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Aquatic Plants for Water Quality Maintenance in Water Features and Fountains by Mary Willeford-Bair, Catherine Dewey, and Walter Zachritz

The National Park service is responsible for the management of a variety of constructed water features across the Service. Constructed water features are the built features and elements that use water for aesthetic or utilitarian functions in a landscape. Examples of features associated with constructed water features include fountains and ornamental pools, canals, cascades, pools, and reservoirs. These features vary by water source used, climate, location, discharge requirements, discharge location, water treatment options and practices, plant or animal communities, general operation, flow schemes, and a host of other attributes. The materials used for these features range from masonry and tile to various metals such as bronze, stainless steel, or iron, and are often combinations of these. Some features consist of concrete basins, synthetic-lined pools, tiles, or unlined ponds. Many of these features are strictly visual or provide auditory aesthetics and function with little or no biological activity. Other features support artificial but complex ecosystems that are functional components of the landscape. This special category of water feature that relies on aquatic plant growth coupled with microbial processes to maintain water quality is the focus of this presentation. The effects of water quality on the materials of the water feature will be examined.

Aquatic plants with their diverse speciation, prolific growth rates and hardiness in many climate zones are excellent for application in many areas of water quality improvement. They can be integral to the water feature form or they can be separate treatment units through which water is circulated. Aquatic plants can be floating, submerged, or emergent. The plants and associated roots provide a media for the growth of a wide range of beneficial bacterial and other micoorganisms that, along with the plant growth and uptake, contribute to the treatment process. Care must be taken when selecting aquatic plants as there are many species that can become a nuisance when introduced into the local environment. The spread of water hyacinth beginning in the early part of the last century from Africa to South America to North America is a good example of the spread of an invasive species that has become a major nuisance. Native species can provide many of the same attributes that exotics species have without the risk of an unwanted introduction.