Don’t swim in the green water!

Don’t swim in the green water!

We can all agree that this has been an unusual year. This summer, the Lake Pend Oreille Waterkeeper (LPOW) office received calls about multiple shoreline development violations, people using soap in the lake, swimmers itch reports, and, most notably, green water. In early August, a resident on Comeback Bay notified us that the water was bright green from an algae bloom spreading around the shore of Sagle Slough. LPOW Executive Director Steve Holt drove out to the slough and then reported the algae bloom to the Idaho Department of Environmental Quality (DEQ). Several days later, DEQ and Panhandle Health District (PHD) posted a health advisory warning for the slough due to toxic algae in the water – one of the 25 warnings issued across the state.

This year there were three harmful algae blooms (or HABs) around our lake: Sagle Slough/Comeback Bay, Boyer Slough, and Chuck Slough. Typically, we rarely see algae blooms around our lake and seeing three in one summer was incredibly concerning

HAB in Boyer Slough, which is notorious for its annual algae blooms (August 2021)

Algae blooms are a natural part of surface water systems. And nutrients, such as phosphorus and nitrogen, are vital to healthy freshwater habitats. These nutrients are necessary for the growth of plants that provide food and habitat for aquatic organisms. Unfortunately, too many nutrients can lead to excessive plant growth, such as algae blooms. Excessive nutrients often come from wastewater treatment plant discharge, failing septic tanks, agriculture, fertilizer from farms and yards, and urban stormwater runoff.

A HAB, also known as blue-green algae or cyanobacteria, is the result of excessive algal growth which can be dangerous to human health and other organisms. HABs can produce toxins that can harm people, animals, aquatic ecosystems, and drinking water sources. If a body of water has an active HAB warning, people are advised to stay out of the water, keep their pets away from the HAB, and to rinse off with fresh water if they come into contact with it.

Bright green algae spreading along the shoreline in Comeback Bay – the first confirmed HAB in our watershed this year

Once a HAB is in a body of water, the water is unsafe to drink – even if boiled or treated. This is why it is so important to identify potential HABs as soon as possible and notify people who may visit the beach or drink the water. HABs vary in appearance, often looking like bright green water or pea soup, pollen, grass clippings, spilled paint, mats, green or blue-green foam, or dense surface scum. They are the exact opposite of what you want in the perfect swimming hole or in your drinking water source!

Once a HAB has been identified in a body of water, DEQ and PHD officials will continue to monitor the waterbody until the bloom has run its course, usually thanks to colder weather or rain. Unfortunately, DEQ and PHD do not have the time or resources to constantly monitor for HABs around our watershed and therefore rely on reports from the public, such as fishermen or shoreline property owners

Unfortunately there seems to be an ever increasing number of these incidents in our local area, throughout the state, and around the globe. This year we experienced 5 HABs in Bonner County and 25 total throughout the state. In north Idaho, we’ve had more than twice as many blooms as in a normal year. Brian Reese, DEQ’s Water Quality Standards Analyst for the state, said that algae blooms are happening more frequently, lasting longer, and becoming more toxic. This is due to increased nutrients in the water and increased temperatures. However, DEQ relies on citizens to report potential algae blooms so the numbers are not actually representative of how many algae blooms may occur.

Algae coating the rocks along Chuck Slough (August 2021)

This summer, we documented record high temperatures across Lake Pend Oreille and in the Pend Oreille River with our Water Quality Monitoring Program (WQMP). At City Beach, lifeguards reported water temperatures above 80°F for most of July. These temperatures were abnormally high for our area and almost certainly the result of human driven climate change. We have also seen a decline in the health of Lake Pend Oreille’s nearshore waters as indicated in DEQ’s 2015 TMDL review, which shows high levels of phosphorus. With the increased development of our shoreline and increased number of people coming to our area, we will likely see an increase in nutrients (such as phosphorus and nitrogen) in our lake due to stormwater pollution, decreased vegetative buffers along the shoreline, and increased wastewater treatment discharge. In other words, we’re concerned that the number of algae blooms will increase in the future and threaten the health of our lake. 

If you’re interested in learning more about this issue, please register for our Keeping up with the Waterkeeper Zoom event on November 4th. To report a potential HAB, take pictures and then call our pollution hotline at (208) 597-7188. Only professional water testing can confirm if HABs and toxins are present. And remember, when in doubt, stay out!

For up to date information about HABs in Idaho, check out DEQ’s website here: Also, check out the infographic about HABs below from the US Environmental Protection Agency – click on the image below to zoom in.

Update: If you’re interested in watching the Zoom recording, check it out on our YouTube Page here.