Publication Summary

This booklet is published by the Department of Ecology to increase public awareness of invasive, exotic aquatic plants. None of the plants illustrated here are native to the Pacific Northwest. Many of the plants come from exotic locations such as Asia, Australia, Africa, and South America. Most have already invaded Washington and are well established in certain lakes and rivers.

This booklet is published by the Department of Ecology to increase public awareness of invasive, exotic aquatic plants. None of the plants illustrated here are native to the Pacific Northwest. Many of the plants come from exotic locations such as Asia, Australia, Africa, and South America. Most have already invaded Washington and are well established in certain lakes and rivers.

These plants are all truly invasive and carry with them, few, if any, of the natural controls that keep them in check in their native ranges. As a result, their uninhibited growth carries the potential for great harm to wildlife habitat as well as to the recreational uses of lakes and rivers. Once established, the cost for management of these plants is very high.

These plants form single species stands that exclude beneficial native aquatic species. They form surface mats that create areas of stagnant water suitable for mosquito breeding. They create areas of low oxygen and high pH. They form swimming and boating hazards. In short---these are highly undesirable plants.

Many of these plants have been introduced into Washington waters through well-meaning aquarium owners who have dumped their aquarium fish and plants into a lake or stream. Eurasian watermilfoil, fanwort, and Brazilian elodea are all thought to have been introduced to Washington by people dumping aquariums. Once introduced, these plants can be readily spread by boaters carrying plant fragments into uninfested waters.

The early location and identification of new colonies is important. If you think that you have found one of these species, please contact Kathy Hamel (360) 407-6562 (e-mail kham461@ecy.wa.gov) or Jenifer Parsons (e-mail jenp@ecy.wa.gov) at the Department of Ecology for advice. You may also send a plant to Ecology for confirmation. Contact Kathy or Jenifer for directions on mailing plants.

Once an exotic weed becomes wide spread in a lake or river, management is often ongoing and expensive. Alert lake residents can discover pioneering colonies of an exotic species before it becomes established. In these cases it is sometimes possible to remove the plants before they become widespread. Lake residents need to be aware of how to identify exotic aquatic plants. The information and illustrations in this booklet will help with the identification of exotic species.