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Bull Run Filtration Fact Sheet: Protecting Against Harmful Algal Blooms

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The Bull Run Treatment Projects will enhance our water system’s resilience, reduce future risks, and better protect customers.  The projects include building a new filtration facility that will remove disease-causing microorganisms and other potential contaminants from our water supply. 

Cyanobacteria, also known as blue-green algae, are naturally occurring bacteria that are found around the world in rivers, lakes, and oceans. Some cyanobacteria can produce toxins that can be harmful to human and animal health. Under certain environmental conditions, toxin- producing cyanobacteria can grow out of control and release toxins into the water. This is called a harmful algal bloom. Harmful algal blooms are more likely to form in warm and stagnant water that has high levels of nutrients. High levels of nutrients typically enter water bodies from human-caused sources, such as agriculture (fertilizer and livestock manure), sewage, or stormwater runoff.

Current Conditions in the Bull Run Watershed

  • The rivers and reservoirs in the Bull Run Watershed are not currently vulnerable to conditions that would encourage or support a harmful algal bloom.
  • The land in the Bull Run Watershed is naturally low in nutrients. Additionally, strict watershed protections do not allow activities, such as agriculture or commercial or residential development, in the watershed that would contribute additional nutrients. As a result, the Bull Run Watershed does not have a history of harmful algal blooms.
  • We test Bull Run water for algae on a weekly basis.
  • There are many types of algae found in the Bull Run reservoirs and at the raw water intake. Levels of algae increase on a seasonal basis.
  • The algae found are typical for lakes in the region and do not pose a health risk.

Current Regulations and Cyanotoxin Monitoring

  • There are currently no rules at the federal level for harmful algal blooms or cyanotoxins in drinking water. However, the Environmental Protection Agency may develop rules in the future.
  • Oregon requires some water providers that they determined are at higher risk of cyanotoxins to routinely test their water. These cyanotoxin testing rules were developed in response to the cyanotoxin drinking water advisory in Salem during summer 2018.
  • We are fortunate to have high-quality drinking water sources and Oregon does not currently require us to test our water system for cyanotoxins.
  • If cyanotoxins are detected in our drinking water in the future, we will follow Oregon’s cyanotoxin rules for monitoring, testing, and public notification.
  • We tested the Bull Run source water for cyanotoxins in the summers of 2018 and 2019. All test results did not detect cyanotoxins in the water.

Risk of Harmful Algal Blooms

  • Even though the Bull Run Watershed is not currently at risk for harmful algal blooms, climate change may change the conditions of the watershed in the future.
  • A warming climate could increase the temperature of the region’s lakes, creating conditions that are more supportive of harmful algal blooms.
  • Additionally, climate change could increase the duration of hot, dry weather, which could increase the likelihood of wildfires. After a wildfire, more nutrients can run off the land into water bodies.
  • Currently, we do not have a way to remove algae or their potential toxins from our drinking water.
  • Our current treatment system could actually increase toxin levels. If toxin-producing cyanobacteria were present in the water, chlorine can break open the cyanobacteria cells and release toxins from inside the cells into the water.
  • Because there are currently no water treatment options to remove toxins from our water, there could be a public health risk if a harmful algal bloom occurred in the Bull Run Watershed.

How Filtration Reduces Risk

  • The new filtration facility will include ozone treatment that will destroy algal toxins and provide better protection against a range of future risks. 

Bull Run Treatment Projects

We are making two important improvements to our water supply from Bull Run to help keep our water safe and abundant for generations to come. Improved Corrosion Control Treatment will be in place in 2022 and will further adjust the chemistry of our water, reducing potential levels of lead at the tap. Filtration will be in operation in 2027 and will remove the microorganism Cryptosporidium and other potential contaminants from our water. Both projects are required under state and federal law.