Water quality investigation at Hagg lake

For Immediate Release: Friday, July 16, 2021

UPDATED: 07/20/2021
Sponsored by: Support Services Department, Facilities and Parks Services Division

Hagg Lake Water Quality Update

Today, July 20, 2021, Washington County Facilities and Parks Services learned that cyanotoxins associated with seasonal Cyanobacteria (harmful algae) blooms were not detected in water samples taken on Thursday, July 15, from five separate locations around Hagg Lake. As recommended by the Oregon Health Authority (OHA), the samples were tested for four different cyanotoxins that could pose a health risk to people and pets recreating in bodies of water. Locations included Bobcat Cove, C-Ramp Recreation Area, Dam Overlook, Eagle Point Recreation Area and Sain Creek Recreation Area. All tests were negative for Anatoxin-a, Cylindrospermopsin, Microcystins and Saxitoxin.


Although these findings are very encouraging, Washington County continues to urge visitors to Scoggins Valley Park to use caution when recreating in Henry Hagg Lake—or any body of water—and be very familiar with Cyanobacteria blooms and related health concerns, especially when accompanied by children and pets.

Following a report of the tragic death of a family pet shortly after swimming in Hagg Lake earlier this week, the Oregon Health Authority’s Cyanobacteria (Harmful Algae) Bloom Surveillance (CHABS) Program is investigating the incident. At this time, additional laboratory testing is currently underway to check for the presence of related cyanotoxins in samples taken from several sites around the lake. The public will be notified as soon as results are available but even if negative, visitors should use caution when recreating at Hagg Lake—or any body of water—and become familiar with Cyanobacteria blooms and related health concerns.


Although commonly referred to as algae, Cyanobacteria are actually primitive bacteria found naturally in fresh and salt water all over the world. They are generally beneficial to the environment and help to sustain oxygen levels in the atmosphere. In warm weather, nutrients and low water flow can allow these bacteria to multiply quickly into what is known as a “bloom.” Sometimes these blooms can produce cyanotoxins that can be harmful to people and pets.

Exposure occurs when people swallow water with cyanotoxins during recreational activity, or when using affected water for drinking or cooking. Cyanotoxins are not absorbed through the skin, however, a red, raised rash or irritation of the skin and eyes can develop after contact with a bloom. If enough water is swallowed, a person may experience one or more symptoms that mimic food poisoning: stomach cramps, diarrhea, nausea and vomiting, or more serious symptoms: numbness, dizziness, and shortness of breath. Symptoms generally begin within 24 hours and last 72 hours. Children and pets are at increased risk of exposure because of their size and level of activity. 


A health advisory is issued when sampling data determines that cyanotoxin levels are above recreational use values (RUVs) established by Oregon Health Authority. OHA has established RUVs for people and dogs, but advisories are only issued when levels are over the values for people. Even if an advisory is not in place on a water body, a bloom and toxins can still be present, and in most cases harmful to pets. Dogs are extremely susceptible at very low levels and exposure could result in death. Dogs will exhibit reactions after the first hour of exposure and those with symptoms such as diarrhea, vomiting, breathing problems, difficulty walking or standing or loss of appetite should be taken to a veterinarian as soon as possible.

Those who believe they or their pets have become ill after swimming in Henry Hagg Lake or any water body in Oregon are encouraged to email the CHABS Program at HAB.Health@state.or.us.


Since most waterbodies in Oregon are not monitored, OHA staff recommend that people become familiar with their surroundings and know the signs of a bloom before entering the water. Don't go into water that looks foamy, scummy, thick like paint, pea-green, blue-green or brownish red. A good rule of thumb for everyone, including pets, is: When in Doubt, Stay Out! Please visit the Oregon Health Authority webpage for additional information about Cyanobacteria and related health concerns.


Drinking water served to customers in Hillsboro remains safe to drink and use. There is no need to ration bottled water or boil water before use. For more information, please visit www.hillsboro-oregon.gov/Home/Components/News/News/12902/44.

Media Contact:

Julie McCloud, Public Affairs & Communications Coordinator