This waterfall garden, with stream beds at three different angles, was built for Stephen and Sharon Cuchel of Long Island by landscape designer Eric Hagenbruch. The Cuchels’ waterfall cost about $85,000 to install.

TPN / KEN SPENCER

MELVILLE, N.Y. Two deep-pocketed clients, two landscape designers, the same idea: design a backyard with a waterfall where no waterfall existed, and try to make it look natural.

It’s as if a really big giant scooped up a chunk of wilderness, hopped on a passing magic carpet and plunked his cargo onto Ed Drohan’s backyard.

A fanciful scenario perhaps. But Drohan, a water garden designer in Sag Harbor, says his replica of a mountain waterway is a dead ringer for the primal forest he rambled in as a boy.

“I grew up in the woods; my family’s home backed up on 100 virgin acres of forest and lakes and hills,” says Drohan, 41. “My friends and I were always exploring and camping in all those hidden little gems in the woods that made us feel like we were the only humans to ever set foot in there.”

His vivid boyhood memories of nature in the raw now serve him well. He is certified by Aquascape, a nationwide supplier of landscaping materials that also runs seminars on the latest design techniques. And he is a division manager for Ray Smith and Associates, a New York landscaping company.

When a career move brought Drohan and his wife, Sara, 32, an elementary school teacher, to Long Island three years ago, their search for a house, he says, “ruled out any that didn’t have grade-level changes, because an existing slope was the first requirement for the natural landscape I intended to develop for my own home.”

Brooklyn-bred Sara’s chosen domain, adds her husband, was their cozy wood-shingle-clad house (today, they share it with their 1-year-old son, Adam). But Drohan eyed their hilly backyard with anticipation of creating his dream waterscape on the boulder-studded slope.

In just one week, he and his crew muscled 80 tons of craggy Pennsylvania moss rock onto the barren, one-third-acre site, turning Drohan’s nostalgic design into reality while using techniques to keep from disturbing the native moss and lichen. What Drohan describes as “a hundred-foot-long river” now flows down the slope, pausing in a small, tranquil pond and then, in a nature-mimicking zigzag, gushing over a series of rocky waterfall ledges and finally spilling into a large fish pond stocked with koi.

The water is pumped via an underground pipe up to the head of the “river” and recirculated. Nature, too, had a hand in authenticating the untouched wilderness effect: During the site preparation, the antler of a deer was unearthed and remains near where it was found, and, when one of the trees that rim the slope fell, it was left exactly where it landed, as it would in the forest.

“I planted some water hyacinths in the ponds, but only the native grasses along with some yarrow and morning glories that came up by themselves are growing there — nothing that doesn’t belong,” Drohan says.

“It’s important to aerate the water by letting it bounce and splash over the rocks, and I leave it running year-round to keep it from stagnating,” Drohan explains. “Besides, the water garden is as beautiful in the winter as it is in the summer.”

Meanwhile, on another part of Long Island, a longtime client wanted a waterfall, and the undeveloped area he’d chosen on his otherwise parklike three-acre estate was ideal. Halfway up a rugged slope, a windblown wild cherry tree had long ago taken root, leaning almost sideways. At the foot of the slope, a shallow gully separated a hilly rise, where the designer had built a gazebo a few years before.

Owner Stephen Cuchel, a dentist, and designer Eric Hagenbruch walked the site together, each envisioning the perceived outcome in perfect agreement.

Except for the cherry tree.

“Steve wanted me to chop it down,” says Hagenbruch. “He said it looked like it was about to fall over.”

But the designer’s vision soon sparked his client’s imagination — the pretty tree would arch gracefully over the gushing waterfall.

And so the tree was saved.

Rather than bringing in heavy equipment that would compact the ground and damage roots of nearby trees and shrubs, Hagenbruch, owner of Finesse Landscape Design, set his crew to hand carve the excavations for his elaborate concept: a cluster of three falls and two ponds stocked with koi, all fed by a meandering stream. Hand-picked boulders and rocks bought on Long Island were placed strategically in a carefully planned jumble along the banks, some overflowing onto the grassy hillside as if, in eons past, a shifting glacier had tossed them there.

“I angled each fall in a slightly different direction so that there’s a view of water from every vantage point,” says Hagenbruch, who completed the installation two years ago.

Well-hidden but powerful pumps force torrents of water along the stream beds, over the falls and into the ponds, then recirculate it.

Simple plants that emulate the spontaneity of natural growth were tucked into rocky crevasses under the filtered sunlight: dainty creeping Jenny trails over the rocks reaching chartreuse tendrils into the ponds, where aquatics such as Sweet Flag iris, water hyacinths and acorus thrive, creating ecosystems of their own.

Cuchel and his wife, Sharon, both in their 70s, are fixtures in the area, having lived in a succession of homes for almost 40 years. He is a village trustee and she is a retired teacher; they have five married children and 11 grandchildren, ages 1 year to 18 years.

A generous patriarch, Cuchel often hosts the whole clan on jaunts to places such as India or to Switzerland for ski vacations. At home in Roslyn Harbor, the family frequently convenes in the centerpiece of the estate, a spacious mansion the Cuchels have owned for about 12 years; it was built in 1916 for a partner of Thomas Edison.

Hagenbruch keeps the grounds spick-and-span year-round, paying special attention to greenery at the front entry. “Sharon likes to have the season’s theme always up to date,” he says. From spring bulbs to summer’s fuchsia to autumn’s ornamental kale and heather and at Christmastime, holly and evergreens, the entry is always welcoming.

“Because the entry is shaded by an overhang, we put the plantings in large urns on wheels and bring them out to lap up the sun as often as possible,” says Hagenbruch. “And we set up a drip watering system in them so they never dry out.”

“We wanted the waterfalls there because it had been an unused spot on the property and the hilly terrain made it a logical location,” Cuchel says.

“And now our 4- and 5-year-old grandchildren love to play there, poking their toes in the water, feeding the fish and just enjoying the place while someone always keeps an eye on them from the gazebo. We leave binoculars there to watch the birds and ducks that come around. It’s like the falls have always been there.”

Tips for waterfall design

Professional landscape designers Eric Hagenbruch and Ed Drohan offer some tips for waterfall design:

•Think location, location, location. Near the house is best for maximum aesthetic effects, and also for the electrical connection to the pump. Equally important is a site on an existing slope, if possible, for the most natural look.

•If there’s no pond on the property, you’ll need to build one. Basic waterfall materials include a rubber liner, a pool pump that connects to an outlet with a safety device called a Ground Fault Interrupter installed by a licensed electrician and, of course, an assortment of boulders and rocks. To save your back, enlist some muscle, ideally muscle with mechanical backup; boulders weigh hundreds of pounds.

•If there’s a slope alongside your pond, you’re in luck. If not, you’ll have to build one. Either way, shape the slope-face into ledges in an irregular pattern, then cover the slope with the liner. Starting at the rim of the pond, stack rocks and boulders topped with flat slabs onto the ledges; test and adjust for water runoff using a garden hose. Hide the pump hose and any exposed patches of liner with smaller rocks. Add shrubs and plants for finishing touches.