It was the best day I would spend in a “classroom,” drifting through the summer wetlands of the Patuxent River as the “professor” stood tall in his canoe, informing his floating gaggle of schoolchildren about plankton, fish and the food web; of birds that had flown across the continent to harvest the swelling crops of seed from the tidal marsh; and the joy and wonder of how it all fit into the greater Chesapeake ecosystem.

That was some 40 years ago, and John Page Williams was already the iconic educator for the Chesapeake Bay Foundation. The methods he perfected in those old aluminum canoes are still emulated throughout the Bay region and beyond.

“He was hands-on — on the water, in the water, in small boats,” recalled Don Baugh, who would later lead the foundation’s outdoor programs. “All that became a standard that was replicated around the Bay and eventually incorporated in national programs, like NOAA’s Meaningful Watershed Educational Experiences.”

That day on the Patuxent, John Page was also training a young educator not long out of college, Cindy Dunn. “He taught me [that] “being a girl” was no excuse for not loading 75-pound canoes onto the trailer,” said Dunn, who is now Pennsylvania’s Secretary of Conservation and Natural Resources and is still paddling her native Susquehanna.

When I heard John Page would be retiring, I suggested an interview at his office at the Bay Foundation’s headquarters. Silly thought.

“Meet me at the boat ramp,” he said.

It’s been nearly half a century since the young Princeton graduate from Virginia got a $10 membership in the foundation for a birthday present.

Environmental education wasn’t the first direction he’d considered back then. He did a couple years in a seminary after college. “But I just couldn’t stay off the water,” he said.

By 1973, he’d been hired as the foundation’s first environmental educator. The nonprofit organization, begun in 1967, had only a couple of thousand members then (compared with more than 200,000 now) and didn’t own a vehicle, so John Page hauled its eight canoes in his own pickup, reimbursed at 10 cents a mile.

On a sultry morning this summer, we met at a creek of the Severn River just north of the U.S. 50 bridge. John

Page was towing the same 17-foot Whaler he’s used since 1993 to explore virtually every river and creek of the Chesapeake.

He loaded aboard rods and reels, nets, oxygen meters and more, tools to see the Severn through many lenses, in search of everything from white perch to dead zones. Half an hour later the boat was still on the ramp as its captain prowled the shoreline for grass shrimp, poking at the gravelly bottom and marshy fringes, all along commenting on the state of the river (underwater grasses good, pickerel terrible, oysters — it depends).

I expected no less from a man who opened his lovely 1993 book, Exploring the Chesapeake in Small Boats, with this: “[W]e did not have a destination in mind, and a quick trip was not our intention.”

He also advised readers to “pick one area and spend some time exploring it.” And he has done just that for 46 years now, progging about this roughly 5-mile stretch of the Severn near his home. No fish nor great blue heron is more intimate here.

We cruised over catfish on the depth finder, which soon showed a little “lump” that John Page discovered years ago, a slight rise in the bottom 25 feet down. On a hunch, he got the Bay Foundation to partner with other groups to place concrete “reef balls” on the lump — which was always plagued by low-oxygen water in the summer but can yield big, 13– to 14-inch white perch when fall temperatures bring better water quality.

He knew another deep spot where sunken railroad timbers down by the U.S. Naval Academy create enough turbulence as the tide moves in and out to oxygenate the bottom — at nearly three times the level found on the upper lump.

The reef balls might do the same, he thought. For good measure they were “set” with oyster spat. It’s been a mixed success, he told me. There’s still too little oxygen, and the oysters failed to get a foothold. “[But] we’ve got live bottom,” he said, always quick to accentuate the positive. The lump, he said, now has worms and two species of mussels all summer.

Our next stop, Aisquith Creek, is a straight-up success story — where a sanctuary oyster reef built on concrete rubble now sports masses of bivalves, some to 6 inches.

And what looks like a pollution slick in the shallows between the reef and the shore turns out to be underwater meadows of native Bay grasses, so thick they calm the choppy waters above them to a smooth sheen. Redhead grass, wigeon grass, pondweed — we counted five species.

“In my 46 years the river’s come a long way back,” John Page said. “The late 1970s and early 1980s were not a happy time. We couldn’t catch fish anywhere below a few feet. The grasses were gone.”

The Severn is all but entirely hemmed in by suburbs, so septic tanks and stormwater runoff make water quality improvements an uphill battle. But in recent decades, he said, better runoff controls and development restrictions, mostly under Maryland’s Critical Area Act of 1984, are boosting a comeback.

“Within a hundred yards I can show you things out here that make you smile and clap your hands, also things that make you cry,” he said. “And that is the story. The Clean Water Blueprint [for restoring the Chesapeake] is working, but we’ve got systemic problems and a long way to go.”

A thunderstorm chased us off the river before we could cast a line. But as the Bay’s master educator once wrote: “Our excuse to the world was that we were fishing, but we were looking [at] tides, temperature, salinity, birds, plankton … plugging ourselves into the system, ready to be grateful for whatever it had to offer us.”