The Organic Gardeners: Invasives From Water Gardens Escaping Into Waterways

  • Purple loosestrife is an invasive you should never plant in the garden. Photo: Liz West

Water features have become popular parts of home gardens in recent years. The sound of bubbling water and the sight of visiting animals of all types make them great additions to backyards, but there may be a hidden cost to installing a water feature: the potential of introducing damaging invasive species to local waterways.

There are a few ways in which a non-native species can escape a water feature and make their way into ponds and local streams, but according to Jessica Walliser, the most common is naturally occurring flooding.

“Number one is if you live in an area that’s prone to flooding, sometimes water features will get flooded. They’ll overflow and then those plant species can kind of go out, and if you live near a stream or a pond, then they’ll escape into the waterways,” she says.

Once a non-native species has found its way into the environment, it has the potential to seriously harm the native inhabitants. Plants and animals that have never been exposed to the invasive species may find themselves struggling to compete for resources, and may even end up being displaced completely.

“Things like water lettuce, yellow flag iris, yellow floating hearts, and even animals like zebra mussels and Chinese mystery snails, they’ve all kind of escaped cultivation and they’re really causing a lot of problems, so we have to really watch them,” says Walliser.

As beautiful or exotic as they may be, species like yellow flag iris or the Chinese mystery snail may not be the best options. Instead, there are many native alternatives that can be great additions to a water feature. The American lotus, pickerel weed, arrowhead, and water lilies are all native to western Pennsylvania, and there is always the option of finding an aquatic nursery to find even more replacements for invasives.

Walliser says if you do decide to replace an invasive plant with a native alternative, make sure that they’re disposed of properly.

“You really need to make sure you dispose of those plants properly, which is burning them or disposing of them in the garbage," she says. "You don’t want to go ahead and throw them into a local waterway because it really could cause problems.”