael the scientist and naturalist. They shared a selfless devotion to place, to tending where they lived, doing what they could, not waiting on the world to become gentler and kinder.

Perhaps it’s coincidence, but both struck me also with their long and deep relationships to their children, and to wives who shared fully in their long campaigns for nature.

These men of high accomplishment shared, too, a humility, a willingness to work for uncertain prospects neither would likely see. I badly miss the one, and treasure the other more and more.