John Hoke has friends all over downtown. They're wild. Some have shells, some wear feathers, some have gills. They cause him grief, time to time, but he loves them, anyway.

"There's one of my boys," Hoke said last week. "See the turtle with the hole in its back? We rescued him from the C&O Canal in 1968. Somebody shot him. I took the bullet out, patched the shell with silicone and put him in this pond."

Eighteen years later, the wounded turtle sunned on a log at Simon Bolivar Park at 19th and C streets NW, in front of Interior Department headquarters, oblivious to the hubbub of trucks, buses and cars screeching by.

Bolivar pond used to be just another lifeless, antiseptic Washington architectural pond until Hoke came along and filled it with logs and marsh grass and muck from Kenilworth Gardens on the Anacostia River. Now, it's a lively urban wildlife refuge. Ducks live there, and largemouth bass, even a wounded turtle.

Hoke, a cigar-smoking, bureaucratic bear of a man, is the madcap National Park Service scientist who believes Washington's aquatic monuments need life.

Knowing, as he does, that dirt and disorderliness are the stuff of life, he brought in truckloads of mud, boxes of aquatic plants and various fishes to enliven the Reflecting Pool, Constitution Gardens, Bolivar Pond and a tiny pond in front of the National Park Service's regional headquarters on Hains Point.

His system works; sometimes too well.

Last April, a wild mallard hatched a string of ducklings on the island in Hoke's vest-pocket refuge at Hains Point. The ducklings immediately began paddling around the 10-foot-by-40-foot rectangular pond.

Park service employes who drifted out for a brown-bag lunch on the concrete apron were delighted at this glimpse of nature, Hoke said, until a largemouth bass, another resident, lunged out of the black water and gobbled up one of the fuzzy newborns.

"The bass ate three or four ducklings before I got there," said Hoke, "and I guess it was too much nature for some people. They kept coming up to me in the halls and saying, 'You and your unprintable bass.' "

Jack Fish, director of the park service's National Capital Region, made Hoke drain the pond and remove the bass before he refilled it, and this year the mallard is back. "She's in there now," said Hoke, proud as a parent, and sure enough, barely visible in a tangle of reeds, the hen was roosting away the other day.

Hoke's scheme has been to save Washington's shallow, concrete-bottom architectural ponds from being overgrown with algae, as they were for years, by putting more desirable life forms in the water to eat up nutrients.

Over the last decade and a half, he's put boxes of submerged aquatic plants and poured truckloads of Kenilworth muck in various ponds, which eased algae problems and attracted booming populations of wild waterfowl to the city, particularly to the six-acre Constitution Gardens pond on the Mall, where they feast on hydrilla and wild celery and handouts from passersby.

"One day, I was standing next to a tourist, watching a homeless person feed the ducks there," said Hoke. "The tourist said, 'Isn't that wonderful, a person who doesn't have enough to eat himself, still finding something for the ducks?'

"Well, I noticed he was leading some of the ducks right out of the water with his trail of food. Just about then, a duck got too close and he reached down and snatched it, wrung its neck and took off running.

"The tourist said, 'What are you going to do about it?' Well, what could I do? It's not illegal to hunt in Washington," said Hoke. "It's only illegal to use a gun."

There also are enough bass and bluegills in the Constitution Gardens pond these days that sport fishermen sometimes slip down at dawn, before tourists arrive, and nail a few.

Rick Robbins, a park service lawyer, said two years ago he was catching largemouth bass up to four and five pounds flyfishing at Constitution Gardens, but last year most of the fish were in the seven- to eight-inch range.

The park service has no rule against fishing the lake, Robbins said, but discourages it during the day when tourists are around, for fear someone will get hooked accidentally.

So there it is -- bass, bluegills, turtles, ducks, Canada geese, hydrilla, wild celery, zooplankton, phytoplankton, hunting, fishing, predatory attacks -- the whole, beautiful, grisly natural tableau right here in the heart of the big city. And nowhere else, as far as anyone knows.

"I'm not aware of any other cities that manage their little waters as refuges this way," said Robbins. "Most cities look on ponds like this as decorations, like the pool at Union Station, with waterspouts and a place to wade.

"The park service turned Hoke loose, told him to come up with something more natural and less expensive to maintain," said Robbins, "and what resulted is just plain lovely."