Invasive Species

Minimizing the spread of invasive species through field work

Washington law (RCW 77.15.290) prohibits the transportation of fish, wildlife, or aquatic plants from one location to another. (RCW 77.08.010) defines "wildlife" as all species of the animal kingdom whose members exist in Washington in a wild state.) The Washington Administrative Code also prohibits transporting certain terrestrial plants (WAC Chapter 16-752).  This webpage provides information to help people who work in the field obey the law. Following the procedures described here will also reduce the risk of spreading things like fish disease-causing bacteria. These procedures will not eliminate all risk of spreading invasive species; they are an attempt to balance risk and cost.

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We have divided Washington into areas of "moderate" concern and areas of "extreme" concern. Areas of Extreme Concern have, or may have, invasive species like New Zealand mud snails that are particularly hard to clean off of equipment and are especially disruptive to native ecological communities.

Areas of extreme concern include the Snake River; Columbia River below the Hanford Reach area; Burnt Bridge Creek and Vancouver Lake; watersheds of the lower tributaries to the Columbia; Surfside canals; Capitol Lake; the Chehalis River below Blue Slough; Union Slough at the mouth of the Snohomish River; a tributary to the Naselle River; and the following creeks that flow into Lake Washington: Thornton Creek, McAleer Creek, May Creek, and Kelsey Creek (including tributaries to these creeks). These areas are shown on the maps below.

We have developed a common standard operating procedure (SOP) for the two types of areas.  For areas of Moderate Concern the SOP focuses on visual inspection and physical removal (with the exception of felt-soled waders). For areas of Extreme Concern, the SOP requires decontamination under certain circumstances, primarily because the invasive species found in these areas are small and difficult to remove through visual inspection alone. 

Felt-soled Waders

Felt-soled waders have been singled out in the SOP for special treatment (decontamination), even in Moderate Concern areas, because studies have shown that organisms like Didymo (link to Wikipedia) can get worked into the felt. The felt also retains moisture, keeping the organisms viable for a relatively long time. Felt soles are increasingly coming under fire. In 2008, Trout Unlimited argued that they should be not be used at all. Several states, including Alaska, have banned them altogether (USA Today). Yet many people feel that felt soles are essential for safely navigating algae-covered rocks.

There are alternatives to a permanently fixed felt sole that may simplify decontamination. One solution is to use removable felts. Removable felts can be swapped out between work areas to allow for sufficient time for decontamination, and a batch of felts can be decontaminated after returning from the field. However, some people feel that removable felts are prone to slipping on the boot.

There are also some new products on the market designed to replace felt soles. Some folks like these even better than felt—others aren't convinced.

Hot Water

Something more than inspection and rinsing is necessary when cleaning/decontaminating:

There are various decontamination options available, but hot water has several advantages: its effectiveness is clear against most organisms, it is non-toxic, and there is no waste. However, the water should be 140ºF, which is hotter than most tap water systems. Water at 120ºF may be used if 140ºF water is not available but a longer contact time is required. Portable propane-fired on-demand hot water systems may be useful in some applications.

Marine Systems

All procedures for minimizing the spread of invasive species apply to marine as well as freshwater systems. Currently, there are no "Extreme Concern" marine areas.

Please use particular caution when contacting substrate in tunicate areas. For example, be sure your anchor is well-rinsed. More information about tunicates, including location maps, can be found at the Invasive Tunicates website at WDFW.

Supporting Documents

Contacts for specimen identification

If you come across what might be an invasive species, try to get a few good pictures and location information (GPS point or descriptive).  Collect a sample if it can be done safely and without spreading the organism.

Other Invasive Species Information:

General Information

Information about Decontamination

Information about invasive species and distribution


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