Zebra and Quagga Mussel Monitoring Program

The Center for Lakes and Reservoirs at Portland State University coordinates the Zebra and Quagga Mussel Monitoring Program to help prevent the continued spread of invasive freshwater mussels such as zebra and quagga mussels. Zebra and quagga mussels cause far-reaching damage to water structures and native ecosystems. Monitoring and early detection of these mussels are key to minimizing the risks for western water bodies. There are multiple methods used for early detection monitoring including artificial settlement substrates (e.g. PSU sampler shown below), plankton, natural substrates (e.g. rocks), SCUBA, and ROV. There are many agencies and volunteers involved with these efforts. Prvention and containment efforts are dependent on accurate monitoring, early detection, and efficient information dissemination. The Center for Lakes and Reservoirs at Portland State University maintains the online, interactive Zebra and Quagga Mussel Monitoring Map to increase the efficacy of these early detection efforts by identifying data gaps and increasing regional coordination.


Navigating the Online Mussel Monitoring Map

The Zebra and Quagga Mussel Monitoring Map displays data stored in the Portland State University's online database, and shows who is monitoring what water bodies using what methods, and the status and date of the last reports regarding these efforts. The data are queried in several ways.

Using the Search function

The Search function allows a user to directly query the database by typing the name of a water body (e.g. Columbia River) into the Water Bodies box, and/or typing in a date in the Date Last Checked box (e.g. 2008 or 2008-06-01), as well as selecting frrom the dropdowns provided for Status, Substrate Type, and Provider. After clicking on "search", a table of the results will be diplayed in the bottom of the Search function box and the map will also change to visually display the search results. Spelling and proper use of capitalization is important when typing a water body name.

Using the Info Click function

The Info Click function is another way to search the online database, and is used by clicking on an individual map symbol. After clicking on a map symbol, a pop-up will provide information regarding that specific site such as monitoring station name, and the status of the efforts. It may be necessary ro zoom-in on the map to click on individual monitoring station map symbols.

Zoom-in function

There are several ways to zoon-in on specific areas of the map. Typing a water body name in the Search function will automatically zoom-in on that area. Double-clicking the mouse on a certain region of the map will zoom-in on that area. The user can also zoom-in on the map by moving the bar closer to the "+" in the upper left-hand corner of the map. For faster map naviagation (e.g. zoom-in), select more simplistic base layers and cultural layers in the Layers box.


The base layers of the map can be changed in the Layers box to show locations of existing mussel populations, locations of monitoring based on the results (e.g. non detect), monitoring methods (e.g. plankton), as well as showing different map attributes (e.g. roads and cities). The locations of existing mussel populations are obtained from the US Geological Survey NAS- Nonindigenous Aquatic Species database. These data generally represent established populations. Reports come from federal, state, and municipal agencies, universities, public utilities, and private firms. No responsibility is assumed by the US Geological Survey in the use of these data. The base layers on the Zebra and Quagga Mussel Monitoring Map are automatically updated with changes made to the US Geological Survey database.

Adding Data to the Online Map

The map user can add information regarding early detection monitoring efforts to the database and the online map. Volunteers within the Portland State University Zebra and Quagga Mussel Monitoring Program can enter monitoring data online (e.g. monthly reports). There are early detection efforts that are not directly coordinated by Portland State University, and it is important to include these other efforts to increase regional coordination and beeter identify gaps. Monitoring data can be entered by clicking on the link below. Data entered by the map users are not displayed on the map until it is approved by Portland State University.


Zebra and Quagga Mussels

size range

Size ranges of zebra and quagga mussels

Zebra (Dreissena polymorpha) and quagga mussels (D. bugensis) are native to the Caspian Sea in Asia. They made their way to the Great Lakes Region via ballast water of a transatlantic vessel in the late 1980’s. Within 10 years, these mussels colonized the Great Lakes and the Mississippi, Tennessee, Hudson, and Ohio River Basins. These mussels recently colonized water bodies in western US, including the lower Colorado River and the associated aqueduct systems in southern California and Arizona. Over the next ten years, the US Fish and Wildlife Service estimates a potential economic impact of $5 billion to the US and Canada within the Great Lakes region alone.

Photo of Zebra mussels clogging a pipe

Pipe clogged with Zebra mussels

Zebra and quagga mussels are an extremely invasive species, causing far-reaching damage to water structures and native ecosystems. These freshwater mussels attach to manmade structures, particularly concrete and pipeline, impeding water movement through hydroelectric turbines and intake structures for drinking water and irrigation systems. Zebra and quagga mussels are capable of filtering large quantities of water for feeding purposes. While this may appear beneficial, reduced phytoplankton impacts macroinvertebrates such as native clams. Additionally, increased water clarity may encourage unwanted rooted aquatic vegetation. Zebra and quagga mussels’ fecal material may also contribute to taste and odor problems with drinking water sources.

Stopping the Spread

The 100th Meridian Initiative has been coordinated between state, provincial, and federal agencies to prevent the further spread of zebra and quagga mussels as well as other invasive species. Zebra and quagga mussels are easily spread because of human mediated vectors and hydrologic connections. Juvenile and adult mussels attach to solid substrates with byssal threads, but they can also detach and crawl to new locations on their foot. These mussels are transported to new water bodies by trailered watercraft and other equipment in contact with the water. Zebra and quagga mussels have planktonic larvae that are easily dispersed with water currents and ballast water. In order to stop the spread, the 100th Meridian Initiative has brought together all the stakeholders to pool resources and increase coordination and efficacy of their efforts.

byssal threads

The byssal threads of a quagga mussel

planktonic larvae

The planktonic larvae of guagga mussels


Preventing the spread of zebra and quagga mussels to the Columbia River Basin is the primary objective of the Zebra and Quagga Mussel Monitoring Program coordinated by the Center for Lakes and Reservoirs. The Columbia River is a vital economic, social, and recreational component of the Pacific Northwest.

portland sampler

An artifical settlement substrate used for monitoring, often called a "Portland Sampler"

The Zebra and Quagga Mussel Monitoring Program coordinates volunteers throughout the West who have access to lakes and rivers. Volunteers are provided artificial settlement substrates to hang on their docks and monitor for mussel colonization. Reply cards are submitted by volunteers to the Aquatic Nuisance Species Volunteer Coordinator at the Center for Lakes and Reservoirs to indicate signs of colonization. If there is a positive sighting, authorities are alerted and further steps are taken to determine the extent of colonization.

Early detection monitoring is difficult because newly established populations are inherently rare, these mussels are spatially clumped, and there is a lot of potential habitat. More people looking in more places increases the likelihood of detection. The artificial settlement substrates are effective but limited in surface area. Every solid object in the water is a settlement monitoring device. Turn over rocks . Feel along the undersides of docks. Inspections are both visual and tactile.

attached to a rock

Zebra mussels attached to the sides of a rock


Response card

Monthly response card - Download the volunteer monitoring card (pdf)

Early detection efforts are also focused on the planktonic larvae. Larvae are collected with a plankton net. The Center for Lakes and Reservoirs maintains a laboratory that inspects plankton samples for the presence of these mussel larvae using cross-polarized microscopy.

veliger sampling

Plankton sample being collected by US Army Corps of Engineers staff.

For additional information about becoming a volunteer or the online map please contact Steve Wells, Zebra Mussel Volunteer Monitoring Coordinator.

Conact Information

Steve Wells

Portland State University
Center for Lakes and Reservoirs
PO BOX 751
Portland, OR 97207-0751
Ph: 503-725-9075
Fax: 503-725-3834




For additional information on zebra and quagga mussels:


100th Meridian Initiative

USGS Nonindigenous Aquatic Species