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Swimming With the Irises
Aquatic Plants Breathe Life Into Backyard Pools

By Adrian Higgins
Washington Post Staff Writer
Thursday, July 20, 2006; H01

Swimming pools are as popular as ever, more so perhaps as back yards are converted into outdoor entertainment areas. Nothing wrong with that in this week of sapping heat, but for landscape designers like Tom Mannion, incorporating a pool into a garden can be tricky.

The basic rectangular pool, clear and chlorinated to death, is boring and sterile. "Water is life," said Mannion, based in Arlington, "and yet a swimming pool is not."

Landscape architects and designers are striving to make the pool a less jarring element. One popular approach is to tie it visually, if not physically, to a nearby body of water, artificial or natural.

In Europe, that barrier has been broken altogether. Swimming pools form parts of larger ponds where plantings filter the water. "I guess in theory you could have enough plant life to clean the water," said Richard Arentz, a landscape architect based in Washington. "Can you get it so clean it would meet American tastes? I don't think we are there yet, but it's promising that the Europeans are doing it."

Mannion, however, has put his toe in the water with a couple of his projects in Northern Virginia. In the first, installed in McLean three years ago, he designed a swimming pool with a submerged landing to hold three large pots. The pots are not sealed, and the roots of the plants -- miscanthus grass, canna and dwarf papyrus -- are soaked by the pool water. The chlorination doesn't seem to harm them, Mannion said. He points out that municipal tap water used to irrigate the garden also is chlorinated.

In a second project in McLean, finished last year, he designed a swimming pool with two sunken planters, each loaded with dirt, planted with water iris and mulched with gravel, which helps to hold down the soil. Look closely and you can see the gravel developing algae, but the pond is unclouded by mud and free of visible bugs, and the irises seem to be content. The effect is given a major boost with the installation of a decorative pond on the other side of a flagstone path. The pond is murkier, and enlivened by fish, iris planters mirroring those in the pool, and other aquatic plants growing out of pots. In the fishpond's center, a bubbling fountain in a decorative pot of gravel is actually a biological filter. The swimming pool has its own elaborate filtration system that includes the use of ozone injectors to reduce chlorine use.

In a moist, slow-draining swale bed flanking the fishpond, Mannion has installed bog plants. As the perennials and shrubs develop in the next couple of years, he sees a seamless progression of robust aquatic vegetation from pool to pond to plant bed. He wants the owners, Dick and Viki Clark, to think of the path as a bridge and to believe that the two bodies of water are linked, the fish simply preferring to stay on one side.

Something so modest, however, has left pond maintenance companies scratching their heads. One refused to even consider taking on the contract, saying the firm had one account where the in-pool cleaning robot got dislodged and started squirting chlorinated water into an adjoining fishpond, killing the koi. Others said they couldn't guarantee that the pool would remain "pristine."

"I assume they thought the soil would be like smoke moving through a room if it got into the water, which it just does not do," Mannion said.

Mannion told the pond construction company that any winter cover would need cutouts for the irises. The Clarks opted instead to place a leaf net over the ponds in the fall and to spend extra time in the spring removing windblown debris. Viki Clark, who is known as Jan, said she "can't wait" for the plants to fill out and Mannion's vision to become a reality.

Mannion is a disciple of Dutch designer Henk Weijers and went to see Weijers's naturalistic swimming pool projects in Europe in 1995.

"It's taken me 11 years to work up the courage to do this," Mannion said. "This is an extremely overdue gesture toward the beauty of Henk Weijers's projects." Mannion conceded, however, that filtering pool water through an adjoining artificial wetland would be much more difficult here because mosquitoes are a bigger problem in the United States than in Western Europe.

While other designers have not yet followed Mannion's use of plants in swimming pools, they are striving to integrate the swimming pool more successfully into a larger landscape. "People are much more design savvy and don't want the pool as this big barren thing in the middle of the back yard," said Joan Honeyman, of Jordan Honeyman Landscape Architecture in Washington.

Arentz, whose company is known for its pool designs, has found other ways to convey nature in swimming pools. At a project in Northern Virginia, he created a double-tiered pool lined in boulders unearthed at the site. In the lower pool, a waterfall crashes near a grotto. In another project, in Potomac, he used a lot of natural stone in the decking around the pond and placed a large boulder as a diving platform.

In other projects, he has brought a stark contemporary feel to swimming pools and has used sculpture to suggest a reflecting pool.

Elsewhere, he has integrated a gazebo or a low stone wall that functions as a garden seat wall. But as for plants in the water? "I think Europeans tend to be more relaxed about the idea of swimming. Here, we want it to be clean, to make sure the last bit of algae is filtered out of it."

At a large contemporary house in Tidewater Virginia, landscape architect Warren Byrd created a swimming pool and nearby lap pool next to a designed freshwater pond where native bog and aquatic plants are used to filter storm water from the house. While the pools are not physically linked to the pond, they do form an emotional connection to the artificial wetland and, beyond, to Lynnhaven Bay, a saltwater estuary of the Chesapeake Bay. Water from the freshwater pond is recirculated through a lily pond on the terrace.

"They are basically three related, designed bodies of water that tie together, that relate to the larger body of water in the distance," said Byrd, of Nelson Byrd Woltz Landscape Architects in Charlottesville.

His firm is active in environmental projects, and he would like the chance to work on a European-style, naturally filtered swimming pool. Part of the resistance to it, he said, is the fear that snakes would join the pool party.

Mannion said one of the benefits of growing plants in water, even if they are tropicals in pots, is that you don't have to water them constantly, and yet they attain great size.

And he has noticed that the irises in the swimming pool at the Clarks' house are actually growing larger than those in the fishpond, because the water is heated.

"We have had quite a few people over," said Dick Clark, "and very few have even commented" on sharing a swimming pool with bog plants. "They haven't noticed, or they find it perfectly natural to have plants growing in a swimming pool," he said. Either way, "I'm glad to be on the frontier."

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