A steep bank rising behind the Sunset Northwest Idea House in Portland seemed like the perfect place for a waterfall. Better yet, why not two cascades so they could be seen from all rooms facing the garden? That was the thinking of Gerald Ouellette of G&O Landscaping in Sherwood, Oregon (503/625-6625), who specializes in building natural-looking waterfalls.

Using an excavator for rough work and shovels to finish, Ouellette sculpted the bank into a series of ledges. Starting from the bottom up, he laid a .45-mil rubber liner over the watercourse, then carefully placed boulders from the Columbia River Gorge on the liner. At the top of the watercourse, two streams converge from different directions, tumbling over flat ledges before pouring together into a pool next to the patio.

Two pumps hidden under rocks in the pool recirculate 150 gallons of water per minute from the pool to the falls. A biological filter beneath the stones keeps the water running clear.

Up on the hill, pinkish white blossoms of Abelia chinensis and purple-flowered verbena soften rock faces near a bright green tuft of 'Greek Spicy Globe' basil. The blue flowers of catmint and the silvery foliage of licorice plant (Helichrysum petiolare) spill out of nooks and crannies. Around the pool, a nicotiana bears starry white blooms, while hostas ('Krossa Regal' and 'Invincible') put out pale lavender flowers. In the crevices among the rocks, patches of brilliant green Irish moss (Sagina subulata) catch water droplets that sparkle in the sun.