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Algae Bloom Advisories
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The 2013 Algae Bloom Season

With a change of season and as cool, wet weather prevails, blue green algae blooms should not be as abundant as they were in summer. As we wait to see the last advisories lifted, program staff advise people to be sure to always stay alert when recreating in your favorite swimming or fishing hole. These ancient forms of bacteria are always present in the water and are generally not noticeable. However, when weather, sunlight and nutrients (nitrogen and phosphorous) are optimal, they multiply and can grow into what is called a "bloom," that often times takes on the appearance of algae. Because many of the blooms are blue-green in color and many times look like algae, the name "blue-green algae" has been used to describe them. Although some blue-green algae have the potential to produce toxins under the right conditions, toxins are not always produced, and when produced, are not always at levels that are harmful. 

Exposure to harmful algae blooms decreases in cooler months, due in part to the change in our recreational activities. During the fall/winter season we often go fishing, hiking, hunting and walking with our dogs at lakes, reservoirs and rivers around the state. If you participate in these activities, especially with your pet, we recommend you continue to be vigilant about potential exposure to waters that look suspicious - foamy, scummy, thick like paint, pea-green, blue-green or brownish red. Remember, even if an advisory is not in place or you didn't notice a sign, you are always your own best advocate when it comes to looking out for you, your family and your pets.

This summer we had nearly the same number of advisories as in 2012, when we had nine. We continue to have a reduced number of advisories over historical numbers because of a decision by some waterbody managers to perform toxin testing when a bloom is first identified, and throughout the bloom lifecycle. This testing provides 'actual' toxin and exposure data rather than 'potential' for exposure to toxins that may or may not be present at harmful levels. When initial toxin data show that health advisory guidelines for recreational waters are not exceeded and therefore not harmful to human health, no advisory is issued. This allows the public to enjoy a lake or reservoir even though a bloom is present. When initial toxin testing is not performed, advisories are issued if lab analysis identifies blue-green algae cells with the potential to produce toxins, and at cell counts above recreational guideline values. The map and table below are continually updated with the most current information on advisories issued and lifted throughout the season for waterbodies that are monitored. Be advised however, that only a fraction of all waterbodies in Oregon are monitored due to limited physical and monetary resources.

Whenever you are enjoying the many lakes, reservoirs, ponds and rivers across Oregon always remember, when in doubt, stay out!


 2013 Advisory Listing
​# Waterbody​ Region​ County​ Dominant Species/Toxin​ Cell Count/Level​ ​Start Date ​End Date ​Duration (days)
1​ Willow Creek Reservoir​ Northeast​ ​Morrow ​Anabaena flos-aquae ​3,551,625 6/18/2013 8/13/2013​ 56​
2​ ​Lost Creek Lake Southwest​ ​Jackson Anabaena flos-aquae​ 1,175,333 6/20/2013 7/05/2013​ 15​
3​ ​Dexter Reservoir ​Willamette ​Lane ​Anabaena flos-aquae ​2,228,000 7/03/2013 9/19/2013 78​
4​ ​Dorena Reservoir ​Willamette ​Lane Anabaena flos-aquae​ ​556,000 7/25/2013​ 9/24/2013​ 61​
5​ ​Devils Lake ​Northwest ​Lincoln Microcystis​ Unknown​ 8/01/2013​ 11/21/2013​ 112​
​6 ​Blue Lake Willamette​ ​Multnomah ​Visible Scum ​Unknown 8/06/2013 8/09/2013​ 3​
​7 ​Fern Ridge Reservoir Willamette​ ​Lane ​Visible Scum ​Unknown ​8/15/2013 12/18/2013​ 125​
​8 ​Blue Lake ​Willamette ​Multnomah ​Visible Scum ​Unknown 9/09/2013​ 9/13/2013 ​4
9​ ​Lost Creek Lake ​Southwest ​Jackson Anabaena flos-aquae​ 1,032,975​ 9/13/2013 12/30/2013​ 109​
​10 Walterville Pond​ ​Willamette ​Lane ​Microcystis ​46,000 9/13/2013 10/3/2013 20​
11​ Tenmile Lakes​ Southwest​ Coos​ Microcystis​ Unknown-high toxins​ 10/04/2013​ 12/03/13​ ​60
​12 ​Willow Creek Reservoir ​Northeast ​Morrow ​Anabaena flos-aquae 1,104,950​ 10/25/2013​ 1/21/2014​ 88​

Important note about the South Umpqua River in Douglas County - There is a permanent advisory in place for this portion of the river. Signs are posted along the shoreline at most popular river access routes. Be aware of stagnant pools of water that can develop in the bedrock along the riverbank. These pools are known to develop blue-green algae blooms that can be very harmful to pets and children if exposed. 

Details of historical health advisories issued in previous years can be found in the Advisory Archive.

Subscribe for email notification Join our Listserv

The HABS program has created a listserv to share information with partners, stakeholders and interested people. When an advisory is issued, an email is sent to subscribers that includes the news release and water sample results (algae species and cell counts). Emails are also sent when an advisory is lifted. Other timely information may be periodically shared as well. Join the list.​​​