Division of Drinking Water Harmful Algal Bloom & Cyanotoxin Response Plan

Harmful algal blooms (HABs) are rapid growths of algae that can produce cyanotoxins. These blooms are a possible source of contamination for surface water in Utah. The Division of Drinking Water recommends that Public Water Systems using surface water assess their vulnerability to potential HABs. Vulnerable water systems should be prepared with a Cyanotoxin Management Plan to respond to possible emergency situations including HABs and cyanotoxins. It is beneficial to the Water System, as well as the consumer, to have defined procedures in place to prevent harmful levels of cyanotoxins from reaching finished drinking water.

The Division of Drinking Water HAB response plan described below, provides Public Water Systems with guidelines, important information, and references needed to develop a Cyanotoxin Management Plan. It includes a protocol for monitoring, sampling, and analysis of source, raw, and finished water as necessary. The plan references Drinking Water Health Advisories from both the Environmental Protection Agency (EPA) and the World Health Organization (WHO) for three cyanobacterial toxins (Microcystins, Cylindrospermopsin, Anatoxin-a), and offers recommendations for public notification based on levels of cyanotoxins detected in the finished water.

What is a Harmful Algal Bloom?

An algal bloom is a sudden increase in the rate of growth or accumulation of phototrophic microorganisms (organisms that depend on light from the sun as its primary energy source). Phototrophic organisms include algae and cyanobacteria. In this document, the term algal blooms is inclusive of both algae and cyanobacteria. Not all algal blooms are harmful. They are naturally occurring in lakes, reservoirs, ponds and slow-flowing rivers. However, there is a potential for the blooms to become harmful due to the production of cyanotoxins by some species of phototrophs. The concern for drinking water quality is that these cyanotoxins can have a negative effect on human health when present in high enough concentrations.

What are cyanobacterial toxins?

Cyanobacterial toxins are referred to as cyanotoxins in this document. There are approximately 3,000 known species of cyanobacteria. Over fifty species have been identified as capable of producing toxins that pose serious public health risks and operational concerns, should they be found in drinking water sources. At high concentrations, some of these cyanotoxins are among the most powerful natural toxins of which no known antidotes exist (CDC n.d.). Other non-lethal cyanotoxins can trigger fevers, headaches, muscle and joint pain, diarrhea, vomiting or allergic skin reactions (WRF 2016).

This document references Health Advisory Levels (HALs) of three cyanotoxins currently being investigated by environmental agencies. The following cyanotoxin descriptions are referenced from Managing Cyanotoxins in Drinking Water: A Technical Guidance Manual for Drinking Water Professionals” (AWWA, WRF 2016) and Guidelines for Drinking Water Quality 4th ed. (WHO 2011). Further information can be found online, via the links provided in the reference section.

Microcystins

The most prevalent and heavily-researched group of cyanotoxins is the microcystins. These hepatotoxins occur most frequently in fresh waters. Unlike other cyanotoxins, the microcystins are commonly cell-bound, and are only released into the water in situations of cell rupture (ie: lysis). They are otherwise not water-soluble and do not break down on their own, even during boiling. With at least 160 reported variants of microcystin, successful treatment barriers capitalize on similarities between the various molecular structures of the variants.

Cylindrospermopsin

Most reports of the presence of cylindrospermopsin have come from the southern United States. This cyanobacterial metabolite has three known variants. In the typical pH range of natural waters, cylindrospermopsin is water-soluble. The structure of the molecules promotes hepatotoxicity, cytotoxicity, and genotoxicity. Of the three major functional groups of cylindrospermopsin, only one (uracil) is susceptible to oxidation.

Anatoxin-a

Anatoxin-a is a potent neurotoxin. Anatoxin-a has only one additional reported variant, homoanatoxin-a. Both variants are the smallest of the cyanotoxins. Anatoxin-a is typically found in its cationic form in natural waters, though changes in pH during drinking water treatment will impact the speed at which the compound is oxidized (Koskinen & Rapoport 1985). Anatoxin-a has two functional groups that are susceptible to oxidation, the amine and the unsaturated ketone.

Why Are Algal Blooms of Concern With Respect to Drinking Water?

Potential release of cyanotoxins in source water or through treatment process, can cause damage to the liver, nervous system, skin, and gastrointestinal system resulting in paralysis, organ damage, heart failure, and death.
Increased raw water turbidity, and shorter filter run times
Increased disinfection byproduct precursors
Increased operational costs
Odor, taste, and color problems in finished water
Customer loss of confidence in the quality of drinking water

Identifying a Bloom

Blooms can occur anywhere in the water column, sometimes appearing as green or blue-green flecks scattered in the water, scums that float on the surface, or mats that rest on the bottom. The Kansas Department of Health has developed a detailed procedure for visually identifying cyanobacteria in a bloom. The guide includes step-by-step instructions and pictures to aid in determining if a bloom is potentially harmful. Utah Water Watch has also drafted procedures for their volunteers on what to do “If You See a Bloom”. The public can be a useful resource in spotting potential blooms in source water. Water systems are encouraged to make the information in these documents available to their customers. Links to both documents:

Harmful Algae Bloom example photos (1 MB)
Regular non toxic algae example photos (2 MB)

Cyanobacteria and Associated Toxins

Cyanobacteria (Genera)	Total Microcystins	Cylindrospermopsin	Anatoxin-a	Saxitoxins
Anabaena	✓	✓	✓	✓
Anabaenopsis	✓
Aphanizomenon	✓	✓	✓	✓
Cylindrospermopsis		✓	✓	✓
Lyngbya		✓		✓
Microcystis	✓
Oscillatoria			✓	✓
Planktothrix	✓		✓	✓
Rhaphidiopsis		✓
Umezakia		✓

Cyanobacteria and Associated Toxins They May Produce