Being prepared for toxic algae season

As climate conditions continue to shift, Colorado has seen increasingly warm and nutrient-rich waters during the summer months — conditions that remain ideal for toxic algae to form in standing or slow-moving water. Toxic algae or harmful algae blooms (HABs) are made up of cyanobacteria, commonly known as blue-green algae. Although these organisms naturally occur in Colorado waters, they become a problem when they multiply rapidly, resulting in a dense cyanobacteria concentration or “bloom.” In drinking water sources, cyanobacteria blooms can cause the water to taste or smell bad. Taste and odor in drinking water is not regulated but creates customer concerns about water quality and safety. Most complaints that water utilities receive are about taste and odor, and these issues can last for prolonged periods. In addition to taste and odor problems, the blooms can become harmful and create a public health risk when they produce toxins. Removing toxins in a safe and cost-effective way can be a challenge for treatment facilities, and not all water providers are equipped to do so. 

Drinking water providers can contact the Water Quality Control Division at 303-692-3500 with questions about toxic algae. We can help water providers who experience taste and odor problems and toxins. This includes ideas about customer communication and steps that utilities can take to monitor and manage toxic algae and best treat their drinking water. If you detect microcystins above 0.3 μg/L and/or cylindrospermopsin above 0.7 μg/L (EPA’s cyanotoxin health advisory values), call the CDPHE 24-hour incident reporting hotline at 1-877-518-5608 so the division can provide you with immediate assistance.

We have resources to help drinking water providers and recreational water managers with toxic algae monitoring, response and public education and created a map to show recent toxic algae conditions for select waterbodies in the state. 

This 2019 AquaTalk article remains especially relevant today as cyanotoxins still pose a public health concern, even without being formally regulated. While EPA is continuing to evaluate the need for national regulation, the core takeaways from past events like Salem, Oregon’s microcystin advisory remain vital reminders for proactive communication, monitoring, and response. Whether you manage a public drinking water system or recreate on Colorado lakes and reservoirs, this piece offers timeless lessons for navigating toxic algae season safely.

Program Manager Message: An Open Letter to the Drinking Water Community - An Opportunity to Say THANK YOU!!!!

Hello everyone, 

In the May 2008 issue of Aqua Talk we ran an open letter of thanks to the drinking water community after the waterborne disease outbreak in Alamosa, Colorado. We have not had a waterborne disease outbreak at a public water system in Colorado in the 17 years since. We thought it would be a good time to rerun this article as a reminder of what happened and how the water utility community came together in response. We have had some disease outbreaks from drinking water, but they have happened in buildings or other situations that did not involve regulated systems. The Alamosa event was the first use of the Colorado Water and Wastewater Response Network (Co-WARN), which has been used many times since 2008 by utilities in need, and those needs have been met by other utilities. So, I say again - THANK YOU!

Article from May 2008: 

In March, the Water Quality Control Division in conjunction with numerous emergency response agencies and city of Alamosa officials were deeply involved in responding to a waterborne disease outbreak within the community. While a definitive identification of the cause has not yet been determined and investigative activities are ongoing, I want to take this opportunity and use this forum to tell everyone involved...Thank you!!

The city of Alamosa and the division could not have accomplished what they did without the assistance and dedication of all the agencies, groups and individuals involved with this response. The request for resources was placed to public water systems though our COWARN network, and the response was overwhelming and immediate. As new resource needs were identified, requests were made, and the resource materialized. Events and circumstances constantly evolved, and the response of the drinking water community was unwavering.

The boil/bottled water order was in place for 23 days and had an impact on the entire community of approximately 9,000 citizens. A staggering amount of work was accomplished within those 23 days including the following:

• An evaluation of the distribution system, including a review of potential cross­ connections.
• A multi-staged systematic disinfection and flushing of the storage tanks and entire 49 miles of distribution piping.
• Extensive monitoring for a number of water quality parameters throughout the distribution system including Salmonella, total coliform, Giardia, cryptosporidium, arsenic, lead and copper, and chlorine residuals.
• The Consumer Protection Division worked with restaurants and other businesses to keep many of them operating during the event.
• Bottled water and bulk water was distributed to residents.
• Communications personnel made substantial public notice efforts with the media to keep people informed.

The drinking water community should be proud of its response.

➽Ron Falco, P.E. Safe Drinking Water Program Manager